RO Water Purifier Repair: Common Problems and Their Solutions

Most RO purifiers give years of good service, but every machine eventually shows a fault. The good news is that nearly all problems come from a small set of parts: filters, the membrane, the pump, the adaptor (SMPS) and a few valves. Knowing the symptom helps you describe the problem clearly and helps the technician fix it in one visit.

Here are the most common water purifier repair problems we see, what usually causes them and what the fix involves.

1. No water or very little water

Likely causes: no input water or low pressure, choked pre-filters, a blocked membrane, a faulty solenoid valve, a failed pump or adaptor, or a stuck float valve in the tank.

Fix: first check that the inlet valve is open and that tap water is flowing. If it is, the technician will trace the fault stage by stage. Read our full guide to an RO not dispensing water.

2. Water leaking from the purifier

Likely causes: loose push-fit connectors, a cracked filter housing, a worn O-ring, a damaged pipe or an overflowing tank because the float valve does not shut off.

Fix: close the inlet valve and switch off the power straight away. Leaks are usually quick to fix once the source is found. See why your RO is leaking.

3. Salty, bitter or bad-tasting water

Likely causes: an exhausted RO membrane (TDS rises), a used-up carbon filter (taste and smell return), a wrongly set TDS controller or a dirty storage tank.

Fix: a TDS test shows whether the membrane is still rejecting salts. Changing the post-carbon filter and cleaning the tank often fixes taste on its own. Our article on why RO water tastes different covers this in depth.

4. Loud noise or continuous running

Likely causes: the pump working against a blocked filter, air in the line, a worn pump head, or a faulty float or high-pressure switch that never tells the pump to stop.

Fix: a purifier that never stops running wastes water and wears out the pump. Switch it off at the wall and book a check.

5. The purifier will not switch on

Likely causes: a failed adaptor (SMPS), a loose wire, a blown fuse in the socket, or a power surge that damaged the electronics.

Fix: check the socket with another appliance. If the socket works, the technician will test the SMPS and replace it if needed. A stabiliser or surge protector helps in areas with frequent voltage fluctuations.

6. UV light or indicator not working

Likely causes: the UV lamp has reached the end of its life (commonly around a year of use), or the UV choke has failed.

Fix: replace the lamp or choke. Do not keep using an RO + UV purifier with a failed UV lamp if your water source has bacterial risk.

7. Water drains continuously

Likely causes: a faulty solenoid valve or check valve, or a missing flow restrictor.

Fix: replacing the valve stops the waste and protects the membrane.

What you can safely check yourself

• Is the inlet valve open and is tap water flowing?
• Is the purifier plugged in and is the socket working?
• Is the tank tap or dispenser fully closed when not in use?
• When were the filters last changed?

Anything beyond these checks, such as opening housings, changing the membrane or working on the electricals, is best left to a trained technician.

How RO Trust handles a repair

A technician diagnoses the fault, explains what has failed and quotes the price of the parts and labour before starting. Spare parts are tested on the spot. See our RO repair service for details.

Frequently asked questions