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Water Backing Up In Dishwasher When Not In Use

After the dishwashing cycle is complete, the water should be drained completely. But sometimes, you might see water backing up in the dishwasher when not in use. It can happen even when you have turned the dishwasher off. So, why is water backing up in dishwasher when not in use?

Water backs up in the dishwasher if the sink drain or the drain hose is clogged. If there is no P-trap in the sink drain, water can back up into the dishwasher as well. Faulty check valves or water inlet valves can also cause this problem.

We will focus on the main causes of the problem and find solutions that won’t cost you a fortune. Let’s get started.

Water Backing Up In Dishwasher: Main Reasons and Quick Fixes

Water Backing Up In Dishwasher

Check the following chart to get an idea of what you should do when water backs up into the dishwasher.

The drain hose is clogged or bentRemove food particles or other waste from the drain. Then, clean the sink drain with vinegar and baking soda
Garbage disposal cap isn’t removedTake out the garbage disposal and remove the cap from it. Then, install it again
Remove the drain hose from the assembly and use a plunger to unclog it. Check if the hose is bent somewhere
No P-trap is used in the drainInstall a P-trap to let wastewater pass easily
Faulty check valveLook out for damages or wear on the check valve. Replace it if necessary
Faulty water inlet valveCheck the water inlet valve for damage or burns. If it needs a replacement, call an experienced plumber

Many people often ask themselves, “Why does my dishwasher fill with water when it is not running?” We acknowledge the frustration and here are the right solutions for you.

1. Sink Drain Is Clogged

When you throw waste food into the sink, they quickly clog the sink drain. And as the dishwasher is connected to the sink drain, a part of the wastewater will go into the dishwasher.

If you see dirty water from the sink going into the dishwasher tub, a clogged drain might be the culprit.

Sink Drain Is Clogged


Follow two steps to solve the problem.

Step 1: Mix two tablespoons of baking soda with one cup of vinegar. Pour the mixture into the sink drain to remove the clogging.

Step 2: If the clog is stubborn, you can use a plunger to clear the sink drain.

2. Garbage Disposal Cap Isn’t Removed

Sometimes, plumbers can mistakenly leave the garbage disposal cap on. Due to this problem, no water passes through your dishwasher drain.


To solve this problem, take the following 4 easy steps.

Step 1: Carefully remove the drain hose from the dishwasher so that wastewater doesn’t spill on you.

Step 2: Check the garbage disposal cap. Pry it open with a flat-head screwdriver.

Step 3: Check if there is any food debris inside the garbage disposal. If so, clean the waste.

Step 4: Install the garbage disposal to the drain and then connect it to the drain hose. The water from your dishwasher should now drain properly.

3. Drain Hose Is Clogged or Bent

Drain hoses can get clogged over time if you throw a lot of debris into the sink. Sometimes, the hose gets bent and water can’t pass through the hose easily. These problems can cause water to back up in the dishwasher even when it is not in use.

Water Backing Up In Dishwasher


Learn how to unclog the dishwasher in the following steps.

Step 1: Remove the dishwasher from the assembly. Then, disconnect the drain hose.

Step 2: Check if some part of the drain hose is bent. If so, you need to replace the hose.

Step 3: If the drain hose is straight, pour warm water into the hose. It might remove any clogs built up inside.

Step 4: Connect the drain hose to the dishwasher and place the dishwasher correctly.

4. No P-trap Is Used In the Drain

P-traps are used in plumbing systems to let wastewater flow outwards easily. It can’t go back due to gravitational pulls. This works as a dishwasher backflow preventer. If your system doesn’t have P-traps, water can back up into the dishwasher.


Follow the three steps below to set up P-trap.

Step 1: Turn the electrical and water supply off.

Step 2: Take a P-trap. It has two openings. The smaller opening is for the drain hose. Make sure the connection is tight.

Step 3: The larger opening at the top is for the sink drain. Twist it clockwise to connect it to the sink drain. The water from your dishwasher should now drain perfectly.

5. Faulty Check Valve or Water Inlet Valve

A check valve is responsible for letting wastewater drain from your dishwasher. If the valve is stuck open, water can back up into the dishwasher. And if the inlet valve is damaged, water from the sewage line will continue to enter the dishwasher.


To solve this issue, follow the steps.

Step 1: Try moving the rubbers of the check valve with your fingers. If they are stuck and don’t close, they need a replacement.

Step 2: Inlet valves are a bit complex to test. So, you better call an experienced plumber to check the valve and replace it if necessary.

why water backing up in dishwasher


Here are answers to some commonly asked questions about water backing up into the dishwasher.

Q: Can I use chemical drain cleaners to clean clogged dishwasher drains?

We suggest not using any chemical drain cleaners to unclog dishwasher drains. These chemicals can be abrasive and harm the plumbing system.

Q: Can sewage backup into the dishwasher?

Though it isn’t common for sewage to back up into the dishwasher, it can happen if the dishwasher drain hose is directly connected to the sewage drain.

Q: Should I run my dishwasher if it has standing water?

Having about one cup of standing water might not be a problem. But if you have a flooded tub, you shouldn’t run the dishwasher unless the system is checked.


Water draining from the dishwasher is so typical that we often take it for granted. But the problem occurs when the water isn’t drained properly after the cleaning cycle. In the worst cases, water even backs up into the dishwasher. We tried to explain why is water backing up in the dishwasher when not in use and addressed the reasons behind the problem. With the effective fixes mentioned here, you will be able to keep water from backing up into the machine.