💧 Water guide

Water Purifier Maintenance Guide: Schedules, Costs & Warning Signs

8 min readPublished 26 February 2026Updated 1 August 2026

The maintenance schedule

Component	Replace every	Indicative cost	What happens if you skip it
Sediment pre-filter	6-12 months	₹150 - ₹400	Sediment reaches and abrades the membrane
Activated carbon pre-filter	6-12 months	₹250 - ₹600	Chlorine oxidises and destroys the RO membrane
RO membrane	12-24 months	₹1,200 - ₹3,500	TDS rejection falls; contaminants pass through
UV lamp	12-18 months	₹500 - ₹1,500	No microbiological protection, silently
Post-carbon / polisher	12 months	₹250 - ₹600	Taste deteriorates
Mineral / copper / alkaline cartridge	12 months	₹500 - ₹1,500	Loses its function
Tank sanitisation	12 months	Usually included in service	Biofilm develops in the tank

Why pre-filters are the most important ₹500 you spend

This is the single most valuable thing to understand about purifier maintenance. Your carbon pre-filter's job is to remove chlorine before it reaches the RO membrane, because chlorine chemically attacks the membrane's thin-film polyamide layer. An exhausted carbon filter therefore does not just stop working — it actively allows your ₹3,000 membrane to be destroyed.

The same applies to the sediment filter, which prevents particles from abrading the membrane surface. Both cost a few hundred rupees. Both, if neglected, turn into a membrane replacement.

So if your budget is tight, change pre-filters on schedule and stretch the membrane. Never the other way round.

Important

The most expensive maintenance mistake is skipping cheap pre-filters to save money, then replacing the membrane twice as often. It costs several times more.

Warning signs, and what each means

Output TDS rising → membrane degrading, or seal bypass. This is your primary indicator; log it monthly.
Water flow slowing → clogged pre-filters or fouled membrane, or low input pressure.
Purifier running constantly → leaking tank, faulty float valve, or failed auto-cut-off.
Water tastes or smells odd → exhausted carbon filter or tank biofilm.
Visible particles → failed sediment filter or damaged UF membrane.
Purifier stopped entirely (Pureit) → germkill kit expired and the safety lock engaged. This is intentional.

AMC: what to pay and what to watch for

A reasonable domestic AMC costs ₹2,500-₹4,500 a year including all consumables and two to three visits. Franchisee pricing varies widely between cities for the same service, so it is worth getting the quote in writing and comparing.

The upsell pattern to be aware of: a technician declares your membrane needs replacing at every visit. Ask him to show you the input and output TDS readings first. If output TDS is still low relative to input, the membrane is working and does not need replacing regardless of how long it has been installed.

Keep your own log of input TDS, output TDS and service dates. Owners who can produce a log get materially better service outcomes, because it makes vague diagnoses harder to sustain.

Get the AMC inclusion list in writing, itemised by part.
Confirm whether the RO membrane is included or charged separately — this is the most common exclusion.
Ask how many visits are included and what the response time is for a breakdown.
Insist the technician records input and output TDS at every visit, on the service slip.

Frequently asked questions

How often should I change my RO filter?

Sediment and carbon pre-filters every 6-12 months, the RO membrane every 12-24 months (sooner on high-TDS input), the UV lamp every 12-18 months, and the post-carbon polisher annually. Change pre-filters on time above all else — an exhausted carbon filter lets chlorine through and destroys the far more expensive membrane.

What is the annual maintenance cost of a water purifier in India?

Budget ₹2,500-₹4,500 a year for a domestic RO purifier including all consumables and two to three service visits. Copper, alkaline or hot-water models cost more because of extra cartridges. AMC quotes above ₹5,000 for a standard domestic unit are worth questioning, and franchisee pricing varies significantly between cities.

How do I know if my RO membrane needs replacing?

Measure input and output TDS with a meter. If output TDS has risen substantially compared with your baseline while input is unchanged, the membrane is degrading. If flow has dropped but rejection is still good, it is more likely fouling or clogged pre-filters. Do not accept a membrane replacement recommendation without seeing the TDS readings.

Can I change RO filters myself?

Sediment and carbon cartridges are straightforward on most models with a filter spanner, and doing it yourself saves labour cost. The RO membrane and UV lamp are better left to a technician — membranes need correct seating and o-ring placement to avoid bypass, which produces water that looks fine while not being purified. If your unit is under warranty, self-servicing may void it.