Why Your Reverse Osmosis System Is Leaking – How To Fix It

Many Americans rely on reverse osmosis systems to provide clean water for themselves and their families. However, overtime an RO water system can develop issues, such as leakages, and require troubleshooting and maintenance.

Reverse osmosis systems leak when there is an air gap in the faucet or filter housing. Improper installation, blockage, pressure issues, and loosely connected parts can also cause an RO system to leak. Less common reasons include O-ring-related issues or overtightened filter house.

This article will take you through all the possible reasons why a reverse osmosis system may be leaking and provide step-by-step instructions on how to solve each problem.

Why is my reverse osmosis system leaking?

Many things can cause a Reverse Osmosis system to leak. From regular wear and tear, maintenance-related problems, installation issues, or technical faults.

Reverse osmosis system leaks typically occur in the following areas:

Water leaking from the air gap faucet

Reverse osmosis systems extract pollutants from water molecules before essentially flushing them down the drain. However, any technical issues or defects generate resistance, which causes the water to leak through an air gap hole instead. A leaking air gap can also reintroduce pollutants to the filtered water. 

The following issues lead to a leaking air gap, including;

1. Drain line issues.

A leaking air gap could also be the result of underlying drain line issues, such as a clogged drain line or loop/dip drain line tubing. The air gap leak, which occurs when water seeps through the hole on an air gap faucet, is a typical leaking problem in most RO systems. To know if there is an air gap leak, confirm if water is pouring out from the air gap hole at the base of the faucet.

Typically, an air gap is designed to prevent the backflow of water into the RO unit by directing the excess water into the drain lines.

However, when a large amount of debris builds up in the drain line, it clogs it, creating back pressure that causes water to flow out via the air gap. But because the air gap is designed to prevent backflow, it forces it to the faucet, and creates the leaking you are experiencing.

A looped or dipped drain line tubing can also cause an air gap leak by preventing water from flowing into the drain saddle. When this happens, the water pressure is likely to force water through the air gap to create the leak.


  • If you notice that your faucet is leaking due to clogged drain lines, just unplug the drain line and manually clear it before reconnecting.
  • If your RO system’s problem is loops or sharp dips, turn off the RO system, detach the drain line, and attempt straightening it out before reconnecting it for usage.
  • If you are unable to complete the task on your own, hire a professional plumber to come do it for you.
  • Check if there is any loose connection and fix it by tightening.
  • Replace the faucet if the problem is a damaged stem.
  • A displaced drain saddle can also cause a leaky faucet, so double-check and realign the drain saddle with the drain hole.

2. Improper installation of the air gap.

It is possible that an RO system’s air gap is leaking due to improper installation. The RO installation process can be done by the home owner or a professional. However, any slight mistake during installation or maintenance, will affect the performance of the RO.

When installing an RO’s air gap, place the drain saddle far from the disposal. This is because the disposal can blast debris into the drain pipe, blocking the air gap.

The drain saddle should also be prevented from rotating around the drilled hole that serves as an air gap during installation of the RO system’s faucet. 


  • Remove and reinstall the faucet and air gap to avoid leakage.
  • If it cannot be reinstalled, consider buying a replacement air gap.

Preventative measures.

  • Read and understand the full installation process before installing the RO system or hire a professional to help you.

3. Loosely connected parts.

One frequent reason for a leaking RO system faucet is loosely connected parts.

Components can also become loose after a long period of time, but it is more common in newly installed RO systems. Because RO systems require a high level of pressurization, any loose connecting fittings are prone to collapsing under the system’s pressure.

High pressure can loosen or break the connection fittings, with burst fittings the most common result of pressure damage. Otherwise, loose fittings tend to be the result of not properly tightening each component when cleaning the unit or replacing filters.

Fortunately, a loose connection can be easily identified because the water will seep from the region containing the component that requires tightening or reinstallation. The water can usually be seen and felt as droplets.


  • If you suspect a loose connection is causing the leak, first gain access to it, then detach and reinstall the connector fitting. Do not overtighten.
  • Replace any damaged or broken components.

4. Blockage.

A simple blockage can cause water to leak from your RO system’s air gap. An RO system can become blocked in the drain saddle, drain tube, drain pipe, and the air gap hole. Water leakages can occur when any of these become blocked.

Current feed water conditions are the likely culprit for blockages. The more pollutants and dissolved solids in the input water, the more debris will be collected. After a period of time, it becomes clogged, leading to water flow obstruction. When the water flow is obstructed, air gaps close again.

Debris may also collect in the air gap of your RO system due to a slow-running sink drain.


  • To prevent leakage in the air gap, unclog the drain line, and it will begin to flow normally. Use a pipe cleaner or wire brush to do so.
  • Schedule regular cleaning and maintenance of the RO, including the tanks, lines and filters.
  • Clean your RO system according to the user manual instructions.

5. High internal pressure or pressure spikes.

A common reason for water leaking from an RO system’s air gap faucet is pressure. This could be high internal pressure or pressure spikes.

Normally, RO systems use high pressure to remove contaminants from water. So, in case of pressure spikes from your water supply, which happens from time to time, the RO system becomes exposed to excessively high pressures.

Your Reverse Osmosis system’s tubings, drain lines, air bladder, and connectors can be damaged if there is a pressure spike.

Solutions to pressure spike on RO systems.

  • Replace any damaged components.
  • Consider purchasing a pressure regulator.

6. General wear and tear.

The age of the RO system, resulting in normal wear and tear, can lead to the system leaking over time. Typically, an RO system can last from anywhere between 8 years to 10 years. But, like any other equipment, RO systems get old and worn out with time.

These leaks may be a reminder for you to start thinking about replacing your entire RO system with a new one rather than the normal replacement of filters, O-rings, and filter housings.

How to know you need a new RO system

  • Frequent technical issues and more damages than normal.
  • The system has become louder than usual.
  • Bad tasting water even after changing filters.
  • If you have been using an RO system for more than 10 years.


  • Replace a reverse osmosis system after the specified amount of time by the manufacturer.

How to prevent an air gap leak.

  • Use an all-natural drain cleaner to keep organic waste from building up in your drain.
  • Avoid rinsing big particles that can clog the drain line.

Leaking Filter Housing

Reverse osmosis systems have filters which are placed in the filter housing. Over time, it can start leaking because of the following reasons:

1. O-ring-related problems.

A reverse osmosis filter housing is usually leaking because of O-ring-related issues. An O-Ring is a little rubber ring used to provide an airtight seal between interlocking components.  Typically black in color.

Almost all water filtration and other plumbing appliances, as well as reverse osmosis systems, use O-rings.

If an O-ring has any faults in it, or even some dust or dirt on it, it will form a leak. If you frequently service your reverse osmosis water system (as you should) and interact with the connection, twisted, pushed out of place, or damaged O-Rings are a common problem.

If the O-Ring is not damaged, the rubber band may usually be simply pushed back into place so that it fits snugly around the housing entry. If the O-Ring in your older RO water system has snapped or is otherwise damaged, you can usually get a replacement O-ring from Amazon that fits your model.

Water can also leak from the seal between the housing and the connecting tubes if an O-Ring is damaged or twisted.

Some reverse osmosis systems, like Waterdrop, can leak in the filter housing because the filters are not correctly installed. APEC reverse osmosis systems also have specific leakage issues.

Water Purification Guide has a complete troubleshooting guide for leaking APEC reverse osmosis systems available here.

Issues to do with O-rings include:

  • Not in place.
  • Broken.
  • Faulty or loose.
  • Dirty

Solutions to leaking filter housing in RO systems.

  • If you use a Waterdrop RO system, check if the filters are correctly installed.
  • If your RO system has O-rings at the filter housing, take for example, APEC; inspect the O-rings thoroughly to see if they are misplaced, stretched, or broken.

How to inspect an RO system filter housing O-rings condition.

  • To prevent more water from entering the system, close the feed valve.
  • Close the valve on the RO tank.
  • Then, gently detach the filter housing to inspect the O-rings for damage and proper positioning.
  • Before screwing back the case, make sure the O-rings are securely in place.
  • Close the feed water valve and reassemble the housing.
  • If the leak persists despite the replacement of the O-rings, the casing may be damaged. To stop the leak, replace the casing.
  • For other RO systems like Waterdrop, remove the filters and reinstall them correctly and securely to stop the leak.

2. Overtightening.

One reason there is a leak at the filter housing could be because it is overtightened. Most manufacturers clearly state in their user manual handbooks that filter housings should not be overtightened. This is usually to avoid water leakage.

Many new reverse osmosis users think that if you tighten the filter housing, it will prevent leaks, but in fact the opposite is the case. If you overtighten the housings, it can crack, or the O-ring inside will flatten, enabling water to pass through.


  • Little droplets of water flowing from the filter housing’s top.


  • Turn off the water inlet to the filter and that coming out of a filter.
  • Disconnect the faucet and hose if you can’t easily remove the filter housing from its current location.
  • Position the housing on a level surface.
  • Then, hold the mounting bracket with one hand and with the other, detach the filter housing with a wrench.
  • Replace the filter housing with a new one.

Related Questions

Why is my reverse osmosis system constantly draining?

A reverse osmosis system constantly drains because of low pressure from the feed water. The membrane filter requiring replacement because it is worn out, or a faulty check valve or ASO valve (Automatic Shut-Off valve) can also lead to continual draining.

Why does my reverse osmosis faucet leak?

A reverse osmosis faucet may leak because of a constraint preventing water from going to the drain or a faulty installation. However, most RO faucet leaks are actually from the air gap, which is often the result of pressure issues.

See the top of this article for a complete troubleshooting guide on leaking reverse osmosis systems.

The Best Reverse Osmosis Systems We’ve Reviewed

Crystal Quest | 3000C Reverse Osmosis System

These are truly reliable RO systems that are made in the U.S. They use a 13-stage reverse osmosis system to remove 99.9% of contaminants, including iron, volatile organic carbon compounds (VOCs), insecticides, pesticides, bacteria, viruses, parasites, protozoa, pyrogens, and industrial solvents. Get the 3000C on CrystalQuest.com.

Pentair | FreshPoint 5-Stage Reverse Osmosis System

These systems are compact and very simple to install. Using a 5-stage filter system, they are effective at removing 99% of contaminants from regular tap water. They can be purchased as a basic model (GRO-575B) or a monitored model (GRO-575M), which alerts you when it’s time to change the membrane. Both will produce 1-part pure water to 2.5-parts wastewater – which is excellent! Check them out here at Pentair.com.

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