Your RO purifier is making a noise — what each sound tells you

Does this match your symptoms?

• Pump noticeably louder than it used to be
• Knocking or hammering when the unit stops
• Machine runs continuously and never falls silent
• Buzzing with no water flowing
• Gurgling from the drain line

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 commonTechnician job₹350 – ₹900

   1. Machine never cutting off

   How to confirm it

   If the pump runs continuously rather than filling and stopping, the auto-cut-off switch or float has failed. Confirm by checking whether the drain line still flows when the tank is full.

   The fix

   Repair or replace the auto-cut-off assembly or float switch. Treat this as urgent — a machine that never stops rejects water around the clock and wears the membrane and pump prematurely.

   Part: Auto cut-off switch / float

2. Most commonYou can fix thisFree to fix

   2. Loose mounting or tubing against a panel

   How to confirm it

   Press gently on the unit while it is running. If the noise changes or stops, it is transmitted vibration rather than a mechanical fault. Very common on wall-mounted units and on machines inside a closed cabinet.

   The fix

   Tighten the mounting, and pad any tubing touching a panel with foam or a cable tie standoff. Free, and it is the most over-diagnosed noise complaint in the category.

   Part: None — free to fix

3. CommonYou can fix this₹150 – ₹2,500

   3. Pump starved by low inlet pressure

   How to confirm it

   A pump running dry or against inadequate supply gets noticeably louder and rougher. Check inlet flow by timing a one-litre fill from the feed tap, and check the sediment filter, which throttles the pump when choked.

   The fix

   Replace a choked sediment filter, or fit a booster pump if supply pressure is genuinely inadequate.

   Part: Sediment cartridge, or booster pump

4. CommonTechnician job₹200 – ₹600

   4. Failing check valve — hammering on shutdown

   How to confirm it

   A distinct knock or hammer at the moment the unit stops usually means the non-return valve is not closing cleanly, letting pressurised water surge back.

   The fix

   Replace the check valve. A small part and a straightforward job for a technician.

   Part: Check / non-return valve

5. OccasionalTechnician job₹350 – ₹700

   5. Solenoid valve buzzing

   How to confirm it

   An electrical buzz with no water movement points at the solenoid coil. Often accompanied by the tank failing to fill.

   The fix

   Replace the solenoid valve.

   Part: Solenoid / SV valve

6. OccasionalTechnician job₹1,200 – ₹2,500

   6. Worn pump

   How to confirm it

   A grinding or rattling pump, as distinct from a loud but smooth one, usually means worn internals. Typically appears after several years of service, and often alongside reduced output.

   The fix

   Replace the pump. Ask the technician to confirm inlet pressure is adequate first — a pump starved by low supply will fail the same way again.

   Part: Booster pump

When to stop and call a technician

• The unit runs continuously and never cuts off
• Hammering on shutdown, which stresses every joint in the system
• Any burning smell or electrical buzzing — stop and unplug immediately
• Grinding from the pump

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.