When do I need to change the filters in my reverse osmosis system? Intervals and warning signs
A reverse osmosis (RO) system only produces clean water if its filters are changed in good time. Here you can find out which filters need changing and when, how to tell if a filter is overdue for replacement, and why missing a change ends up costing more than it saves.
Summary
- For The Local Water systems, the following applies: Core+ OS every 6 months, Core M OS every 12 months, the membrane every 3–8 years (TLW 2 and TLW 4) or on average every 5–8 years (TLW 7).
- These replacement intervals apply even if you use very little water – over time, bacteria can build up in a damp carbon filter.
- Warning signs: a change in taste or smell, a significant reduction in flow rate, or a rising TDS value.
- With the Filterservice, replacement filters are delivered automatically at the right time.
1. The filter stages and their replacement intervals
| Filter | Function | Replacement | Price |
|---|---|---|---|
| Core+ OS (activated carbon block, first stage) | removes particles, chlorine, odours and organic substances and protects the membrane | every 6 months | Rp1,200,000 |
| Core M OS (activated carbon block with capillary membrane, post-filter after the membrane) | protects against recontamination and improves the taste | every 12 months | Rp2,200,000 |
| TLW X membrane (TLW 2, TLW 4) | retains the majority of dissolved substances | every 3–8 years, depending on water quality and usage | Rp6,000,000 |
| TLW 7 membrane | retains the majority of dissolved substances | on average every 5–8 years, often lasting over 10 years | – |
How long the membrane lasts depends primarily on how hard and contaminated your tap water is, and how reliably the pre-filters are replaced.
2. Why the replacement intervals apply even with low usage
An activated carbon filter is constantly damp and traps organic substances. Over time, bacteria can multiply inside it – regardless of how much water passes through. That is why replacement is based on time, not just on the volume of water. This is particularly true in Indonesia’s warm climate.
3. Warning signs that a filter is due for replacement
- Changes in taste or smell, e.g. a slight taste of chlorine: the activated carbon filter is worn out.
- Significantly less water is coming out of the tap, even though the water pressure remains the same: the pre-filter or membrane is clogged.
- The TDS level of the filtered water rises slowly over several weeks: the membrane is deteriorating. Check this from time to time with a TDS meter – on the TLW 7, the display shows the conductivity directly.
4. What happens if you miss the replacement deadline?
If the activated carbon block is exhausted, chlorine from the tap water reaches the membrane. The membranes commonly used in RO systems (thin-film composite membranes) are permanently damaged by chlorine. Failing to change the pre-filter, which costs Rp1,200,000, can therefore result in the premature replacement of the membrane, costing Rp6,000,000.
5. Filterservice: never have to think about replacing it again
When you buy a system, the Filterservice is included: the Core+ OS is delivered to you automatically every 6 months, and the Core M OS every 12 months. The first appointment is scheduled at the time of purchase, and you can cancel the service at any time. You carry out the replacement yourself, without any tools: unscrew the casing by hand, remove the old cartridge, insert the new one – done.
Conclusion
Change the filters according to the schedule, not just when the water starts to taste bad. This protects your health and the expensive membrane. Any questions about changing the filters? Message us on WhatsApp – if you’d like, we can help you via video call.