Reverse osmosis system repair: slow flow, constant draining and taste faults

Advertised prices, verified

Diagnosing the classic RO faults

1. Slow flow from the faucet. Check the storage tank's air charge first: a waterlogged tank with a failed bladder delivers a glass and then dribbles. If the tank holds charge, suspect clogged prefilters, an exhausted membrane, or low incoming pressure. Work from the cheapest suspect toward the membrane.
2. Water running to the drain constantly. Continuous hissing at the drain means the automatic shutoff valve or check valve is not closing when the tank fills. Both are inexpensive inline parts. Left unfixed, the system quietly wastes water around the clock, so this repair pays for itself quickly.
3. Taste or odor returning. Bad taste after a period of good water points at the postfilter first, then a spent membrane, then a storage tank due for sanitizing. Replace the carbon postfilter, sanitize the tank during the change, and take a TDS reading: a high reading after the membrane confirms the membrane itself.
4. Leaks under the sink. Trace the drip to its source: a push-fit tube not seated fully, a cracked fitting, a loose filter housing, or the drain saddle. Push-fit connections want the tube cut square and pushed firmly home. Persistent weeping from a housing thread means a new O-ring or housing, both standard parts.

Repair or replace: the RO math

Membranes, filters, shutoff valves, check valves, flow restrictors and storage tanks are all standard replaceable parts, and an RO system can be rebuilt around its manifold almost indefinitely. Repair wins while the housing platform and its cartridge sizes remain in production.

When the manifold itself cracks, the brand's cartridge format is discontinued, or years of skipped sanitizing make a fresh start attractive, the published system prices in the table above are the comparison. Complete replacement also resets every consumable at once, which simplifies the schedule going forward.

Keeping the repaired system healthy

Most RO faults are downstream of skipped maintenance: prefilters left too long starve the membrane and shorten its life, and an unsanitized tank grows the tastes people blame on the membrane. Fixing the schedule fixes the recurrence, not just the symptom.

Hard feed water is the other silent killer, scaling the membrane and cutting output. If your supply is hard, softening upstream protects the repair you just paid for; our water softener cost page covers what that protection involves.

Common questions

Why does my reverse osmosis system run all the time?

The automatic shutoff or check valve is failing to close once the storage tank is full, so water keeps flowing to the drain. Both are cheap inline parts and replacing them is a standard, quick repair.

Why is my RO water flow so slow?

In order of likelihood: a waterlogged storage tank with a failed air bladder, clogged prefilters, an exhausted membrane, or low feed pressure. The tank and prefilters are quick checks before spending on a membrane.

How do I know the RO membrane needs replacing?

A TDS meter tells you in seconds: compare the reading at the RO faucet against the tap water. When the RO reading climbs toward the tap reading despite fresh prefilters, the membrane is passing dissolved solids and is due.

Is RO repair a DIY job?

Mostly yes: filters, membrane, shutoff valve and tank are all push-fit or hand-threaded parts designed for owner service. The drain saddle and faucet-side work under the sink deck are the steps where some owners prefer a tech.

Browse by system type

• Compare Water softeners on advertised prices
• Compare Salt-free softeners on advertised prices
• Compare Whole-house filters on advertised prices
• Compare Reverse osmosis systems on advertised prices
• Compare Shower filters on advertised prices
• Compare Countertop filters on advertised prices
• Compare Refrigerator filters on advertised prices
• Compare Iron filters on advertised prices