Your RO is dispensing slowly — the usual causes, in order

Does this match your symptoms?

• Water trickles from the faucet even when the tank shows full
• Tank takes much longer to fill than it used to
• Flow starts strong then fades within a few seconds
• Flow improved briefly after the last service, then fell away again

Work through the causes in this order

Ordered by how often each turns out to be the real cause — not by what it costs to fix. 1 of these costs nothing to resolve.

1. Most commonYou can fix thisFree to fix

   1. Tank valve partly closed

   How to confirm it

   Free to check, so check it first. Find the valve on the tank outlet and confirm it is fully open. It is routinely left partly closed after a service visit, and it produces exactly the 'full tank, weak flow' symptom people assume must be a dead membrane.

   The fix

   Open the valve fully. That is the whole fix, and it is why this is at the top of the list rather than buried under parts we could sell you.

   Part: None — free to fix

2. Most commonTechnician job₹300 – ₹1,800

   2. Flat tank bladder (lost air charge)

   How to confirm it

   Classic signature: strong initial spurt that fades to a dribble after a few seconds, and a tank that feels heavy and sloshy when rocked. Pressurised tanks hold an air charge behind a bladder; when it leaks away there is nothing left to push the water out.

   The fix

   Drain the tank fully and re-pressurise the air side to the manufacturer's figure — typically around 7-8 psi with the tank empty. If it will not hold the charge, the bladder has failed and the tank needs replacing.

   Part: Re-pressurisation, or replacement tank if the bladder has gone

3. CommonYou can fix this₹350 – ₹800

   3. Choked sediment or carbon pre-filter

   How to confirm it

   This is the cause when the tank is slow to FILL rather than slow to dispense. Open the first-stage housing: a brown or grey cartridge is choked. Note the colour through the full depth, not just the outer surface.

   The fix

   Replace the sediment and carbon cartridges. If they are choking within a few months, add a pre-filter upstream — it is cheaper than the cartridges you are getting through.

   Part: Sediment and carbon cartridges

4. CommonTechnician job₹1,500 – ₹3,500

   4. Fouled or ageing RO membrane

   How to confirm it

   Membranes lose throughput gradually over two to four years, which is normal ageing rather than a fault. Suspect fouling instead when the decline was rapid, or when output TDS has risen at the same time as flow has fallen. Check both together — flow alone does not distinguish ageing from fouling.

   The fix

   Replace the membrane. Change the pre-filters at the same time, since a choked pre-filter is the usual reason a membrane fouls early.

   Part: RO membrane

5. OccasionalYou can fix thisUp to ₹200

   5. Kinked or crushed tubing

   How to confirm it

   Trace the 1/4-inch tubing from the unit to the tank and to the faucet. Kinks form where the unit has been pushed back against a wall, and they are easy to miss because the crush point is usually behind the machine.

   The fix

   Re-route the tubing, or cut out the damaged section and refit with a push-fit connector. A few rupees of tube.

   Part: Tubing, if a section needs replacing

When to stop and call a technician

• The tank will not hold its air charge after re-pressurisation
• Flow is slow and output TDS has risen at the same time
• You have replaced the pre-filters and flow did not improve

Costs shown are indicative bands for India, published so you can sanity-check a quote — they are not quotations, and they vary by brand, city and whether the technician is brand-authorised. Last reviewed 2026-08-08.