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Does a Dishwasher Need a Check Valve? (Answered)

If you have installed the dishwasher in your kitchen, you must know that you will need some appliances. You cannot only run the dishwasher and clean everything.

Your utensils and other kitchen appliances must come with the safe dishwasher certification; otherwise, they will get stained and damaged.

Also, your dishwasher needs to be set with all the required instruments to clean your appliances. If you don’t have any concerns regarding the dishwasher instruments, you will fail to use them for a long time.

What is a dishwasher check valve?

A dishwasher check valve is a backflow preventer tool. The check valves are used in a place where the black flow of water can cause harm because the polluted water contains germs for diseases.

A dishwasher check valve is a tool built based on pressure difference, installed on the cross-connection of good and bad water.

The check valve ensures a one-way water flow, meaning it will never allow the polluted water to push back to the dishwasher. In a sense, you even term it hygiene ensures for the machine.

Does a dishwasher need a check valve?

A Dishwasher needs a check valve. A one-way valve attached to the drain hose and drain line makes up a dishwasher’s check valve. It works like the safety feature of your dishwasher that you cannot ignore. So, it’s not recommended to run the dishwasher without a check valve.

When the water is draining, it prevents dirty water, food, and any other type of backflow from entering the dishwasher again. The part of the dishwasher is in charge of ensuring that water does not get back into the machine.

Interestingly, you can run your dishwasher without using a check valve. It’s not the essential component that will help to run the dishwasher. But it’s not recommended to run the dishwasher without using the check valve.

If you want to know why the dishwasher needs a check valve, you should know the reasons below. I will talk about two crucial importance of using a check valve for your dishwasher.

Prevent Contamination:

Since backflow can transfer old food, dirty soapy water, and other impurities into your dishwasher, which can re-dirty your dishes and pose a health risk due to bacteria in the drain lines, check valves are essential.

Control Flow Direction:

Check valves are intended to prohibit water from flowing in one direction while allowing water to move in the opposite direction with some degree of freedom.

In yet another type of check valve, the pressure of the fluid flow is used to compress a spring-loaded disc located in the liquid flow.

Additionally, it permits the passage of a medium in only one direction. When pressure conditions could ordinarily force the flow of a medium through a pipe to go in the other direction, a non-return valve is installed so that the flow goes in the right direction instead.

That is why every dishwasher requires a check valve. Although it’s not mandatory to have check valves installed in your dishwasher, you must have it on your urge.

Do all dishwashers have check valves?

Almost all the brand’s dishwashers have check valves in them. Check valve job is stopping the polluted water from coming back into the dishwasher. Air gaps are the divider between fresh and polluted water, called the cross-connection point.

Air gaps can prevent water reverse flow, but they also provide the check valves for better safety. Some old versions may lack the facility of check valves.

Having a check valve installed in your dishwasher ensures you double safety from food and bad water coming back to your dishwasher, which can cause your health risks.

Can I use a dishwasher without check valve?

You can use a dishwasher without a check valve. Check valve duty is to prevent bad water and stuff reverse flow. The old installation techniques, like making a high loop on the drain line, can prevent the backflow. It is more effective when the sink contains some space.

Then all the dishwashers have air gaps installed in them, which is the divider between polluted water and regular water. The air gaps work as a wall of protection from bad water backflow. So your dishwasher can be used even if it doesn’t have a check valve.

What does a dishwasher check valve do and how does it work?

The dishwasher check valve stops the water backflow with the help of a pressure mechanism. The check valve consists of two-port ports, one for the inflow of water and another for the outflow of things.

The interchangeable name of one-way valve is also given for the reason as it only allows the water to flow in one direction.

The working mechanism of check valves is based on the pressure difference. The higher pressure from the side that will drain the bad water opens the inflow port. This pressure causes the lousy water to drain through the check valve’s outflow port.

When the pressure from the inflow side decreases compared to the outflow port, bad water is trying to push back to your dishwasher.

The check valve flapper installed in a Hinch closes instantly. The outflow port gets sealed up due to the changing side of pressure and protects the dishwasher from the reverse flow of bad water.

Valves are primarily designed similarly to a rat that can push into a rat trap door, but it can never open it from inside the trap by pushing it from the opposite direction.

As the backflow is sealed, the dishwasher check valves ensure excellent safety from many diseases. If the food and polluted water drained through the dishwasher comes back to it, it will be full of bacteria.

It is harmful washing your dish in that bacteria-affected one. Check valves installed on the dishwasher ensure better safety against this

health risk. So the summary would be that a dishwasher check valve’s job is to stop lousy water from coming back towards the dishwasher, which operates based on a pressure difference mechanism.

Does a dishwasher need a double check valve or a single check valve?

A dishwasher needs a double check valve. Also, if you want, you may use a single check valve on your dishwasher because there is no specific instruction on which type of check valve you must use.

To maintain the high level of cleanliness and safety of the water supply, a dishwasher with a higher risk of backflow is recommended to be equipped with a double check valve.

This type of valve has two internal valves that fight against potential risks and protect your dishes and your dishwasher. Even if one of the valves fails, the other valves should be able to keep backflow and contaminants from entering the primary water supply.

The double-check valve assembly is excellent for preventing back pressure and back-siphonage from occurring.  It is not the same as the two-way check valves, which are sometimes incorrectly referred to as double check valves, that are utilized in the air brake systems of heavy trucks. Those check valves select from the source with the highest pressure.

Where is the check valve on a dishwasher?

A check valve will be installed in the drain outlet of some dishwasher models. It is designed to flow water in only one direction, but it will stop soiled water from flowing back into the dishwasher if properly adjusted and used.


At the outlet, close to the drain hose, is where you’ll find the check valve in Kenmore. If the check valve on your Kenmore dishwasher gets stuck in the close position, water will not be able to drain out of the appliance.


Most Bosch dishwashers will have the check valve situated close to the drain pump.


You’ll find the check valve in your Whirlpool dishwasher under the dishwasher, just in front of where the drain hose connects.

Because it is a one-way valve, it allows water to drain from the dishwasher but prevents it from flowing back into it.


The check valve in the Kitchenaid dishwasher consists of a small rubber flapper and can be found inside the hose just before the 90-degree elbow at the bottom of the sump or pump. This is the location where the drain hose connects.


Check valve can be found on the outlet port of the drain pump or the appliance’s housing in the Frigidaire models. If you want to check it all by yourself, you need to take off the lower access panel or the kickplate first. 

Final thought

Although you can run the dishwasher without using a check valve, it’s not recommended to avoid it. It will work as the safest feature of your dishwasher that will work to ensure safety. Therefore, a dishwasher must need a check valve to work safely. So, provide the check valve, then run it.