The Definitive Reverse Osmosis System Repair Guide

Posted by Donavan Jones on

Are You Ready To Have Filtered Water? Let's Get Started!


technician installing a RO systemThank you for taking the time to read our Reverse Osmosis System Repair Guide. Read through this reverse osmosis system repair guide completely to understand what is required to do the repair. If you feel like you need help with this project, we are just one call away. 

A reverse osmosis system can deliver water at an unparalleled level of purity, but they are also known to develop some common problems that require reverse osmosis system repair. You need to take care of these problems as soon as possible or you risk a chance to damaging your RO system. Thankfully you started reading our reverse osmosis system repair guide.

With the help of our reverse osmosis system repair guide, you will have all the resources you need for a trouble-free reverse osmosis system repair. As a result, you will not have to hire a plumber to do it for you.

Table Of Contents:

My RO System Is Not Working. Do I Need Reverse Osmosis System Repair?

If your reverse osmosis system is not working correctly there could be any number of things that are causing this.

To successfully troubleshoot your reverse osmosis system, you should identify the root of the problem. The various parts of an RO system work together to provide you with clean and pure water. One problem could be caused by multiple RO components malfunctioning, so troubleshooting your reverse osmosis system requires a systematic approach to eliminate possible issues.

Luckily for you that I have created this guide!

Below you will find our Reverse Osmosis System Repair Guide. Please keep in mind that the solutions offered are given as a general guideline, so we strongly recommend that you consult your specific RO systems' owner's manual or contact us today.

Preparations For The Reverse Osmosis System Repair

Before tackling the reverse osmosis system repair, you need to know the key components of your RO system are.

  • Filters: Prefilters provide sediment and chlorine protection. Sediment in your water can damage or clog the flow restrictor. Chlorine can also destroy the RO membrane material by oxidation. Post filters provide a fresh pass through carbon before making its way to your RO faucet, ice maker, or refrigerator.

  • Membrane: The Ro membrane operates on pressure. The pressure is the driving force that pushes water through the system. Without enough pressure, water production and TDS rejection will be negligible. Production rates vary and are based on feed pressure and water temperature.

  • Flow Restrictor: The flow restrictor provides resistance to create a driving force on the RO membrane while efficiently metering water flow rate to the drain. 

  • Check Valve: The check valve protects the RO membrane from backpressure and allows pressure to build up with a full tank, thus activating the ASO valve. Without it, the reverse osmosis system will not shut down and could potentially cause membrane failure due to backflow.

  • Automatic Shutt-Off Valve (ASO): This device monitors the feed and tank pressures. When the storage tank pressure reaches 2/3 of line pressure, the ASO valve hydraulically closes, stopping all water flow.

  • Storage Tank: Pressure tank (hydro-pneumatic) is the term used for the style of storage tanks that are used with today's reverse osmosis systems and the tanks are divided into two chambers, one for water and the other one is for air. As the tank fills with water, the separating diaphragm expands into the air chamber and increases the pressure on that side. This pressure pushes the water back out of the tank to the RO faucet. The loss of pre-charge air pressure or diaphragm integrity can cause little or no water flow at the RO faucet.

  • Drain Saddle: RO systems have a drain line that flows to the drain carrying the contaminants away. The waterline from the air gap faucet connects to the sink drain line with a drain saddle.

  • Air Gap: Plumbing codes require any cross-connection (feed supply on one side, drain connection on the other) to have a backflow prevention device. This prevents drain or sewage water from backing up into your drinking water supply.

  • Feed Pressure: The water pressure entering the RO system is crucial to the system's performance, so it is important to consider the impact of high levels of TDS and low pressure can have on your RO system's performance.

Reverse Osmosis System Repair 101

How Does Reverse Osmosis Work? Reverse osmosis works as water is forced across a semi-permeable membrane, leaving the contaminants behind to be flushed down the drain, and the clean water is collected in a storage tank for later use.

Now that you know how reverse osmosis works it's time to learn how to repair the system.

It's time to learn how you can repair your reverse osmosis system the correct way. With a little preparation and the necessary tools, you don't have to hire a professional plumber to fix it the right way.

Do I need a plumber to help me out?


Typically, it is really simple to troubleshoot the most common problems that people have with their RO system. Below you will find a step-by-step guide that will show you how you can repair your RO system.

Slow Water Flow From Faucet

You wake up and go to the kitchen to get a glass of water. As the glass starts to fill you notice that the water pressure is down to a trickle. Little to no water coming from your faucet indicates that you have either low volume or low pressure.

filling up a glass of water

A malfunctioning storage tank may be to blame. Inside the storage tank is an air bladder, so when water flows into it, it causes the pressure to increase. If the bladder leaks or breaks, it cannot build up enough pressure. This causes the water not to be delivered to the faucet in the volume that you are used to.

To solve this, you need to lift the tank to see if it's full of water. A full tank will weigh about 20 pounds where an empty tank will weigh about a pound or two. If the tank feels heavy then there is a problem inside of the storage tank.

Are You Ready To Have Filtered Water? Let's Get Started!


Pressurize RO Tank

Here is what you need to do.

  • 1. Shut off the cold water supply to the RO system

  • 2. Close the storage tank valve

  • 3. Disconnect the tank from the system and take it outside. Open the tank valve to drain out the water. The flow of water will decrease as the water is poured out.

  • 4. Since there is a lot of water still in the storage tank, you need to pump air into the tank's pressure vessel using a bike pump or a compressor. With each pump, more water will pour out

  • 5. Once the tank is empty, check the pressure inside with a pressure gauge. You should have a reading of 6-8 psi. If it is below that you need to keep pumping more air into it.

  • 6. Reconnect the tank to your RO system and open up the tank valve and the feed water valve. Let the system refill.

If the problem continues then that's a sign that the bladder inside of the tank is damaged and it needs to be replaced.

water dripping from a faucet

Slow faucet water flow can also mean that you have low feed water pressure (below 40 psi). If this is the case for you then a booster pump is your best option, but there a couple of other reasons that can cause the issue.

  • Clogged filters/RO membrane - The RO membrane can clog when the membrane has to process exceptionally hard water. You can either replace your systems' RO membrane more often or you can install a water softener in your home. The water softener will remove the hardness minerals from the water before the water reaches your RO system. Your RO filters will need to be replaced if they are clogged.

  • Bent Tubing - Bent tubing can reduce the pressure which in turn causes low water flow, so you should check the tubing and straighten all water lines that were bent.

Water Running Continuously Down the Drain

All RO systems work on pressure. When the storage tank is full and at full pressure, it triggers the automatic shut-off valve to close. This stops more water from flowing into the system. It also stops more rejected water flowing down the drain line.

Water will continuously flow down the drain line if the shut-off valve or check valve is broken.

So what do I do?

You need to measure the pressure in the storage tank with a pressure gauge when the tank is full. You know if the tank is full by lifting it up. It should be heavy. The pressure needs to be 35-40 psi. If it is, then either your shut-off valve or check valve is most likely defected and needs to be replaced.

Testing the Valves: Test #1



    Draw about 20 ounces of water from the RO faucet to drop the pressure in the storage tank so your RO system will start processing more water.


    Close the storage tanks' valve to simulate a full tank.


    Wait for 5 minutes.


    Check to see if water has stopped flowing down the drain line by either listening closely or by pulling out the drain line from the drain saddle. If so, both valves are working perfectly. However, if water does continue to flow down the drain, you either have a bad automatic shut-off valve or a check valve. In that case, continue with test #2.

Testing the Valves: Test #2


  • Let the tank refill and keep the tank valve open.

  • Turn off the feed water valve.

  • Check to see if the water is still flowing down the drain line by either listening closely or by pulling out the drain line from the drain saddle. If water is coming out of the storage tank, this means that the check valve is broken and needs to be replaced. When no water is flowing, the system's automatic shut-off valve is broken and needs to be replaced.

Other common causes for water running continuously down the drain line of your RO system include:


    Feedwater pressure is below 40 psi. If this is the case you then you need to add a pressure pump.


    Your system wasn't properly installed and it's likely that the RO membrane causes the overflow, so take great care to fit all system parts in their correct positions.


    Your RO system may not ever stop running if the flow restrictor inside the drain line is worn out, so replace the restrictor.

Reverse Osmosis System Repair: Air Gap Leaking

If you have water coming out of the air gap then you are experiencing a very common problem called an 'air gap leak'. This usually happens when food and other debris accumulate in the drain.

illustration of a sinks air gap


The purpose of an air gap is to assure that drain water cannot flow back into you your RO system. In normal operations, water runs from the storage tank to the faucet and falls through a small pocket of air called an 'air gap'. When the drain line starts to clog up, it creates pressure, which causes water to flow out of the faucet and onto your sink.

All you have to do to fix this is clear out the drain line so the water can flow freely again. Use a pipe cleaner or wire to clean the end of the drain line that is connected to the drain saddle and clean the drain saddle itself. Drain saddles tend to move around so the holes may not be lined up. So make sure to align the drain saddle with the drain line hole.

How Can You Prevent An Air Gap Leak?

You cannot completely eliminate the chances for an air gap leak, but you can take the necessary precautions that reduce the frequency in which an air gap leak occurs.


    First of all, avoid rinsing large chunks of food or other stuff down the drain


    Regularly treat your drain line with a natural cleaner to dissolve possible blockages

Dripping or Leaking Faucet

If you have a leaking faucet then that indicates that one or more water filtration system parts are loosely fitted. To stop the leaking, you need to thoroughly tighten all fittings. Push the tubing further into their ports, valves, and drain saddle. If the leaking originates from the bottom of the faucet stem, then you are out of luck. You need to replace the part.

Bad Taste and Odors

filter change schedule

If you didn't buy a high-quality RO system then you may be noticing that your water doesn't taste as high quality as you thought. The only way to prevent this from happening is to invest your money into a decent system that is up to date to today's standards.

After years of service, your RO system may have developed a biofilm accumulation in the system's filter stages. At this point, you should replace any clogged filters or fouled RO membrane immediately. You should replace these components on a regular basis (once a year). If you let germs accumulate in your RO system, it can cause a serious threat to your health.

We recommend you maintain your RO system periodically and to clean it according to the manufacturer's instructions. This includes sanitizing the storage tank.

Unused Water

Over time bacteria will start to grow in stagnant water. This could be the cause of bad taste and smell. If you have not used your RO system in a while, then it's a good idea to flush the system a few times before you restart using the water again.

old clock

Noisy Air Gap Faucet or Drain

When you first turn on your RO system, or you recently replaced one or more of the filter cartridges, the drain line may make some noise. There is nothing to worry about. The sound is caused by air being pushed out of the system. This issue will not last more than a few days to a week.

If the noise hasn't stopped by then and it bothers you, make sure that all of the tubings are set straight. The noise can also be caused by a restriction in the drain tube or drain saddle. Check to make sure the problem doesn't originate from there.

If that didn't help, then it's time to check the entire system for gaps and correct any problems.

Leaking Filter or Membrane Housing

A worn-out O-ring in one of your RO system's filter housing may be causing the leak. Below you will find the steps to solve this issue.

  • Close the water feed valve so no more water can enter the system.

  • Close the water storage tank valve.

  • Unscrew the leaking filter housing.

  • Replace the worn-out O-ring.

  • You need to double-check and make sure the O-ring is placed correctly.

  • Screw the filter housing back onto the RO module and hand tighten it. Next, use your housing wrench to carefully tighten the housing a little bit more.

  • Open up the storage tank and feed water valves.

  • Inspect the system for leaks. Damaged filter housing needs to be replaced.

  • Pro Tip: You can check if the housing is causing the problem by exchanging it with one of the system's other filters.

It is also common for a housing cap to become loose over time causing the O-ring to be displaced. 

Therefore, you should tighten the housing cap up periodically.

The Water Filter One Difference

If your RO faucet has a low volume of water coming out of it or you think you are in need of our reverse osmosis system repair service, call us today so we can troubleshoot your reverse osmosis system to see what kind of repair you are in need of.

Repairs can range from pressurizing your RO tank to replacing valves within the RO system. Call Water Filter One today to get your reverse osmosis system back in working order.


With a little preparation and the necessary tools, you don't have to hire a professional plumber to fix your reverse osmosis system the right way.

Typically, it is really simple to troubleshoot the most common problems that people have with their RO system. Our step-by-step Water Purification guide will show you how you can repair your RO system.

Thank you for reading our reverse osmosis system repair guide and good luck repairing your water filtration system.

Are You Ready To Have Filtered Water? Let's Get Started!


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