Reverse Osmosis System Making Loud Noise – What to Do

Reverse Osmosis System Making Loud Noise - What to Do

Most of the subtle noises that your Reverse Osmosis (RO) filtration system makes are common or normal. However, if your RO system is making louder than normal noises, it is likely that something is wrong with it, and the system should be inspected immediately.

A reverse osmosis system makes loud noises due to the following common reasons; improper installation, missing filters, missing membrane, changes in water pressure, trapped air bubbles, an overworked water pump, or an off-center drain line.

Reading the reasons above you might be wondering, “What does all of this mean?”. Well, to get the answer to that and a lot more you have come to the right place. We will explain all possible reasons why your RO is making loud noises and explore the solutions available to fix the problem. Read on!

Read my comprehensive article about reverse osmosis.

Loud Noises from My Reverse Osmosis – Is It Normal?

There are several reasons why an RO system will make loud noises. On most occasions, the problem is often small and can be easily fixed or figured out on your own.

Let’s begin by looking at the table below. This table should clear up any doubts that you may have regarding whether the noise you are hearing is normal or abnormal.


Normal Noises Produced by RO Abnormal Loud Noises Produced by RO
1. Humming noise from the unit as water is dispensed 1. Loud whining noises caused by a missing filter
2. A slight noise as water is processed for impurities 2. Loud whining noise caused by a missing membrane
3. A very slight gurgling or dripping sound coming from the sink drain 3. A drain line adapter that is out of alignment will make a loud noise
4. A low whining sound after initial installation 4. Sputtering noises as air bubbles accumulate inside the system over time
5. Pulsing or vibrating sound after changing filters or doing service work 5. Loud whining noises as a result of changing water pressure
6. Constant dripping or dribbling sounds from the drain
7. Loud mechanical noises from the water pump


The next step is to closely listen in order to decipher what type of sound you are hearing and where it is coming from. Pinpointing the source of the sound will often lead you to the problem at hand.

Getting Rid of Loud Noises in Reverse Osmosis Filtration Systems

Here are some of the most common sources of loud noises that you may hear if you own a reverse osmosis filtration system and how to get rid of them.

1. Noises caused due to changes in water pressure

Any time there is a change in water pressure you are likely to hear a soft whining noise from your RO unit. This sound is normal and will only last a few seconds; stopping as soon as the pressure has stabilized.

However, if the water pressure is too high, it can cause your RO unit to continually discharge excess water down the drain while also putting strain on your residential plumbing resulting in all sorts of abnormal noises.

The easiest solution to this problem is to add a pressure-reducing valve at the point where the public water supply enters your residential piping.

In cases of low water pressure or unstable water pressure, your RO system is likely to start and stop repeatedly. This will result in loud noises as the machine isn’t getting enough water causing air to build up.

In such an instance, you should always wait until the pressure in the system has normalized before using the purifier.

2. An off-center drain line

If you have located the source of a loud hissing noise (like a gas leak) to be coming from your sink drain, it is likely that the drain line isn’t centered or is misaligned.

If this is the case, check to see if any debris has clogged up the drain hole. If the drain hole is clear of debris, check if the drain saddle (a clamp that holds the drain line in place) is correctly aligned.

Simply tighten the drain saddle and make sure it is properly centered. This should get rid of the hissing noise you hear when wastewater is being discharged.

3. Auto shut off (ASO) valve malfunction

If the noise, you are hearing is that of constantly dripping water from the drain, this is an indication that your auto shut-off valve isn’t working.

The auto shut-off valve tells your RO system when to stop filtering water when the tank is full.

If the valve malfunctions, this never happens, which means your RO unit is constantly filtering water and discharging wastewater down the drain.

This will not only result in a loud continuous noise but also water wastage.

The only fix is to replace the ASO valve right away!

You can also make sure that this is indeed the problem by checking the PSI of your main tank using a pressure gauge.

If the reading is between 35-40 PSI and the RO unit is still working, you can be certain that your ASO valve isn’t working.

4. Missing or improper installation of filters & membrane

This is self-explanatory. Not having a membrane or filter will cause your RO unit to make weird noises.

Always make sure that the membrane and filters are installed correctly after doing any sanitization or maintenance work on your RO unit.

5. Other common faults

If you hear a loud mechanical sound coming from your water pump, get a professional to take a look at it.

If you hear loud rattling noises from your RO unit this can be an indication that your plumbing isn’t secure and most likely requires replacing.

Frequently Asked Questions

Q) How to get rid of sputtering noises from air bubbles?

Simply open your RO faucet and let all of the water in the tank flow out. This will remove any excess air from the system and stop the sputtering noise.

Q) When should I replace my RO membrane?

If you find that your RO system is no longer producing water, that the flow of water from your RO unit is less than it should be, or your RO system is constantly running, it is time to replace the membrane. Read my article about replacing your RO filter membrane.

Q) How often should an RO system be sanitized?

An RO system should be sanitized at least once a year. Filters should also be replaced every year. Read my article about sanitizing your RO system.

Final Thoughts

Your reverse osmosis unit can make loud noises due to the reasons mentioned above. In most instances, the noise can be eliminated with a quick fix. However, if you are having trouble determining the source of the loud noise, it is always recommended to call in a water treatment professional to correctly diagnose the issue and find an appropriate solution.

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children.

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