| 0 | 1,2-dichloroethane | 1,2-dichloroethane is a chlorinated hydrocarbon and an industrial solvent/chemical feedstock. In drinking water, it is an undesirable contaminant. | Primarily through industrial discharges, contaminated sites, leaking installations, contaminated soil or polluted groundwater. It is therefore not a naturally occurring component of water. | 1,2-dichloroethane is considered a health hazard and is associated with carcinogenic potential. It serves no purpose in drinking water and should ideally not be present. | Activated carbon: highly relevant, as it is an organic chlorinated substance.
Reverse osmosis membrane: can also help to reduce levels. | True | Under the German Drinking Water Ordinance, the limit is 0.0030 mg/l, i.e. 3 µg/l. |
| 1 | 1 | 2-dichloroethane is a chlorinated hydrocarbon and an industrial solvent/chemical feedstock. | Mainly due to industrial discharges, contaminated sites, leaking installations, contaminated soil or polluted groundwater. | 1,2-dichloroethane is considered a health hazard and is associated with carcinogenic potential.”,”Activated carbon: highly relevant, as it is an organic chlorinated substance.
Reverse osmosis membrane: may contribute further to reduction.”,True,”0.0030 mg/l, i.e. 3 µg/l. For individual plant protection products, the limit is usually 0.00010 mg/l, i.e. 0.1 µg/l.”
2,Acesulfame,Acesulfame | usually Acesulfame-K | is an artificial sweetener. It is used in food | drinks |
| 3 | Acrylamide
| Acrylamide is a chemical compound used primarily as a starting material for polyacrylamides. Polyacrylamides can be used in water treatment as flocculants or auxiliary agents. | industrial discharges, production and use of polymers. | is considered a health concern | Reverse osmosis membrane: this is the most effective domestic technology if the aim is to reduce a wide range of dissolved organic and inorganic substances. Activated carbon can adsorb many organic substances. However, it is less straightforward to guarantee its effectiveness against acrylamide, as acrylamide is highly water-soluble and relatively small. | True | 0.00010 mg/l, i.e. 0.1 µg/l. |
| 4 | Aluminium | “Aluminium is a metal that occurs naturally in soil and rock. In water treatment | aluminium salts can also be used as flocculants.” | “Through natural rock and soil layers | through water treatment with aluminium salts | or through certain materials. At unfavourable pH levels | aluminium can be dissolved more easily." |
| 5 | Ammonium | Ammonium is a nitrogen compound. It is produced during the decomposition of organic matter and can occur naturally in groundwater. In drinking water | it is primarily an indicator of potential contamination or treatment problems. | Through natural degradation processes in the soil, but also through sewage, slurry, agriculture, leaking septic tanks, biofilms or oxygen-depleted groundwater. | Ammonium is not as acutely critical as nitrite, but can be an indication of organic contamination or hygiene issues. It can also interfere with water treatment, for example during disinfection, and can be converted into nitrite and nitrate by bacteria.”,”Reverse osmosis membrane: can help reduce levels.
Activated carbon: not usually reliable for ammonium.”,True,0.50 mg/l." | | |
| 6 | Antimony
| Antimony is a semimetal. It occurs naturally in rocks, but is also used industrially, for example in alloys, plastics, flame retardants or certain materials. | Antimony can enter drinking water via natural rock and soil layers, but also through industry, contaminated sites, mining, wastewater or materials that come into contact with water. | Prolonged exposure to elevated levels can pose health risks, including to the gastrointestinal tract, liver and metabolism. | Reverse osmosis membrane: highly effective at reducing dissolved semimetals and ions.
Activated carbon: not usually the first choice for dissolved antimony. | True | currently set at 0.010 mg/l, i.e. 10 µg/l. From 12 January 2028, a stricter limit of 0.005 mg/l, i.e. 5 µg/l, will apply. |
| 7 | Arsenic | Arsenic is a naturally occurring semi-metal. In drinking water | it is an undesirable contaminant and has no benefit to the body. | It enters groundwater primarily through natural rock and soil layers. In addition, arsenic can enter the water via mining, industry, contaminated sites, wastewater or contaminated soil.”,”Arsenic poses a serious health risk. Long-term exposure can damage, amongst other things, the kidneys, liver, skin, nervous system and cardiovascular system. Certain arsenic compounds are also considered carcinogenic.”,Reverse osmosis membrane: highly effective at reducing dissolved arsenic. Activated carbon: standard activated carbon is usually not reliable enough for arsenic.,True,0.010 mg/l | i.e. 10 µg/l." | | |
| 8 | Benzo(a)pyrene | Benzo(a)pyrene is a polycyclic aromatic hydrocarbon – PAH for short. It is produced primarily during the incomplete combustion of organic material and is regarded as a particularly critical member of this group of substances. | Possible sources include contaminated sites, industry, exhaust fumes, soot, tar, contaminated soil or old tar-containing materials. In the context of drinking water, it may also be a concern due to certain old coatings or materials that come into contact with water.”, “Benzo(a)pyrene is classified as carcinogenic and serves no beneficial purpose in drinking water.”, “Activated carbon: highly relevant, as benzo(a)pyrene is an organic, hydrophobic substance and can be readily adsorbed.
Reverse osmosis membrane: can also contribute to its reduction. | True | 0.000010 mg/l, i.e. 0.01 µg/l. | | |
| 9 | Benzene | a highly volatile aromatic hydrocarbon. It originates primarily from fuels, industry, solvents, contaminated sites and exhaust fumes | Mostly through environmental or industrial releases, for example from leaking tanks, mineral oil/fuel contamination, contaminated sites or contaminated groundwater. | is considered highly hazardous to health, particularly due to its carcinogenic effects. | Activated carbon: highly relevant, as benzene is an organic, hydrophobic substance that can be readily adsorbed.
Reverse osmosis membrane: can further contribute to reduction, particularly when used in combination with activated carbon. | True | 0.001 mg/l, i.e. 1 µg/l |
| 10 | Bisphenol A | Bisphenol A, or BPA for short, is an industrial chemical that has been and continues to be used in plastics, epoxy resins and coatings, amongst other things. | Primarily via materials in contact with water, for example certain plastic components, internal coatings of pipes and containers, or epoxy resin coatings. The release from materials can be particularly high in hot water. | BPA serves no purpose in drinking water. It is considered harmful to health because, as an endocrine disruptor, it can have hormone-like effects. For this reason, the limit value in the Drinking Water Ordinance has been significantly tightened. | Activated carbon: highly effective, as BPA is an organic substance and can be readily adsorbed.
Reverse osmosis membrane: can also reduce BPA very effectively. | True | Under the German Drinking Water Ordinance, a limit of 0.0025 mg/l, i.e. 2.5 µg/l, has been in force since 12 January 2024. |
| 11 | Lead | Lead is a heavy metal | Mainly from old lead pipes, old domestic plumbing, solder joints or certain fittings. Stagnant water – that is, water that has been sitting in the pipes for a long time, for example overnight – is particularly critical.”,”Neurotoxic; can damage the nervous system, particularly in children. Lead can particularly affect the nervous system, blood formation and children’s development. Infants, children and pregnant women are particularly vulnerable.”, “Reverse osmosis membrane: highly effective at reducing dissolved lead.
Special activated carbon/block activated carbon: can reduce lead if tested or designed for this purpose. | True | The current limit is 0.010 mg/l, i.e. 10 µg/l. From 12 January 2028, a stricter limit of 0.005 mg/l, i.e. 5 µg/l, will apply. | | |
| 12. Boron | a naturally occurring semi-metal or trace element. In water | it is usually present as boric acid or borate. | It can naturally enter groundwater from rock and soil. Other sources include industry, wastewater, detergents and cleaning agents, fertilisers and the influence of seawater. | Excessive levels can pose health risks, particularly with long-term exposure. Boron is therefore subject to regulation. | Reverse osmosis membrane: generally suitable, but boron is challenging. Retention depends heavily on the pH value, the membrane and the quality of the system. | True | 1.0 mg/l. |
| 13 | Bromate | an undesirable oxidation or disinfection by-product | can be formed during certain treatment processes when raw water containing bromide is treated with ozone. In this process | bromate can be produced from bromide. Certain disinfectants may also contain bromate as a contaminant. | classified as a possible carcinogen | Reverse osmosis membrane: highly effective at reducing dissolved salts and ions such as bromate.
Activated carbon: only has limited effectiveness against bromate and is not a safe solution on its own. | True |
| 14 | Bromodichloromethane | “Bromodichloromethane is a trihalomethane | or THM for short. It is one of the undesirable disinfection by-products." | It is primarily formed when drinking water is treated with chlorine or chlorine-based disinfectants and organic substances as well as bromide are present in the water. | Bromodichloromethane has no beneficial use in drinking water. It is limited as a precautionary measure for health reasons, as THMs are undesirable if ingested over the long term and may be toxicologically relevant.”,”Activated carbon: highly effective, as THMs are organic compounds and can be readily adsorbed.
Reverse osmosis membrane: can also contribute to reduction. | True | There is no separate limit value for bromodichloromethane alone. It is included in the total for trihalomethanes. The limit is 0.050 mg/l, i.e. 50 µg/l, for the total of trichloromethane, bromodichloromethane, dibromochloromethane and tribromomethane. |
| 15 | Cadmium | Cadmium is a heavy metal and an undesirable contaminant in drinking water. | Possible sources include industry, mining, contaminated sites, fertilisers, contaminated soil, corrosion of materials or contamination from technical installations. | Cadmium can accumulate in the body and | in the long term | primarily affect the kidneys and bones. It is considered very harmful to health and should | if possible |
| 17 | Chlorate | Chlorate is a disinfection by-product. It can form when drinking water is disinfected with chlorine, chlorine dioxide or agents containing hypochlorite. It is not a desired constituent, but a by-product of treatment. | Primarily due to disinfectants and their storage or decomposition. Chlorate can form particularly with sodium hypochlorite if the agent is stored for too long, at too high a temperature, or incorrectly. | Excessive intake of chlorate can be harmful to health, particularly due to possible effects on the thyroid gland and blood formation. It is therefore subject to limits and monitored. | Reverse osmosis membrane: effective in reducing dissolved ions such as chlorate.
Activated carbon: not a reliable solution on its own for chlorate. | True | 0.070 mg/l, i.e. 70 µg/l. |
| 18 | Chlorite | Chlorite is a disinfection by-product. It is produced primarily when drinking water is disinfected with chlorine dioxide. In drinking water, chlorite is not a desired constituent, but a by-product subject to control. | Mainly through the use of chlorine dioxide in water treatment. Chlorite and chlorate can be produced as by-products in this process. | Chlorite can be harmful to health at high concentrations and is primarily associated with adverse effects on the blood, the thyroid and oxidative stress. It is therefore subject to limits and monitoring.”, “Reverse osmosis membrane: effective in reducing dissolved ions such as chlorite.
Activated carbon: may help reduce concentrations depending on the material and contact time, but is not always a safe solution on its own. | True | 0.20 mg/l, i.e. 200 µg/l. | |
| 19 | Chromium | a metal or trace element. In water, it is particularly important to distinguish between chromium(III) and chromium(VI). Chromium(III) is significantly less harmful, whilst chromium(VI) poses a health risk and is classified as carcinogenic. | It can, of course, enter groundwater from rock and soil. Other sources include industry, contaminated sites, metal processing, tanneries, corrosion protection, paints/pigments and contaminated soil. | Chromium(VI) in particular is of concern because it is significantly more toxic than chromium(III). It is classified as carcinogenic | Reverse osmosis membranes, activated carbon: not the first choice for dissolved chromium; effectiveness depends heavily on water chemistry and filter material. | True | 0.025 mg/l, i.e. 25 µg/l. From 12 January 2030, the limit will be reduced to 0.005 mg/l, i.e. 5 µg/l. |
| 20 | Coliform bacteria | Coliform bacteria are a group of bacteria that can be found in the environment, in soil, on plants, and also in the intestines of humans and animals. In drinking water, they are an important hygiene and indicator parameter. | Possible causes include leaky pipes, biofilm, stagnation, surface water, well contamination, pipework, sewage or faecal contamination, and hygiene issues in the water supply. | The presence of coliform bacteria does not automatically mean that pathogens are present. However, their detection indicates that contamination or a hygiene vulnerability is possible. The cause must therefore be investigated. | Activated carbon blocks with very fine pores retain bacteria. Reverse osmosis membrane: generally retains bacteria | True | Under the German Drinking Water Ordinance |
| 21 | Cyanide | “is a chemical compound consisting of carbon and nitrogen. Free cyanide is particularly problematic because it can be highly toxic.” | “Mostly due to industrial discharges | electroplating | metal processing | mining | contaminated sites |
| 22 | Diatrizoate | Diatrizoate, also known as amidotrizoic acid, is an iodinated X-ray contrast agent. It is used in medical imaging procedures to make structures within the body more visible. | After the examination, most of the diatrizoate is excreted. It enters rivers, bank filtrate, groundwater and, to some extent, drinking water via wastewater and sewage treatment works. Iodinated X-ray contrast agents are described by the Federal Environment Agency as mobile and persistent trace substances. | Diatrizoate serves no purpose in drinking water. It is particularly problematic because it is highly water-soluble, mobile and persistent. At typical trace concentrations, it is not so much considered an acute health risk as an indication of wastewater influence and medical trace substances that are difficult to remove. | Reverse osmosis membrane: highly relevant, as diatrizoate is present in a dissolved and mobile state. Activated carbon: may be effective depending on the type of carbon, contact time and water chemistry, but is not always reliable with highly polar X-ray contrast media. | False | There is no specific limit value for diatrizoate in the German Drinking Water Ordinance. From a technical perspective, a health-based guideline value of 1.0 µg/l is often cited for iodinated X-ray contrast agents or diatrizoate. |
| 23 | Diazepam | Diazepam is an active pharmaceutical ingredient belonging to the benzodiazepine group. It is used, amongst other things, as a sedative, anxiolytic, muscle relaxant and antispasmodic. In drinking water, it is an undesirable pharmaceutical trace substance. | Primarily via human excreta, wastewater and sewage treatment plants. According to the Federal Environment Agency, pharmaceutical residues can be discharged into water bodies via sewage treatment plants and occur there as trace substances. | Diazepam serves no purpose in drinking water. As a biologically active substance, it is undesirable in the water cycle. Although concentrations are generally far below therapeutic doses, pharmaceutical residues are nevertheless relevant from a precautionary and environmental perspective. | Activated carbon: effective for many organic pharmaceutical residues.
Reverse osmosis membrane: broadly effective against many dissolved trace substances. | False | There is no specific limit value for diazepam in the German Drinking Water Ordinance. It is not included among the standard mandatory chemical parameters listed in Annex 2 |
| 24 | Dibromochloromethane | Dibromochloromethane is a trihalomethane, or THM for short. It is a disinfection by-product and is not produced intentionally, but arises during water disinfection. | It can form when water is treated with chlorine or chlorine-based disinfectants and organic substances as well as bromide are present in the water at the same time. | Dibromochloromethane serves no useful purpose in drinking water. It is one of the undesirable by-products of disinfection and is subject to precautionary limits to protect public health. Of particular relevance is long-term exposure via drinking water. | Activated carbon: highly relevant, as THMs are organic compounds and can be readily adsorbed.
Reverse osmosis membrane: can also contribute to reduction.”,True,”There is no separate individual limit value for dibromochloromethane alone. It is included in the total for trihalomethanes. The limit value is 0.050 mg/l, i.e. 50 µg/l, for the total of chloroform, bromodichloromethane, dibromochloromethane and bromoform.”
25,Diclofenac,Diclofenac is a commonly used active pharmaceutical ingredient for treating pain and inflammation. In drinking water, it is an undesirable trace substance. “Primarily through human use. Residues enter rivers, lakes, groundwater and, in some cases, drinking water via urine, wastewater and sewage treatment plants. The Federal Environment Agency explicitly lists diclofenac as an active pharmaceutical ingredient that has been detected in water bodies and also in drinking water. | For humans, the quantities found in drinking water are usually well below therapeutically effective doses. From an environmental perspective, however, diclofenac is highly relevant because it is biologically active and can harm aquatic organisms. The UBA describes diclofenac as one of the problematic pharmaceutical substances in water bodies.”,”Activated carbon: highly effective against many organic pharmaceutical residues.
Reverse osmosis membrane: broadly effective against many dissolved trace substances. | |
| 26 | E. coli | Escherichia coli, or E. coli for short, is a bacterium found in the intestines of humans and animals. In drinking water, E. coli is a very important faecal indicator.”, “Through sewage, faeces, slurry, leaking pipes, heavy rainfall, surface water, well contamination or hygiene issues in the water supply.”,E. coli indicates that faecal contamination is possible. This means that other pathogens could also be present in the water. Any detection must therefore always be taken seriously." | Activated carbon blocks with very fine pores retain bacteria. Reverse osmosis membrane: generally retains bacteria. True | the German Drinking Water Ordinance specifies a limit of 0/100 ml for E. coli. For water in sealed containers | the limit is 0/250 ml. E. coli must therefore not be detectable in drinking water. | | |
| 27 | Iron | Iron is a naturally occurring metal and an important trace element. In drinking water, it is not usually an acute health concern, but can cause technical and visual problems.”,”Mainly due to iron-bearing rock and soil layers, groundwater, old pipes, corrosion or deposits in the plumbing system.”,”Elevated iron levels can lead to a rust-brown colour, a metallic taste, cloudiness, deposits and discolouration on taps, laundry or sanitary surfaces. Furthermore, iron can promote the formation of biofilms and cause technical problems in filters, pipes or systems.”,Reverse osmosis membrane: can reduce iron | but should not be exposed directly to water with a high iron content | as this can cause the membrane to become clogged. | | | |
| Activated carbon: not the first choice" | True | 0.200 mg/l, i.e. 0.2 mg/l. | | | | | |
| 28 | Epichlorohydrin | Epichlorohydrin is a chemical compound used in the manufacture of certain synthetic resins, epoxy resins and polymers. In drinking water, it is an undesirable technical residue. | Primarily via materials or treatment agents that come into contact with drinking water. Of particular relevance are possible residual amounts from certain resins, coatings or polymers.”,Epichlorohydrin is considered a health hazard and is subject to very strict limits.,”Activated carbon: relevant for many organic compounds; can help reduce their levels.
Reverse osmosis membrane: can also help reduce dissolved organic substances. | True | 0.00010 mg/l, i.e. 0.1 µg/l. | | |
| 29 | Estradiol | Estradiol – more specifically, usually 17β-estradiol – is a natural oestrogen hormone. It occurs in the human and animal body and is biologically very potent. | Primarily via excreta, wastewater, sewage treatment plants, livestock farming, slurry, surface water and bank filtrate. Sewage treatment plants cannot always completely remove endocrine-active trace substances. | Oestradiol has no beneficial effect in drinking water. It is an endocrine-active substance, i.e. it has hormonal activity. Even very low concentrations can be significant in the environment, particularly for aquatic organisms and their reproduction. | Activated carbon: highly effective for many organic endocrine-active substances.
Reverse osmosis membrane: broadly effective against many dissolved trace substances. | False | There is currently no standard individual limit value for oestradiol in the German Drinking Water Ordinance, as there is for nitrate or lead. However, the EU has placed beta-oestradiol on a watch list for emerging substances that are to be monitored more closely in the drinking water supply. |
| 30 | Ethinyl oestradiol | Ethinyl oestradiol, also known as 17α-ethinyl oestradiol or EE2, is a synthetic oestrogen. It is primarily used in hormonal contraceptives. In drinking water, it is an undesirable hormone-active trace substance. | Mainly via human excreta, wastewater and sewage treatment plants. From there, it can enter surface waters, bank filtrate, groundwater and, in trace amounts, drinking water as well. | Ethinyl oestradiol is biologically active even at very low concentrations. It is particularly relevant for aquatic organisms because endocrine-disrupting substances can affect reproduction and development. The UBA lists 17α-ethinyl oestradiol, alongside oestradiol and oestrone, as a hormone-active substance on the EU watchlist for water bodies. | Activated carbon: highly effective for many hormone-active organic trace substances.
Reverse osmosis membrane: broadly effective against many dissolved trace substances. | False | There is no specific limit value for ethinyl oestradiol in the German Drinking Water Ordinance. It is not one of the standard parameters such as nitrate, lead or PFAS. |
| 31 | Fluoroquinolones | Fluoroquinolones are a group of antibiotics, such as ciprofloxacin, levofloxacin, ofloxacin and norfloxacin. In drinking water, they are undesirable pharmaceutical trace substances. | They enter the environment primarily via human and veterinary use, excreta, wastewater, sewage treatment plants, slurry, agriculture and surface water. After use, antibiotics can enter the environment, where they can harm organisms and promote resistance. | Fluoroquinolones serve no purpose in drinking water. They are biologically active antibiotics and are therefore undesirable in the water cycle. This issue is particularly relevant due to the potential for antibiotic resistance and effects on microorganisms in the environment. | Activated carbon: relevant for many organic pharmaceutical residues.
Reverse osmosis membrane: broadly effective against many dissolved trace substances. | False | There is no specific limit value for fluoroquinolones in the German Drinking Water Ordinance. They are not included among the standard mandatory chemical parameters listed in Annex 2 |
| 32 | Fluoride | Fluoride is a naturally occurring mineral or | more specifically | a salt of hydrofluoric acid. It may be naturally present in water in small quantities. | This is primarily due to rock and soil layers from which fluoride can leach into groundwater. In some regions, the natural fluoride content is higher. Industrial inputs are also possible, but are rarely a significant factor. | Fluoride must be assessed on a dose-dependent basis. In small quantities, it can help prevent tooth decay. However, too much fluoride can be problematic, particularly in children, as it can lead to dental fluorosis. This causes discolouration or changes to the tooth enamel. | Reverse osmosis membrane: highly effective at reducing fluoride.
Activated carbon: not usually reliable enough for fluoride. |
| 33 | Gadolinium | Gadolinium is a metal from the rare-earth group. Of particular relevance in water is anthropogenic gadolinium from medical MRI contrast agents. | After an MRI scan, gadolinium-containing contrast agents are largely excreted. They enter rivers, bank filtrate, groundwater and, to some extent, drinking water via wastewater and sewage treatment plants. Studies have detected anthropogenic gadolinium from MRI contrast agents in surface waters and also in tap water. | Gadolinium has no beneficial use in drinking water. Medical contrast agents are very stable, water-soluble and persistent. The traces found are generally not considered to pose an acute health risk, but they are a clear indication of the influence of wastewater and of medical trace substances that are difficult to remove. | Reverse osmosis membrane: relevant, as gadolinium-containing contrast agents are present in a dissolved and mobile state. Activated carbon: has only limited or unreliable effectiveness for many gadolinium-containing contrast agents, as they are highly polar and stable. | False | There is no specific limit value for gadolinium in the German Drinking Water Ordinance. It is not a standard parameter like nitrate, lead or PFAS. |
| 34 | Glyphosate | Glyphosate is a herbicide, i.e. a weedkiller. It is used in agriculture and, to some extent, in non-agricultural applications. In drinking water, glyphosate is an undesirable active ingredient in plant protection products. | It enters the water cycle primarily through agricultural use, run-off from land, soil input, surface water, seepage water and contaminated groundwater. The main degradation product is AMPA. | Glyphosate serves no purpose in drinking water. The main issue is that it indicates the presence of plant protection products and can occur as a trace substance in the water cycle. The assessment of glyphosate has been the subject of controversy for years; consequently, the strict precautionary limit for plant protection products applies to drinking water. | Reverse osmosis membrane: effective in reducing many dissolved pesticides and trace substances.
Activated carbon: can reduce glyphosate depending on the type of activated carbon, contact time and water chemistry, but this cannot always be reliably predicted. | True | For glyphosate as an individual active ingredient in plant protection products, the drinking water limit of 0.00010 mg/l, i.e. 0.1 µg/l, applies. For the total of plant protection products, the limit is 0.5 µg/l. |
| 35 | HFPO-DA | HFPO-DA stands for hexafluoropropylene oxide dimer acid. The substance is also known as GenX and belongs to the PFAS group of substances. It has been used | amongst other things | as a substitute for older PFAS such as PFOA. | Primarily from industry, fluorochemicals, production processes containing PFAS, wastewater, sewage treatment works, contaminated soil and groundwater. HFPO-DA is highly persistent and mobile. | HFPO-DA has no beneficial use in drinking water. It is problematic because it is one of the long-lived PFAS and can spread throughout the water cycle. Furthermore, it is considered to be of toxicological significance and is therefore increasingly the focus of water analysis.”,”Reverse osmosis membrane: highly relevant, as HFPO-DA is present in a dissolved and mobile state. Activated carbon: may be effective depending on the type of carbon, contact time and water chemistry; however, it is less reliable for mobile/short-chain or ether-based PFAS than for long-chain PFAS. | False |
| 37 | Ibuprofen | Ibuprofen is a commonly used active pharmaceutical ingredient from the group of painkillers and anti-inflammatories. In drinking water | it is an undesirable trace substance. | Primarily via human consumption: After ingestion, residues are excreted in the urine and enter the wastewater. Wastewater treatment plants cannot always remove pharmaceutical residues completely, meaning they can enter rivers, lakes, groundwater and, in isolated cases, drinking water.”,”Ibuprofen has no benefit in drinking water. For humans, detected concentrations in drinking water are usually far below therapeutically effective doses. From an environmental perspective, however, pharmaceutical substances are still relevant because they are biologically active and can affect aquatic organisms.”, “Activated carbon: effective against many organic pharmaceutical residues.
Reverse osmosis membrane: highly effective against many dissolved trace substances. | | There is no specific limit value for ibuprofen in the German Drinking Water Ordinance. Pharmaceutical residues are usually classified as trace substances, not as standard limit value parameters | |
| 38 | Intestinal enterococci | Intestinal enterococci are bacteria found in the intestines of humans and animals. In drinking water, they act as a faecal indicator, i.e. an indication of possible contamination by faeces. | “Through sewage | leaking pipes | surface water | slurry | livestock farming |
| 39 | Iohexol | Iohexol is an iodinated X-ray contrast agent. It is used in CT and X-ray examinations to make blood vessels, organs or tissues more visible. In drinking water, it is an undesirable medical trace substance. | After the examination, iohexol is largely excreted by the body. It enters rivers, bank filtrate, groundwater and, to some extent, drinking water via wastewater and sewage treatment plants. | Iohexol serves no purpose in drinking water. It is particularly relevant because it is highly water-soluble, mobile and difficult to biodegrade. In the short term, the main concern is usually not a direct health risk from trace concentrations, but rather the indication of wastewater influence and medical residues that are difficult to remove. | Activated carbon: may be effective depending on the type of carbon, contact time and water chemistry, but is not always reliable for highly polar X-ray contrast agents. Reverse osmosis membrane: highly relevant, as iohexol is present in a dissolved and mobile state. | False | There is no specific limit value for iohexol in the German Drinking Water Ordinance. It is classified as a trace substance or X-ray contrast agent, not as a standard mandatory parameter such as nitrate, lead or PFAS. |
| 40 | Iomeprol | Iomeprol is an iodinated X-ray contrast agent. It is used in CT and X-ray examinations to make organs, blood vessels or tissues more visible. | After the examination, most of the iomeprol is excreted by the body. It enters rivers, bank filtrate, groundwater and, to some extent, drinking water via wastewater and sewage treatment plants. The Federal Environment Agency explicitly names Iomeprol as a known iodinated X-ray contrast agent and describes this group of substances as highly water-soluble, stable and frequently detectable in surface waters as well as in drinking water. | Iomeprol serves no purpose in drinking water. It is particularly problematic because it is highly water-soluble, polar, stable and mobile. In acute cases, the focus is usually not on direct toxicity, but on persistence, the impact on wastewater and possible transformation products. | Reverse osmosis membrane: highly relevant, as iomeprol is present in a dissolved and mobile state. Activated carbon: may be effective, but is not always reliable with highly polar X-ray contrast media. | False | There is no specific limit value for iomeprol in the German Drinking Water Ordinance. Technically, guideline or target values in the range of 0.1 to 1 µg/l are frequently cited for X-ray contrast media. |
| 41 | Iopamidol | Iopamidol is an iodinated X-ray contrast agent. It is used in CT and X-ray examinations to make blood vessels, organs or tissues more visible. | After the examination, most of the iopamidol is excreted. It enters rivers, bank filtrate, groundwater and, to some extent, drinking water via wastewater and sewage treatment plants. The Federal Environment Agency classifies iopamidol, as representative of iodinated X-ray contrast media, as a relevant trace substance. | Iopamidol serves no purpose in drinking water. It is highly water-soluble, mobile and persistent. It is considered less of an acute toxic problem in drinking water and more, above all, an indication of wastewater influence and medical trace substances that are difficult to remove. | Activated carbon: may be effective, but is not always reliable for iodinated contrast agents; Studies are specifically investigating powdered activated carbon for iopamidol, amongst other things. Reverse osmosis membrane: highly relevant, as iopamidol is present in a dissolved and mobile state. | False | There is no specific limit value for iopamidol in the German Drinking Water Ordinance. For X-ray contrast media |
| 42 | Potassium | Potassium is a naturally occurring mineral and an important electrolyte for the body. Among other things, it plays a role in nerve and muscle function and fluid balance. | Primarily through rock, soil and minerals. In addition, potassium can enter groundwater via agriculture, fertilisers, wastewater, road-gritting salt inputs or geological features. | Potassium is not harmful in itself, but is a vital mineral. In drinking water, it is usually regarded more as a parameter for mineralisation and as an indicator. Elevated levels may indicate geological features, agricultural inputs or, in isolated cases, contamination. The NLWKN points out that a potassium content higher than that of sodium may indicate specific geochemical conditions or faecal contamination. | Reverse osmosis membrane: significantly reduces potassium. Activated carbon is not suitable for targeted potassium reduction. | False | There is no limit value for potassium in the German Drinking Water Ordinance. Limit values used to exist, but these no longer apply. |
| 43 | Colony count at 20°C | “The colony count at 20 °C indicates how many viable microorganisms can grow in the water at a low ambient temperature. It does not refer to a specific pathogen | but is a general indicator of hygiene and system performance. Important: The current German Drinking Water Ordinance usually specifies the colony count at 22 °C. Some laboratory reports or older/alternative methods also specify 20 °C. In substance | this is a very similar indicative value for environmental bacteria and microbiological stability.” | ”Due to natural water flora | biofilm | stagnation |
| 44 | Colony count at 36 °C | The colony count at 36 °C indicates how many viable microorganisms can grow in water at a temperature close to body temperature. It does not represent a single pathogen, but rather a microbiological hygiene and indicator parameter. | Possible causes include biofilm, stagnation, warm sections of pipework, storage tanks, fittings, filters, deposits or treatment problems. | An elevated colony count does not automatically mean that pathogens are present. However, it may indicate hygiene issues, biofilm growth, stagnation or unfavourable temperatures. Sudden or significant changes compared with previous readings are particularly relevant. | Activated carbon blocks with very fine pores retain bacteria. Reverse osmosis membrane: generally retains bacteria | True | In the Drinking Water Ordinance |
| 45 | Copper | Copper is a metal and | at the same time | an important trace element. However | it is undesirable in drinking water at excessive concentrations. | Mainly due to copper pipes, taps, boilers, domestic plumbing and corrosion. Stagnant water – that is, water that has been sitting in the pipes for a long time – is particularly relevant.”, “Too much copper can be problematic, especially for sensitive individuals, particularly infants or people with certain liver conditions. It can also affect the taste and colour of the water. | Reverse osmosis membrane: highly effective at reducing dissolved copper.
Specialised activated carbon / adsorption media: can reduce copper if they are designed and tested for this purpose. |
| 46 | Legionella | Legionella are bacteria that can occur naturally in water. They become a particular problem when they multiply in hot-water systems, storage tanks, pipes, showers, taps or biofilms. | They can be introduced via the raw water or the plumbing system and thrive particularly well at lukewarm temperatures, in stagnant water, biofilms, deposits and poorly maintained hot-water systems. | Legionella bacteria are particularly dangerous when inhaled via aerosols, for example whilst showering. In such cases, they can cause Legionnaires’ disease – a severe form of pneumonia – or the milder Pontiac fever. Drinking is not usually the main route of infection.”,Activated carbon blocks with very fine pores retain Legionella. Reverse osmosis membrane: generally retains bacteria,True,Under the Drinking Water Ordinance | a technical action level of 100 CFU/100 ml applies to Legionella spec. If this level is reached | measures such as reporting the incident | investigating the cause and taking remedial action are required." |
| 47 | Macrolides | Macrolides are a group of antibiotics, such as clarithromycin, azithromycin or erythromycin. In drinking water, they are undesirable pharmaceutical trace substances. | “Primarily via human excreta | wastewater and sewage treatment plants. Sewage treatment plants cannot always completely remove pharmaceutical residues | meaning that residues can enter water bodies | groundwater and | in isolated cases |
| 48 | Manganese | Manganese is a naturally occurring metal and | in very small quantities | an important trace element. In drinking water | however | it is primarily an indicator parameter and is of technical relevance. | Mainly due to manganese-containing rock and soil layers, oxygen-depleted groundwater, well water or deposits in pipes and systems. |
| 49 | Metoprolol | Metoprolol is an active pharmaceutical ingredient belonging to the group of beta-blockers. It is used, amongst other things, to treat high blood pressure, cardiac arrhythmias and other cardiovascular diseases. In drinking water, metoprolol is an undesirable pharmaceutical trace substance.”, “Primarily via human excreta, wastewater and sewage treatment plants. According to the Federal Environment Agency, pharmaceutical residues can enter water bodies via sewage treatment plants and occur there as trace substances.”,Metoprolol serves no purpose in drinking water. The concentrations typically found are far below therapeutic doses; nevertheless | the substance is undesirable because it is biologically active and can remain in the water cycle." | Activated carbon: effective against many organic pharmaceutical residues.
Reverse osmosis membrane: broadly effective against many dissolved trace substances. | False | There is no specific limit value for metoprolol in the German Drinking Water Ordinance. It is regarded as an organic trace substance, not as a regular mandatory parameter. | |
| 50 | Nickel | Nickel is a metal and is found in many alloys. In drinking water, it is an undesirable substance that can originate primarily from materials used in domestic plumbing. | Primarily from taps, nickel-plated components, stainless steel parts, fittings or other metallic materials. Stagnant water – that is, water that has been standing in pipes or taps for a long time – is particularly relevant.”,Nickel can trigger or exacerbate allergic reactions in sensitive individuals. People with a nickel allergy in particular should avoid elevated nickel levels in drinking water.,Reverse osmosis membrane: highly effective at reducing dissolved nickel. | | | | |
| Specialised adsorption media / activated carbon filters: can reduce nickel if they have been tested and designed for this purpose." | True | 0.020 mg/l, i.e. 20 µg/l. | | | | | |
| 51 | Nitrate | Nitrate is a nitrogen compound and occurs naturally in the soil. It is also an important plant nutrient. Levels: 0–5 mg/L
low, 5–10 mg/L moderate, 10–25 mg/L elevated, 25–50 mg/L significantly elevated but below the limit, above 50 mg/L above the limit / non-compliant
| Mainly from agriculture, fertiliser application, slurry, intensive livestock farming, wastewater, and leaking sewage treatment tanks or septic tanks. Nitrate can easily leach into groundwater. | Nitrate itself is not the main problem, but it can be converted into nitrite in the body or in water. Nitrite can be particularly harmful to infants, as it can impair oxygen transport in the blood. Furthermore, under certain conditions, nitrosamines – which are harmful to health – can form from nitrite. | Reverse osmosis membrane, activated carbon: not usually reliable for nitrate | True | at 50 mg/l. |
| 52 | Nitrate/50 + Nitrite/3 | This is not a substance in its own right, but a calculation rule from the Drinking Water Ordinance. It assesses the combined load of nitrate and nitrite. The formula is:
Nitrate in mg/l ÷ 50 + Nitrite in mg/l ÷ 3 ≤ 1
The result must therefore not exceed 1. | Nitrate and nitrite originate predominantly from the nitrogen cycle. Nitrate enters groundwater primarily through agriculture, fertilisation and slurry. Nitrite is usually formed as an intermediate product during microbial conversion processes and may indicate biological activity, stagnation or problems in pipework and treatment systems. In addition to the individual limit values, the combination is also important: Nitrate/50 + Nitrite/3 must not exceed 1. | Nitrate and nitrite are chemically related. Under certain conditions, nitrate can be converted into nitrite. Nitrite is particularly critical because it can impair oxygen transport in the blood, especially in infants.
Example:
If water contains 40 mg/l of nitrate and 0.3 mg/l of nitrite:
40 ÷ 50 = 0.8
0.3 ÷ 3 = 0.1
Result: 0.9 | Reverse osmosis membrane: highly effective at reducing nitrate and nitrite. Activated carbon: not reliable for removing nitrate or nitrite. | True | Nitrate: 50 mg/l
Nitrite: 0.50 mg/l
In addition, a stricter limit of 0.10 mg/l applies to nitrite at the waterworks outlet. |
| 53 | Nitrite | Nitrite is a nitrogen compound and an intermediate product between ammonium, nitrate and nitrogen. | Nitrite can be produced by the microbiological conversion of nitrate or ammonium. Sources may include agriculture, sewage, biofilms, stagnation, technical problems in water treatment or faulty disinfection. | Nitrite can impair oxygen transport in the blood. Infants are particularly vulnerable, as they are at higher risk of so-called ‘blue baby syndrome’. Furthermore, under certain conditions, nitrites can form nitrosamines, which are harmful to health. | Reverse osmosis membrane: highly effective at reducing nitrite.
Activated carbon: not usually reliable for removing nitrite. | True | at 0.50 mg/l. A stricter limit of 0.10 mg/l also applies at the waterworks outlet. |
| 54 | Orthophosphate (o-PO₄) | Orthophosphate is a dissolved form of phosphate. Phosphates are salts of phosphoric acid and occur naturally in soils, rocks, plants and biological processes. | Orthophosphate can enter groundwater naturally from soil, rock and organic material. Other sources include agriculture, fertilisers, wastewater, sewage treatment works, or deliberate addition during drinking water treatment or in domestic plumbing systems for corrosion protection. | Orthophosphate is not primarily a toxic pollutant. However, elevated levels may indicate the influence of wastewater, agriculture or surface water. Furthermore, as a nutrient, phosphate can promote microbiological growth if unfavourable hygienic conditions are present at the same time. | Reverse osmosis membrane: effective for reducing dissolved phosphates. Activated carbon: not normally reliable for orthophosphate. | | The German Drinking Water Ordinance does not currently specify a separate limit value for orthophosphate as a drinking water parameter. The Groundwater Ordinance specifies a threshold value of 0.5 mg/l for orthophosphate. |
| 55 | Paracetamol | Paracetamol is a commonly used active pharmaceutical ingredient for the treatment of pain and fever. In drinking water | it is an undesirable trace substance. | Primarily via human use: residues are excreted and enter water bodies via wastewater and sewage treatment plants. According to the Federal Environment Agency, pharmaceutical residues are detected in water bodies, soil, groundwater and sometimes also in drinking water. | Paracetamol has no benefit in drinking water. The traces that may be present in drinking water are normally far below therapeutic doses. Nevertheless, pharmaceutical residues are undesirable because they are biologically active substances and can harm the environment. | Activated carbon: effective for many organic pharmaceutical residues.
Reverse osmosis membrane: broadly effective against many dissolved trace substances. | False |
| 56 | Perfluorobutanoic acid (PFBA) | PFBA is a single compound from the PFAS group of substances. It belongs to the short-chain perfluorinated carboxylic acids and is a so-called ‘forever chemical’ because it is very persistent in the environment. | Primarily through industry, PFAS-containing products, coatings, impregnations, sewage treatment plants, landfill sites, contaminated soil and groundwater. PFBA is particularly mobile and can easily spread throughout the water cycle. | PFBA has no beneficial use in drinking water. It is problematic because it is highly persistent and highly mobile. Although short-chain PFAS such as PFBA generally accumulate to a lesser extent in the body than long-chain PFAS, they are often more difficult to remove from water. | Reverse osmosis membrane: highly effective, particularly for mobile short-chain PFAS. Activated carbon: often less reliable for short-chain PFAS such as PFBA than for long-chain PFAS such as PFOS or PFOA. | True | There is no separate individual limit value for PFBA in the Drinking Water Ordinance. However, PFBA is a component of the ‘PFAS-20’ total. A limit value of 0.1 µg/l has applied to the total of the 20 listed PFAS since 12 January 2026. |
| 57 | Perfluorobutanesulfonic acid (PFBS) | PFBS is a single compound from the PFAS group of substances. It belongs to the short-chain perfluorinated sulfonic acids and is also considered a persistent ‘forever chemical’. | Mainly from industry, products containing PFAS, impregnations, coatings, sewage treatment plants, landfill sites, contaminated soil and groundwater. PFBS has sometimes been used as a substitute for older long-chain PFAS such as PFOS. | PFBS has no beneficial use in drinking water. It is highly persistent and mobile. Short-chain PFAS such as PFBS generally accumulate to a lesser extent in the body than long-chain PFAS, but are often more difficult to remove using activated carbon. | Reverse osmosis membrane: highly effective, particularly for mobile short-chain PFAS. Activated carbon: often less reliable for short-chain PFAS such as PFBS than for long-chain PFAS such as PFOS or PFOA. | True | There is no separate individual limit value for PFBS. However, PFBS is a component of the PFAS-20 total. A limit of 0.1 µg/l has applied to the sum of the 20 listed PFAS since 12 January 2026. |
| 58 | Perfluorodecanoic acid (PFDA) | PFDA is a single compound from the PFAS group of substances. It belongs to the group of long-chain perfluorinated carboxylic acids and is classified as a persistent ‘forever chemical’." | Mainly through industry, PFAS-containing products, coatings, impregnations, landfill sites, sewage treatment plants, contaminated soil and groundwater. Like other PFAS, PFDA can persist in the environment for a long time. | PFDA has no beneficial use in drinking water. It is problematic because it is highly persistent and, as a long-chain PFAS, is more likely to bioaccumulate in the environment and organisms than many short-chain PFAS. | Reverse osmosis membrane: highly effective and broadly active against PFAS.
Activated carbon: generally much more effective for long-chain PFAS such as PFDA than for short-chain PFAS. | True | There is no separate individual limit value for PFDA. However, PFDA is a component of the total PFAS-20. A limit of 0.1 µg/l has applied to the sum of the 20 listed PFAS since 12 January 2026. From 2028, the PFAS-4 limit will also apply, although PFDA is not included in PFAS-4 |
| 59 | Perfluorodecanesulfonic acid (PFDS) | PFDS is an individual compound from the PFAS group of substances. It belongs to the long-chain perfluorinated sulfonic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily through industry, PFAS-containing products, coatings, impregnations, fire-fighting foams, landfill sites, sewage treatment works, contaminated soil and groundwater. | PFDS has no beneficial use in drinking water. It is highly persistent and | as a long-chain PFAS | is more likely to bioaccumulate in the environment and organisms than many short-chain PFAS. It is therefore undesirable in drinking water. | Reverse osmosis membrane: highly effective and broadly active against PFAS.
Activated carbon: generally significantly more effective for long-chain PFAS such as PFDS than for short-chain PFAS.”,True,”There is no separate individual limit value for PFDS. However, PFDS is a component of the PFAS-20 total. A limit of 0.1 µg/l has applied to the total of the 20 listed PFAS since 12 January 2026. PFDS does not belong to the PFAS-4 group. |
| 60 | Perfluorododecanoic acid
(PFDoDA) | PFDoDA is an individual compound from the PFAS group of substances. It belongs to the group of long-chain perfluorinated carboxylic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily through industry, PFAS-containing products, coatings, impregnations, landfill sites, sewage treatment plants, contaminated soil and groundwater. As a long-chain PFAS, PFDoDA is particularly persistent. | PFDoDA has no beneficial use in drinking water. It is problematic because it is very persistent and, as a long-chain PFAS, is more likely to accumulate in the environment, sediments and organisms than many short-chain PFAS. | Reverse osmosis membrane: highly effective and broadly active against PFAS.
Activated carbon: generally significantly more effective for long-chain PFAS such as PFDoDA than for short-chain PFAS. | True | There is no separate individual limit value for PFDoDA. However, PFDoDA is a component of the PFAS-20 total. A limit of 0.1 µg/l has applied to the sum of the 20 listed PFAS since 12 January 2026. PFDoDA does not belong to the PFAS-4 group. |
| 61 | Perfluorododecanesulfonic acid
(PFDoS) | PFDoS is an individual compound from the PFAS group of substances. It belongs to the long-chain perfluorinated sulfonic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily from industry, PFAS-containing products, coatings, impregnations, fire-fighting foams, landfill sites, sewage treatment works, contaminated soil and groundwater. As a long-chain PFAS, it can persist in the environment for a long time. | PFDoS has no beneficial use in drinking water. It is highly persistent and, as a long-chain PFAS, is more likely to accumulate in the environment, sediments and organisms than many short-chain PFAS. It is therefore undesirable in drinking water. | Reverse osmosis membrane: highly effective and broadly active against PFAS.
Activated carbon: generally significantly more effective for long-chain PFAS such as PFDoS than for short-chain PFAS. | True | There is no separate limit value for PFDoS. However, PFDoS is a component of the PFAS-20 total. A limit of 0.1 µg/l has applied to the total of the 20 listed PFAS since 12 January 2026. PFDoS does not belong to the PFAS-4 group. |
| 62 | Perfluoroheptanoic acid (PFHpA) | PFHpA is a single compound from the PFAS group of substances. It belongs to the class of perfluorinated carboxylic acids and is one of the persistent ‘forever chemicals’. | Primarily from industry, PFAS-containing products, coatings, impregnations, fire-fighting foams, landfill sites, sewage treatment works, contaminated soil and groundwater. PFHpA is relatively mobile and can spread via the water cycle. | PFHpA serves no useful purpose in drinking water. It is persistent, mobile and undesirable. As a shorter-chain PFAS, it generally accumulates to a lesser extent than long-chain PFAS, but can be more difficult to remove using conventional activated carbon. | Reverse osmosis membrane: highly effective and broadly applicable against PFAS. Activated carbon: possible, but often less reliable for shorter-chain PFAS such as PFHpA than for longer-chain PFAS. | True | There is no separate individual limit value for PFHpA. However, PFHpA is a component of the PFAS-20 total. A limit of 0.1 µg/l has applied to the total of the 20 listed PFAS since 12 January 2026. PFHpA does not belong to the PFAS-4 group. |
| 63 | Perfluoroheptanesulfonic acid
(PFHpS) | PFHpS is an individual compound from the PFAS group of substances. It belongs to the perfluorinated sulfonic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily from industry, PFAS-containing products, impregnations, coatings, fire-fighting foams, landfill sites, sewage treatment works, contaminated soil and groundwater. PFHpS can spread via the water cycle and persist in the environment for a long time. | PFHpS has no beneficial use in drinking water. It is persistent, mobile and undesirable. As a medium-chain sulphonic acid, it can bind more strongly to activated carbon than many short-chain PFAS, but remains a relevant trace substance. | Reverse osmosis membrane: highly effective and broadly effective against PFAS.
Activated carbon: generally more effective for PFHpS than for very short-chain PFAS, depending on contact time and filter design. | True | There is no separate individual limit value for PFHpS. However, PFHpS is a component of the PFAS-20 total. A limit of 0.1 µg/l has applied to the total of the 20 listed PFAS since 12 January 2026. PFHpS does not belong to the PFAS-4 group. |
| 64 | Perfluorohexanoic acid (PFHxA) | PFHxA is a single compound from the PFAS group of substances. It belongs to the short-chain perfluorinated carboxylic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily through industry, PFAS-containing products, coatings, impregnations, fire-fighting foams, sewage treatment plants, landfill sites, contaminated soil and groundwater. PFHxA is highly mobile and can easily spread throughout the water cycle. | PFHxA serves no useful purpose in drinking water. It is persistent, mobile and undesirable. Short-chain PFAS such as PFHxA generally accumulate to a lesser extent in the body than long-chain PFAS, but are often more difficult to remove using conventional activated carbon. | Reverse osmosis membrane: highly effective, particularly for mobile short-chain PFAS. Activated carbon: often less reliable for short-chain PFAS such as PFHxA than for long-chain PFAS. | True | There is no separate limit value for PFHxA. However, PFHxA is a component of the PFAS-20 total. A limit of 0.1 µg/l has applied to the sum of the 20 listed PFAS since 12 January 2026. PFHxA does not belong to the PFAS-4 group. |
| 65 | Perfluorohexanesulfonic acid (PFHxS) | PFHxS is a single compound from the large group of substances known as PFAS. It is one of the particularly relevant ‘forever chemicals’ because it is very persistent and can accumulate in the environment and the human body. | Primarily from PFAS-containing fire-fighting foams, industry, electroplating, coated products, impregnations, landfill sites, sewage treatment works, contaminated soil and groundwater. PFHxS is highly mobile and can spread via the water cycle.”,”PFHxS serves no purpose in drinking water. It is problematic because it is highly persistent, mobile and bioaccumulative. PFAS are associated, amongst other things, with potential effects on the immune system, the liver, hormone balance and development. | Reverse osmosis membrane: highly effective against PFAS across a broad spectrum.
Activated carbon: particularly effective against longer-chain PFAS such as PFHxS. | True | There is no separate individual limit value for PFHxS in the German Drinking Water Ordinance, but PFHxS is included in two total limit values: | |
| 66 | Perfluorononanoic acid (PFNA); PFNA is a single compound from the PFAS group of substances. It is a persistent perfluorinated carboxylic acid and is therefore a so-called ‘forever chemical’. | Mainly through industry, PFAS-containing products, impregnations, coatings, fire-fighting foams, sewage treatment plants, landfill sites, contaminated soil and groundwater. PFNA is highly persistent and can spread via the water cycle. | PFNA has no beneficial use in drinking water. It is problematic because it is very persistent, mobile and bioaccumulative. PFAS are associated, amongst other things, with potential effects on the liver, the immune system, hormone balance and development. | Reverse osmosis membrane: highly effective and broadly active against PFAS.
Activated carbon: particularly relevant for longer-chain PFAS such as PFNA. | True | There is no separate individual limit value for PFNA, but PFNA is included in the relevant total PFAS limit values:
PFAS-20: from 12 January 2026, 0.1 µg/l applies to the sum of 20 PFAS.
PFAS-4: from 12 January 2028, a limit of 0.02 µg/l applies to the sum of PFOA, PFNA, PFHxS and PFOS | |
| 67 | Perfluorononanesulfonic acid (PFNS); PFNS is an individual compound from the PFAS group of substances. It belongs to the perfluorinated sulfonic acids and is classified as one of the persistent ‘forever chemicals’."Mainly through industry | PFAS-containing products | impregnations | coatings | fire-fighting foams | landfill sites | sewage treatment works |
| 68 | Perfluorooctanoic acid (PFOA) | PFOA is a single compound from the PFAS group of substances. It is one of the well-known ‘forever chemicals’ because it is extremely persistent and can accumulate in the environment and the body. | Primarily through industry, products containing PFAS, coatings, impregnations, fire-fighting foams, landfill sites, sewage treatment plants, contaminated soil and groundwater. | PFOA serves no useful purpose in drinking water. It is problematic because it is persistent, mobile and bioaccumulative. PFAS are associated, amongst other things, with potential effects on the liver, the immune system, hormone balance, development and metabolism.”, “Reverse osmosis membrane: highly effective and broadly active against PFAS.
Activated carbon: particularly effective against longer-chain PFAS such as PFOA. | True | There is no separate individual limit value for PFOA in the German Drinking Water Ordinance, but PFOA is included in two PFAS total limit values:
PFAS-20: from 12 January 2026, a limit of 0.1 µg/l applies to the sum of 20 PFAS.
PFAS-4: from 12 January 2028, a limit of 0.02 µg/l will apply to the sum of PFOA, PFNA, PFHxS and PFOS.”
69,Perfluorooctane sulfonic acid (PFOS),PFOS is a single compound from the PFAS group of substances. It is one of the best-known and most critically assessed ‘forever chemicals’ because it is extremely persistent and can accumulate in the environment and the human body." | “Primarily from PFAS-containing fire-fighting foams |
| 70. Perfluoropentanoic acid (PFPeA): PFPeA is a single compound belonging to the PFAS group of substances. It belongs to the group of short-chain perfluorinated carboxylic acids and is classified as one of the persistent ‘forever chemicals’." "It is found primarily in industry | PFAS-containing products | coatings | impregnations | sewage treatment plants | landfills | contaminated soil | fire-fighting foams and groundwater. PFPeA is highly mobile and can easily spread throughout the water cycle." |
| 71 | Perfluoropentanesulfonic acid
(PFPeS) | PFPeS is a single compound from the PFAS group of substances. It belongs to the short-chain perfluorinated sulfonic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily from industry, PFAS-containing products, impregnations, coatings, fire-fighting foams, sewage treatment plants, landfill sites, contaminated soil and groundwater. As a mobile PFAS substance, PFPeS can remain in the water cycle for a prolonged period. | PFPeS serves no useful purpose in drinking water. It is persistent, mobile and undesirable. Short-chain PFAS generally accumulate to a lesser extent in the body than long-chain PFAS, but are often more difficult to remove using conventional activated carbon. | Reverse osmosis membrane: highly effective, particularly for mobile PFAS. Activated carbon: can be effective, but is often less reliable for shorter-chain PFAS than for long-chain PFAS such as PFOS or PFOA. | True | There is no separate individual limit value for PFPeS. However, PFPeS is a component of the PFAS-20 total. A limit value of 0.1 µg/l has applied to the total of the 20 listed PFAS since 12 January 2026. |
| 72 | Perfluorotridecanoic acid (PFTrDA) | PFTrDA is an individual compound from the PFAS group of substances. It belongs to the very long-chain perfluorinated carboxylic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily through industry, PFAS-containing products, coatings, impregnations, landfill sites, sewage treatment works, contaminated soil and groundwater. As a long-chain PFAS, it can persist in the environment for a long time and is more likely to bioaccumulate in organisms, sediments or soil. | PFTrDA serves no useful purpose in drinking water. It is problematic because it is highly persistent and, as a long-chain PFAS, is more prone to bioaccumulation than many short-chain PFAS. This makes it undesirable from a water safety perspective. | Reverse osmosis membrane: highly effective and broadly effective against PFAS.
Activated carbon: generally significantly more effective for long-chain PFAS such as PFTrDA than for short-chain PFAS. | True | There is no separate individual limit value for PFTrDA. However, PFTrDA is a component of the PFAS-20 total. A limit of 0.1 µg/l has applied to the total of the 20 listed PFAS since 12 January 2026. PFTrDA does not belong to the PFAS-4 group. |
| 73 | Perfluorotridecanesulfonic acid (PFTrDS) | PFTrDS is a single compound from the PFAS group of substances. It belongs to the very long-chain perfluorinated sulfonic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily from industry, PFAS-containing products, impregnations, coatings, fire-fighting foams, landfill sites, sewage treatment works, contaminated soil and groundwater. As a long-chain PFAS, it can persist in the environment for a long time and is more likely to bioaccumulate in organisms, soil or sediments.”,PFTrDS serves no useful purpose in drinking water. It is highly persistent | undesirable and | as a long-chain PFAS compound | particularly relevant because such substances tend to bioaccumulate more strongly than many short-chain PFAS." | Reverse osmosis membrane: highly effective and broadly effective against PFAS.
Activated carbon: generally significantly more effective against long-chain PFAS such as PFTrDS than against short-chain PFAS. |
| 74 | Perfluoroundecanoic acid
(PFUnDA) | PFUnDA is a single compound from the PFAS group of substances. It belongs to the long-chain perfluorinated carboxylic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily from industry, PFAS-containing products, coatings, impregnations, landfill sites, sewage treatment plants, contaminated soil and groundwater. As a long-chain PFAS, PFUnDA can persist in the environment for a long time and is more likely to bioaccumulate in organisms, soil or sediments. | PFUnDA serves no useful purpose in drinking water. It is highly persistent, undesirable and, as a long-chain PFAS, tends to bioaccumulate more readily than many short-chain PFAS. | Reverse osmosis membrane: highly effective and broadly active against PFAS.
Activated carbon: generally significantly more effective for long-chain PFAS such as PFUnDA than for short-chain PFAS. | True | There is no separate individual limit value for PFUnDA. However, PFUnDA is a component of the PFAS-20 total. From 12 January 2026, a limit of 0.1 µg/l will apply to the sum of the 20 listed PFAS. PFUnDA does not belong to the PFAS-4 group. |
| 75 | Perfluoroundecanesulfonic acid
(PFUnS) | PFUnS is a single compound from the PFAS group of substances. It belongs to the long-chain perfluorinated sulfonic acids and is classified as one of the persistent ‘forever chemicals’. | Primarily from industry, PFAS-containing products, impregnations, coatings, fire-fighting foams, landfill sites, sewage treatment works, contaminated soil and groundwater. | PFUnS has no beneficial use in drinking water. It is highly persistent and, as a long-chain PFAS, particularly undesirable because such substances tend to bioaccumulate in the environment, soil, sediments and organisms. | Reverse osmosis membrane: highly effective and broadly active against PFAS.
Activated carbon: generally significantly more effective for long-chain PFAS such as PFUnS than for short-chain PFAS. | True | There is no separate individual limit value for PFUnS. However, PFUnS is a component of the PFAS-20 total. Instead, a limit of 0.1 µg/l has applied since 12 January 2026 for the sum of the 20 listed PFAS. PFUnS does not belong to the PFAS-4 group. |
| 76 | PFAS | PFAS stands for per- and polyfluoroalkyl substances. This is a large group of substances comprising several thousand chemicals. They are often referred to as ‘forever chemicals’ because they are extremely persistent in the environment. | Primarily through industry, fire-fighting foams, coated products, impregnations, packaging, sewage treatment plants, landfill sites, contaminated soil and groundwater. Once in the environment, they hardly degrade at all and can spread throughout the water cycle. | PFAS are a cause for concern because they are highly persistent, can accumulate in the body in some cases, and are linked to various health risks, including effects on the liver, the immune system, hormone balance and development. They serve no purpose in drinking water. | Activated carbon: highly effective, particularly for longer-chain PFAS such as PFOA/PFOS.
Reverse osmosis membrane: highly effective and widely suitable for reducing many PFAS. | True | PFAS-20: from 12 January 2026, the limit will be 0.00010 mg/l, i.e. 0.1 µg/l for the sum of 20 PFAS.
PFAS-4: from 12 January 2028, the limit will be 0.000020 mg/l, i.e. 0.02 µg/l, for the sum of PFOS, PFOA, PFNA and PFHxS. |
| 77 | Mercury | Mercury is a heavy metal. It can occur in various forms, for example as inorganic mercury or in an organically bound form as methylmercury. | Primarily through industrial emissions, contaminated sites, mining, waste, contaminated soil or old technical applications. In small quantities, it can also occur naturally in rock and soil. | Mercury poses a health risk because it can adversely affect, in particular, the nervous system, the kidneys and children’s development. | Reverse osmosis membrane: highly effective in reducing dissolved heavy metals.
Activated carbon: can reduce mercury depending on its form and the type of activated carbon used, particularly with suitable specialised activated carbons. | True | 0.0010 mg/l, i.e. 1 µg/l. |
| 78 | Radon | Radon | or radon-222 | is a naturally occurring radioactive noble gas. It is produced by the decay of uranium and radium in soil and rock. | It enters groundwater primarily from rock and the subsoil. Radon is particularly relevant in the case of well water, private water supplies and regions with distinctive geological features. | Radon is radioactive. When consumed, the exposure is usually lower than via inhalation, but radon can be released from water – for example, whilst showering or cooking – and thus contribute to indoor radon exposure. | Activated carbon: can adsorb radon, but is more of a specialised application due to the potential for radioactive accumulation in the filter material.
Reverse osmosis membrane: not the typical primary technique for radon, as radon is present in gaseous or dissolved form. |
| 79 | X-ray contrast agents | X-ray contrast agents are medicinal substances used in CT and X-ray examinations to make organs, blood vessels or tissues more visible. Iodinated X-ray contrast agents such as iopamidol, iohexol, iomeprol or diatrizoate.”,”After the examination, most of it is excreted by the body. It enters rivers, lakes, bank filtrate, groundwater and, to some extent, drinking water via wastewater and sewage treatment plants. The Federal Environment Agency describes iodinated X-ray contrast agents as mobile and persistent trace substances that are regularly detected in surface waters and drinking water. | X-ray contrast agents serve no purpose in drinking water. Many of these substances are highly water-soluble, mobile and poorly biodegradable. In the short term, the traces found are generally not considered a health risk, but they are an indication of wastewater influence and undesirable micropollutants. | Reverse osmosis membrane: highly relevant, as many X-ray contrast agents are present in dissolved and mobile form. Activated carbon: may be effective depending on the substance, but is not always reliable for highly polar, mobile contrast agents. | False | The German Drinking Water Ordinance does not specify a separate limit value for X-ray contrast agents. Depending on the substance | health-based guideline values from the Federal Environment Agency may be used for assessment. |
| 80 | Acid capacity to pH 4.3 | The acid capacity to pH 4.3 describes how much acid water can absorb before the pH value drops to 4.3. It is a measure of the water’s buffering capacity.
Why is this value important?
KS 4.3 is closely related to hydrogen carbonate, carbonate hardness, alkalinity and the calcium-carbon dioxide equilibrium. A higher value usually means that the water is better able to buffer pH fluctuations. | The value is primarily of technical importance. It helps in the assessment of:
pH stability
Corrosion behaviour
Limescale formation
Calcite dissolution capacity
Suitability for pipes, fittings and water treatment
Assessment of reverse osmosis, softening and remineralisation | No. KS 4.3 is not a pollutant. However, a very low value may indicate that the water is poorly buffered and more prone to pH fluctuations or corrosion. A high value may be associated with higher carbonate hardness and limescale formation. | Reverse osmosis membrane: significantly reduces bicarbonate and, as a result, usually KS 4.3 as well. Activated carbon: does not normally have a specific effect on KS 4.3. | False | There is no specific limit value for KS 4.3 in the Drinking Water Ordinance. The value is used more for technical assessment, including in relation to corrosion and calcite dissolution capacity. Drinking water must not be corrosive; to this end, factors such as pH, conductivity, chloride, sulphate and calcite dissolution capacity are taken into account.”
81,Selenium,”Selenium is a naturally occurring trace element. In very small quantities, it is important for humans; however, in drinking water, it is not a substance that must be specifically present.”,”Primarily through natural rock and soil layers. In addition, selenium can enter groundwater or surface water via industry, mining, agriculture, fertilisers or wastewater.”,”It is essential in small quantities, but prolonged excessive intake can lead to health problems, for example affecting hair, nails, skin, the liver or the nervous system.”,Reverse osmosis membrane: highly effective at reducing dissolved trace elements and ions. Activated carbon: not usually the first choice for dissolved selenium.,True,0.010 mg/l |
| 82 | Sotalol | Sotalol is an active pharmaceutical ingredient belonging to the group of beta-blockers and antiarrhythmics. It is used | amongst other things | to treat cardiac arrhythmias. In drinking water | sotalol is an undesirable pharmaceutical trace substance. | “Primarily via human excreta | wastewater and sewage treatment plants. Pharmaceutical residues can enter water bodies via sewage treatment plants and occur there as trace substances.” |
| Reverse osmosis membrane: broadly effective against many dissolved trace substances." | False | There is no specific limit value for sotalol in the German Drinking Water Ordinance. It is not included among the standard mandatory chemical parameters listed in Annex 2. | | | | | |
| 83 | Sulphonamides | Sulphonamides are a group of active antibiotic substances. They are | or were | used in human medicine and | in particular | in veterinary medicine. In drinking water | they are undesirable pharmaceutical trace substances. |
| 84 | Total PAHs 1–6 (calculated as C) | PAH stands for polycyclic aromatic hydrocarbons. This is a group of organic pollutants that are primarily produced during incomplete combustion. ‘Total PAH’ does not refer to a single substance, but to the combined concentration of several PAHs. Important: In the Drinking Water Ordinance, the total PAH is calculated from the following substances: benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(ghi)perylene and indeno(1,2,3-cd)pyrene. Benzo(a)pyrene also has its own separate limit value.”,“Primarily from contaminated sites, industry, exhaust fumes, soot, tar-containing materials, contaminated soil or old coatings/materials in contact with water.”, “Many PAHs pose a health risk; some are classified as carcinogenic or potentially carcinogenic.”,Activated carbon: highly effective | as PAHs are organic | hydrophobic substances that can be readily adsorbed. | | | |
| Reverse osmosis membrane: can also contribute to reduction." | True | The Drinking Water Ordinance specifies a limit value of 0.00010 mg/l, i.e. 0.1 µg/l, for the total PAHs. | | | | | |
| 85 | Total PPPs; PPP stands for plant protection products. This refers to the total of all detected and quantified active substances in plant protection products and biocidal products present in drinking water. This may also include relevant degradation products. | Primarily from agriculture, plant protection, biocides, contaminated soil, surface water, groundwater and runoff following rainfall. | An individual substance may be below the limit value, but several substances together result in a total load. That is why, in addition to individual limit values, there is also a total limit value.”, “Activated carbon: highly effective for many organic pesticides.
Reverse osmosis membrane: highly effective against a wide range of dissolved residues.”,True,”Total: 0.00050 mg/l, i.e. 0.5 µg/l.”
86,Total tetrachloroethene and trichloroethene,”Tetrachloroethene and trichloroethene are chlorinated solvents. They were, or are, used primarily in industry, metal degreasing, dry cleaning and technical processes. | Mostly due to contaminated sites, leaking plant, industrial discharges, contaminated soil or polluted groundwater. | Both substances pose a health risk and serve no purpose in drinking water. A particular problem is that they can persist in soil and groundwater for relatively long periods and are frequently associated with contaminated sites. | Activated carbon: highly relevant, as both substances are organic chlorinated solvents.
Reverse osmosis membrane: can contribute further to their reduction. | True |
| 87 | Total trihalomethanes | Trihalomethanes, or THMs for short, are disinfection by-products. These include, amongst others, chloroform, bromoform, dibromochloromethane and bromodichloromethane. | They are primarily formed when water is treated with chlorine or chlorine-based disinfectants and organic matter is present in the water. | THMs serve no useful purpose in drinking water. They are an undesirable by-product of disinfection and are considered a health concern, particularly with prolonged exposure. | Activated carbon: highly effective, as THMs are organic compounds and can be readily adsorbed.
Reverse osmosis membrane: can also help to reduce levels. | True | The Drinking Water Ordinance sets a limit value of 0.050 mg/l, i.e. 50 µg/l, for the total concentration of trihalomethanes. |
| 88 | Temperature during titration KS 4.3 | The ‘temperature during titration KS 4.3’ is not a water constituent in its own right, but rather a measurement or accompanying parameter. It indicates the temperature at which the acid capacity up to pH 4.3, or KS 4.3 for short, was determined. | KS 4.3 describes how much acid is required to titrate the water to a pH value of 4.3. Above all, the value indicates the water’s buffering capacity, i.e. how well the water can counteract pH fluctuations.
KS 4.3 is particularly important for:
carbonate hardness
hydrogen carbonate content
pH stability
Calcium-carbonate equilibrium
Corrosion behaviour
Suitability for water treatment and reverse osmosis systems | No. The temperature during titration is not a contaminant and does not pose a quality issue. It serves only to ensure the correct evaluation of the laboratory result. | Reverse osmosis membrane: significantly reduces bicarbonate and thus usually KS 4.3 as well. Activated carbon: does not normally alter KS 4.3 in a targeted manner. | False | For ‘temperature during KS 4.3 titration’, there is no limit value in the Drinking Water Ordinance.”
89, Tetrachloroethene, “Tetrachloroethene, also known as perchloroethylene or PCE, is a chlorinated solvent. It has been, and continues to be, used primarily in dry cleaning, metal degreasing and industrial processes. |
| 90 | TOC | TOC stands for Total Organic Carbon. It is not a single substance, but a total value for organic substances in water. | It originates from natural organic matter in soil, plant residues, humic substances and surface water, but also from wastewater, agriculture, industry, biofilm, treatment residues or organic contaminants. | TOC is usually not a direct indicator of pollution, but an important indicator parameter. Elevated levels may indicate organic contamination, biofilm, pollution or treatment problems. Furthermore, organic substances can form undesirable by-products during disinfection, e.g. trihalomethanes. | Activated carbon: highly effective for many organic substances.
Reverse osmosis membrane: broadly reduces many dissolved organic and inorganic substances. | True | The Drinking Water Ordinance does not specify a fixed numerical limit for TOC |
| 91 | Tribromomethane | Tribromomethane, also known as bromoform, is a trihalomethane (THM for short). It is an undesirable disinfection by-product. | It can form when drinking water is treated with chlorine or chlorine-based disinfectants and organic substances and bromide are present in the water at the same time. | Tribromomethane serves no useful purpose in drinking water. It is regarded as a disinfection by-product that is harmful to health and is therefore subject to limits alongside other THMs. | Activated carbon: highly relevant, as THMs are organic compounds and can be readily adsorbed.
Reverse osmosis membrane: can also help to reduce levels. | True | There is no separate limit value for tribromomethane alone. It is included in the total for trihalomethanes. The limit is 0.050 mg/l, i.e. 50 µg/l, for the total of chloroform, bromodichloromethane, dibromochloromethane and tribromomethane. |
| 92 | Trichloroethene | Trichloroethene, also known as trichloroethylene or TCE, is a chlorinated solvent. It was primarily used for metal degreasing, cleaning and in industrial processes. | Mostly through industrial discharges, contaminated sites, leaking installations, contaminated soil or polluted groundwater. It is not a naturally occurring component of drinking water. | Trichloroethene poses a health risk and is classified as carcinogenic or potentially carcinogenic. It serves no purpose in drinking water and should ideally not be present. | Activated carbon: highly relevant, as trichloroethene is an organic solvent.
Reverse osmosis membrane: can also help to reduce levels.”,True,”Under the German Drinking Water Ordinance, the limit value for the sum of trichloroethene and tetrachloroethene is 0.010 mg/l, i.e. 10 µg/l.”
93,Trichloroethene ,Trichloroethene | also known as trichloroethylene or TCE | is a chlorinated solvent. It was primarily used in industry for metal degreasing |
| 94 | Trichloromethane | Trichloromethane, also known as chloroform, is a trihalomethane (THM for short). It is an undesirable disinfection by-product. | It is formed primarily when drinking water is treated with chlorine or chlorine-based disinfectants and organic substances are present in the water.”, “Trichloromethane serves no useful purpose in drinking water. It is considered harmful to health and is therefore subject to limits alongside other THMs. Long-term exposure via drinking water is of particular concern.,Activated carbon: highly effective | as THMs are organic compounds and can be readily adsorbed. | | | |
| Reverse osmosis membrane: can also help to reduce levels." | True | There is no separate limit value for trichloromethane alone. It is included in the total for trihalomethanes. The limit is 0.050 mg/l, i.e. 50 µg/l, for the total of trichloromethane, bromodichloromethane, dibromochloromethane and tribromomethane. | | | | | |
| 95 | Trifluoroacetic acid (TFA) | Trifluoroacetic acid, or TFA for short, is a very small, water-soluble and extremely long-lived chemical. It is classified as a highly persistent and highly mobile substance. This means that it is hardly degraded in the environment and moves easily with water through soil, rivers and groundwater. | TFA is formed, amongst other things, as a degradation product of fluorinated chemicals, for example from certain refrigerants, plant protection products, industrial chemicals and other PFAS-like precursors. It can enter the water cycle via the air, rain, surface water, wastewater, agriculture and industry. | TFA is notable not so much for its acute toxicity, but primarily for its extreme persistence and mobility. Once in the water cycle, it is very difficult to remove. The Federal Environment Agency states that TFA cannot be removed in practice using conventional water treatment methods and that its release should be avoided as far as possible. | Reverse osmosis membrane: one of the most relevant domestic technologies, but TFA poses a challenge due to its small molecular size and high mobility. Activated carbon: generally not reliable for TFA, as TFA is highly mobile and hardly binds to activated carbon. | | There is currently no standard limit value for TFA in the Drinking Water Ordinance. However |
| 96 | Uranium | Uranium is a naturally occurring heavy metal. In drinking water, its chemical effects are particularly relevant, rather than its radioactivity. | Uranium can leach from rock and soil layers and thus enter groundwater. It is particularly relevant in certain geological regions or in well water. | Uranium can place a strain on the kidneys in particular if ingested in elevated amounts over a prolonged period. | “Reverse osmosis membrane: highly effective for reducing uranium and other dissolved metals/ions. | | |
| Activated carbon: not usually reliable enough for dissolved uranium.” | True | ”0.010 mg/l | i.e. 10 µg/l.” | | | | |
| 97 | Vinyl chloride | Vinyl chloride is a chemical compound used primarily in the manufacture of PVC plastics. | Possible sources include plastics and materials in contact with water, industrial contamination sites or contaminated groundwater. It can also form as a degradation product of certain chlorinated solvents.”,Vinyl chloride is classified as carcinogenic,”Activated carbon: highly relevant, as vinyl chloride is an organic substance.
Reverse osmosis membrane: can contribute further to reduction. | True | 0.00050 mg/l, i.e. 0.5 µg/l. | | |
| 98 | | | | | | False | |
Please complete your information below to login.
Sign In
Create New Account