Reverse osmosis system repair: slow flow, leaks and a drain that never stops

Reverse Osmosis Company is an independent referral service, not an installer or plumber. When you send the form, your details go to an independent local water treatment pro who can contact you and prepare a quote.

First: if it is leaking

A leak under the sink comes before everything else on this page. Close the system’s own shut-off if you can find it, or the cold water valve under the sink that feeds it. Put a towel or a tray under the drip, keep electrical items away from the water, and take a photo of where the water is coming from. Then send the form and choose ‘RO repair or leak’.

How an RO system works, in one paragraph

Knowing the parts makes the symptoms easier to read. The EPA’s WaterSense program describes reverse osmosis as pressure forcing water through a semi-permeable membrane. Treated water, the permeate, goes to the RO faucet, through a storage tank on systems that have one. Reject water, the concentrate or brine, goes down the drain. Before the membrane sit pre-filters, and after it a post filter. A fault in any of these shows up at the faucet or under the sink. For the long version, read how reverse osmosis works.

The signs, and what a pro may look at

None of the lists below is a diagnosis. They are the parts a pro may check for each sign, so that you can describe the problem clearly and follow what they find.

Slow flow, or the faucet runs out of water

People ask search engines why their RO system is running out of water. The faucet gives a strong stream for a moment and then dribbles, or it never gets going. Things a pro may look at:

• Pre-filters or the membrane past the maker’s change schedule.
• The water pressure reaching the system, since RO depends on pressure to push water through the membrane.
• The storage tank, on systems that have one, and whether it fills and holds pressure.
• Kinked tubing or a partly closed valve on the supply.

A drip or a leak in the cabinet

Water on the cabinet floor can come from a filter housing, a fitting, the tubing, the faucet base or the drain connection. Things a pro may look at:

• The housings and their seals, especially after a recent filter change.
• Push-fit or compression fittings that have loosened or cracked.
• Tubing that has been pinched, rubbed or pulled out of a fitting.
• The drain connection and the faucet’s own connections.

The drain runs all the time

Some water going to the drain while the system makes water is normal: that is the concentrate. The EPA says a typical point-of-use system sends five gallons or more down the drain for every gallon of treated water, some inefficient units up to 10. Water that keeps running to the drain after the system should have stopped is not normal. Things a pro may look at:

• The parts that tell the system when to stop making water.
• The storage tank, on systems that have one.
• The drain connection itself.

If the system is old and inefficient by design, the fix may be a newer unit. A WaterSense labeled RO system must send 2.3 gallons or less to the drain per gallon treated. See reverse osmosis waste water.

The taste or smell is back

If the RO water starts to taste like plain tap water again, or picks up a new taste or smell, something in the treatment train is no longer doing its job. Things a pro may look at:

• Filters or the membrane past the maker’s schedule.
• A seal or fitting that lets water bypass a stage.
• The post filter and the storage tank, on systems that have one.
• Whether your source water has changed. If you are on a well, a new test is worth doing.

Noise, or a faucet that drips

Gurgling at the sink, a faucet that will not shut off fully, or a faucet loose on the counter are all worth mentioning when you ask. They are small, but a pro checking one part may find the cause of another.

Safe checks before you ask

These checks need no tools and touch nothing under pressure:

1. Note when the filters and membrane were last changed. A label in the cabinet or a receipt helps.
2. Check that the valve feeding the system is fully open.
3. Look along the tubing for kinks or anything resting on it.
4. Check whether the other taps in the house have normal pressure.
5. Take photos of the system, the label on the housings and anything wet.

Leave opening housings, cutting tubing and pulling fittings to someone who does that work, unless you know the system well. A housing opened under pressure, or a fitting pulled the wrong way, can turn a slow drip into a wet floor.

Repair, service or replace?

Three outcomes are possible when a pro looks at a misbehaving system, and a straight quote says which applies:

Outcome	When it fits
Service	The filters or membrane are due. A filter and membrane change may be all it needs. See RO maintenance.
Repair	A part has failed: a fitting, a seal, tubing, a valve, the faucet or the tank.
Replace	The system is old, its parts are hard to find, or it sends far more water to the drain than a newer unit would. See RO installation.

Ask the pro to explain which one they recommend and why, and to put it in writing. You can accept or turn down any quote.

What to tell the pro

• The sign: slow flow, a leak, a running drain, a taste or a noise.
• When it started, and whether anything changed around then, such as a filter change or plumbing work.
• The brand and model if you can see them, and when the filters were last changed.
• City water or a private well.
• Whether the system feeds a refrigerator or ice maker as well as the faucet.

The form takes your name, phone, ZIP code and what you need. On the contact page there is room for notes.

Will a repaired system still remove what it did?

The EPA says RO systems can potentially remove water contaminants such as lead, volatile organic compounds, PFAS, arsenic, bacteria and viruses. What a given system removes depends on the system and its certification. NSF/ANSI 58 is the standard for reverse osmosis drinking water treatment systems. If you bought the system for a particular contaminant, ask the pro whether the replacement parts keep it working to the certification it was sold with, and use the maker’s own parts where the maker says to.

Reverse osmosis repair near you

Keeping the next repair away

Some repairs start with upkeep that slipped. Keep a dated label in the cabinet for every filter and membrane change, follow the maker’s schedule, and look under the sink now and then for damp spots, especially in the days after a change. If you are on a private well, keep testing it every year, as the EPA advises, so that a change in the water does not surprise the system.

Send the form with your ZIP code and your request goes to an independent RO pro who works in your area. Asking is free, and there is no obligation to go ahead. If you would rather understand the upkeep that prevents many of these problems, read reverse osmosis maintenance, or see how this site works.

Questions people ask