Sediment, carbon and membrane filters have different lifespans. A maintenance calendar, warning signs and the risks of delaying replacement.
Once installed, a reverse osmosis unit works quietly, so it is easy to forget maintenance. Yet once filters are exhausted, the unit not only stops purifying but may even become a source of contamination. The calendar below is a general guide for a typical five-stage unit.
Stage 1 – Sediment (PP) filter: 6 months
It traps coarse particles such as sand, rust and dust. Depending on mains turbidity it clogs within three to six months. If delayed, flow drops and later stages foul quickly too.
Stage 2 – Granular activated carbon: 6-12 months
It retains chlorine, odour and organic contaminants. If chlorine reaches the membrane it damages the polymer and the membrane suffers irreversible harm; the carbon filter is therefore the membrane's protector.
Stage 3 – Block carbon: 6-12 months
It retains finer particles and residual chlorine. It is best replaced together with stage 2.
Stage 4 – RO membrane: 24-36 months
The heart of the unit. Its life varies with the TDS and hardness of the mains water: 18-24 months in hard water areas and up to 36 months in soft water areas. If outlet TDS has risen 20-30% from the start, the membrane needs replacing.
Stage 5 – Post carbon: 12 months
It polishes the taste of water leaving the tank. Replace it yearly.
An annual maintenance example
- Month 6: sediment filter, tank air pressure check
- Month 12: all pre-filters + post carbon + system sanitising
- Month 24: pre-filters + membrane check (TDS measurement)
- Month 36: membrane + all filters
How do you know maintenance is due?
- Water from the tap has slowed or drips.
- The taste or smell of the water has changed.
- The unit makes a constant water-running sound (membrane or valve fault).
- A TDS meter reads high.
The risks of delay
Bacteria may begin to colonise expired filters, and early membrane failure raises costs. Not neglecting annual maintenance extends unit life beyond ten years.
Zülal Su Teknolojileri customers receive SMS reminders at 6, 12 and 24 months. Through the online booking system you can schedule same-day or next-day service at your nearest service point.
The service contract advantage
Customers with an annual maintenance contract receive the filter set and technician visit at a fixed price, and the team calls you when it is due. Contracted units also carry a 24-hour response commitment for urgent faults. This provides both planning and budget predictability.
When travelling or away from home for long periods, close the unit's tap and on return drain the first litre to restart the system.