RO Solenoid Valve – What is it and When to Change?

Solenoid valves are used in both home appliances and small or large industrial applications.

In short, solenoid valves are used wherever there is a need to automatically control the flow of liquid or gas.

For the purpose of this post, we will concentrate only on solenoid valves used in electrical water purifiers.

A Solenoid Valve in a water purifier is an electromechanically operated valve that is used to control the flow of input water.

It allows the input water to enter the water purifier only when the machine is turned on. When the machine is turned off, the solenoid valve will automatically shut off the flow of water.

The main function of the solenoid valve in a water purifier is to avoid water overflow.

A Typical Solenoid Valve

Solenoid valves are used in both RO water purifiers and UV water purifiers.

In an RO water purifier, a solenoid valve is generally installed after a sediment filter or pre-carbon filter and before the RO membrane.

Solenoid valves come in different ratings like 24V, 36V, 48V, etc.

Solenoid valves come in both AC and DC power. If your water purifier has a DC adapter or SMPS, choose a DC solenoid valve. If there is no DC adapter or SMPS, choose an AC solenoid valve.

Most branded water purifiers in India come with a DC adapter so you don’t need to worry as DC solenoid valves are the default choice.

Like water purifiers, solenoid valves are also used in washing machines to turn on or off the flow of input water.

How Do RO Solenoid Valves Work?

A solenoid valve features a solenoid, which is an electric coil with a movable ferromagnetic core (plunger) in its center.

Parts of a Solenoid Valve (Image Courtesy: SafeRack)

When you turn on your purifier, an electric current passes through the coil. This creates a magnetic field. This magnetic field exerts an upward force on the plunger. This force pulls up the plunger and opens the flow of water.

Solenoid Valves Working

When you turn off the purifier, the plunger returns back to its original position and closes off the flow of water.

This is the basic science behind the functioning of a solenoid valve.

When to Change RO Solenoid Valve?

You need to change the solenoid valve of your RO purifier when any of the two conditions given below is true.

  • When the RO machine is turned on, input water is normal but there is no output from the solenoid valve.
  • When the RO machine is turned off, there is a continuous flow of output water from the solenoid valve.
Pro Tip
Before changing, remove the solenoid valve from the RO assembly. Now open one end (opposite to the magnet) of the solenoid valve by unscrewing it. Take out all the parts like the piston, spring, and rubber valve. Clean them all thoroughly.

After cleaning, re-assemble all the parts and fit the solenoid valve back in the RO assembly.

Now check if the solenoid valve is working fine or not.

If it works fine, no need to change the solenoid valve. If it doesn’t, install a new RO solenoid valve.

Things to Keep in Mind When Buying/Replacing a Solenoid Valve?

  • When replacing the RO solenoid valve, always remember that the rating of the solenoid valve and that of RO’s power supply (SMPS) and the RO pump should be the same. E.g. for a 36V power supply, a 36V solenoid valve should be used. If you do not match the rating of the solenoid valve with the power supply then the solenoid valve will get damaged instantly or after some time.
  • Never install the solenoid valve before the sediment filter. If you do, physical impurities in the water will choke the solenoid valve.

We hope the above information answers all your queries about the solenoid valve. If you have any queries or suggestions, please leave a comment below.

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Pramod

An engineering graduate from a top Indian university, boasts a decade-long expertise in reviewing home appliances, particularly water purifiers. As the Editor-in-Chief of BestROWaterPurifier.in, his insights empower readers with valuable advice for healthier choices in household essentials.

4 Comments
  1. Very useful information with basic technicalities. Diagram helps to understand the working pattern. Thanks.

  2. All informations that I need to know found here, thanks for you to upload significant and proper information in simple language. please keep it up.

  3. Very Good Info.
    Well explained.
    Thank you.

  4. Reply
    Subramani Ranganathan November 27, 2022 at 10:47 pm

    Very useful information.
    All information required are found in one place.
    Well explained. Even a layman can understand.

    I appreciate the time and effort you have taken to upload this information. I wish you well.

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