Why Is My Reverse Osmosis System Making Noise? (+ How to Fix)
Written by: Gene Fitzgerald // Last Updated: May 31, 2023
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Reverse osmosis systems can make noise for a variety of reasons, including both normal filtration sounds and abnormal issues.
If your RO system is making noise, you’ll need to perform a little troubleshooting to determine the cause.
Once you’ve narrowed down the cause of your problem, we’ll explain how to fix the issue and get your system back to normal.
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Key Takeaways
- Reverse osmosis systems make noise for several reasons, some of which are normal while others are indicative of underlying issues.
- If your system is making noise, you’ll need to narrow down the cause before you can fix the issue. Slight humming after dispensing water or light gurgling from the air gap faucet are normal noises. Loud gurgling or hissing is indicative of a problem and so can be clicking, whining, and sputtering.
- Some of the issues that might be causing your noise problem are a misaligned or cracked drain line, a constantly draining system, high feed water pressure, trapped air bubbles, excessive tubing length, an oversized RO membrane, or leaks.
Reasons Why Your Reverse Osmosis System Is Making Noise
So, why is your RO system making noise?
Reverse osmosis systems make noise as a normal part of the water filtration process.
However, they shouldn’t be making noise 24/7, and if your system starts making an unusual noise out of the blue, you can be fairly confident there is a problem.
Normal Noise Produced by Reverse Osmosis
RO systems will make slight noises as they process water, even when the faucet is turned off.
When you turn the faucet on, you may notice a slight humming noise as the system starts filtering more water. Additionally, a minor gurgling noise from the faucet is normal as wastewater flows past the air gap in the faucet and down the drain line.
If you’re running an RO system for the first time, you might hear a whining noise when the tank pressurizes. You may also notice gurgling from the air gap faucet as it releases air.
All of that is perfectly normal.
Abnormal Noise Produced by RO
Abnormal noise produced by reverse osmosis systems is generally louder than normal filtration noise. One sure sign of a problem somewhere in your system is loud gurgling, with hissing from the RO faucet being another.
How to Deal with Reverse Osmosis Noise
If you suspect your RO system is making an abnormal noise, the following guide should help you troubleshoot the problem.
(Continuous) Siphoning Noise in Sink Drain
Hearing a draining noise coming from the system is normal while the tank fills, but if you hear it 24/7, there is definitely an underlying problem. An unusually loud draining noise is a further indication that something is wrong with your system.
Misaligned Drain Line
If the draining noise is unusually loud and becomes more of a hissing noise, you may have a misaligned drain line. The drain line runs from the RO membrane outlet to the drain saddle – which is where the drain line connects with the drain pipe under your sink.
Over time the drain saddle can come loose, which can partially block or pinch the drain line – similar to putting your thumb over the end of a garden hose.
To fix this, you’ll need to shut off the feed water valve, allow the drain line to empty, and then unscrew the drain saddle. Next, check if any debris is lodged in your drain line, and then realign the drain saddle with the drain pipe before fastening it in place.
RO System Is Draining Constantly
A constantly draining RO system is indicative of a problem somewhere in the unit. This can have several causes including low feed water pressure, a clogged membrane, an underpressurized storage tank, or a broken ASO Valve/Check Valve/Flow restrictor.
Hissing Faucet Noise
If the noise coming from your faucet’s air gap isn’t the regular gurgling noise, but rather a hissing, there are several possible causes.
Obstruction in Faucet Drain Line
A buildup of debris in the drain line can cause a whistling from your air gap faucet. To fix this, disconnect the drain line running to the faucet, examine it for debris, and dislodge any clogged dirt or debris.
Cracks in the Tubing
Cracks in the tubing running to and from the faucet can also cause a loud hissing noise.
To fix this, examine the condition of the tubing connection ends. If you spot any cracks, remove that section, cut off the damaged end, and then reconnect the tubing to the faucet.
Feed Water Pressure Too High
While low feed water pressure is a more common issue, high feed water pressure comes with its own issues. High feed water pressure can cause your faucet’s air gap to pull in a large amount of air – leading to hissing noises.
To fix this you will need to install a pressure-reducing valve to regulate the pressure.
System Leakage
If none of the above issues are causing the hissing noise, examine your system for leaks and fix them should you find any. Leaks in your system will cause the RO faucet to draw in excess air – leading to hissing.
Vibrating and Clicking Sounds
Clicking noises can be caused by sections of tubing suddenly coming under pressure when water flows through them. If the tubing section is longer than necessary, it can knock against the cabinet or tank, causing a clicking noise.
To fix this issue, simply shorten the length of the tubing using tubing cutters or a sharp utility knife.
Vibrating noises can be caused by trapped air bubbles inside the system. To remove these trapped air bubbles, follow the steps outlined below:
- Shut off the ball valve on top of the storage tank.
- Tilt the RO system at a 45-degree angle with only the first pre-filter touching the ground. This will help to dissipate the accumulated bubbles.
- With the system tilted, turn on the RO faucet and let the water run for 1 minute, then shut off the faucet.
- Wait 20 to 30 seconds and repeat the previous step 3 to 4 times.
Gurgling & Sputtering
If you have gurgling and sputtering coming from your RO faucet, there are several possible causes.
Air Bubbles Have Accumulated Inside the System
Air bubbles can cause gurgling noises in addition to vibrating noises. To fix this issue, simply follow the steps outlined above.
Siphoning Issues
If the section of tubing running from the faucet to the drain saddle is too long, it can cause siphoning issues. This means air will fill in the dip where the drain line sags – causing a gurgling noise.
The solution to this is simply shortening the length of tubing so there is no dip.
Oversized RO Membrane
If your reverse osmosis membrane is oversized compared to the rest of your system, your drain line will receive a higher flow rate than it can handle. This can cause a gurgling noise. Downsizing your membrane so it’s compatible with the rest of your system will solve this issue.
Further Reading:
Whining
If you notice whining coming from the system, it can either indicate a change in pressure after water leaves the storage tank or excessively high feed water pressure.
Feed Water Pressure Too High
If your feed water pressure is too high, water entering the reverse osmosis filter system can make a whining noise – in addition to being hard on filters and plumbing. Fixing this issue is simple – you will need to install a pressure-reducing valve to lower the water pressure before it enters the filter.
Pressure Changes
A change in system pressure takes place when you open the RO faucet and partially empty the storage tank. This can make a whining noise – which is completely normal – and will stop once the pressure stabilizes.
If you have any questions about reverse osmosis noise please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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