It’s indeed quite a mystery when your dishwasher fills with water even when you’re not using it. Luckily, this problem usually only needs a simple fix.
So let’s talk about what causes this error and how you can resolve it.
Why does your dishwasher fill with water when not in use?
A dishwasher fills with water even when not in use when the sink drain is clogged or the drain hose has no air gap device. A damaged flapper and inlet valve can also cause the issue.
Fix this by unclogging the sink drain and drain hose. Ensure that the drain is connected to an air gap.
If your dishwasher still fills with water after doing the above, you can also try the following steps:
- Verify that the check valve isn’t clogged and can move freely.
- Test the water inlet valve and make sure that it’s working correctly.
Keep reading below if you want a more detailed guide on how to perform these troubleshooting steps.
Important note: For your safety, unplug your dishwasher and turn off the water supply valve before doing any repairs. Press the power button and make sure that it no longer lights up.
Causes and Solutions
There are 5 possible reasons your dishwasher fills with water even when it’s idle.
- The sink drain or garbage disposal is clogged.
- The drain hose is clogged or bent.
- The drain hose has no air gap or high loop.
- The check valve is stuck or worn out.
- The water inlet valve is malfunctioning.
Here are a few quick suggestions on how to troubleshoot each issue.
| Cause | Solution |
| Clogged Sink Drain or Garbage Disposal | Disconnect the drain hose from the garbage disposal and verify if the garbage disposal cap has been removed. Check your sink drain or garbage disposal and ensure they aren’t clogged with food waste and other debris. Use a mixture of baking soda and white vinegar to clean them. |
| Clogged Drain Hose | Uninstall the drain hose from the dishwasher and the sink drain. Run some water inside the drain hose to verify if anything is clogging it. Clean the drain hose and remove the clogs in between. Straighten the hose and make sure that it isn’t bent or kinked during reinstallation. |
| No Air Gap or High Loop | Connect your drain hose to an air gap to prevent the wastewater from flowing back into your dishwasher. You can also fasten the drain hose under the countertop to make a high loop that functions the same way as an air gap. |
| Damaged Check Valve | Access your drain pump and inspect the condition of the check valve. Make sure that the check valve is installed in the right position and that there are no clogs that are keeping it open. |
| Malfunctioning Water Inlet Valve | Access the water inlet valve under your dishwasher and test it to verify it’s working correctly. Replace the entire assembly if it’s damaged. |
Clogged Sink Drain or Garbage Disposal
One of the main reasons water is filling your dishwasher is that the sink drain or garbage disposal is clogged by food waste and other debris coming from the kitchen sink.
This can be caused by leftover pasta, bone pieces, meat chunks, or fatty build-up.
When this happens, the wastewater from your drain hose can’t get out and flows back into your dishwasher. This is why you see water at the bottom of your tub even when the cycle’s already over.
If your drain hose is newly connected to a garbage disposal, it is also possible that the cap covering it was left intact during the installation.
Solution: If your dishwasher is connected to a garbage disposal system, check if the cap where the drain hose is attached has been removed.
If you’re not sure how to perform this, follow the steps below.
- Step 1: Prepare a pan or towel to catch water spills when you disconnect the drain hose.
- Step 2: Loosen the lock and slowly detach the drain hose from the garbage disposal.
- Step 3: Knock the garbage disposal out using a screwdriver and a hammer if it’s still intact.
- Step 4: Uninstall your garbage disposal to remove the broken cap pieces inside. This will prevent the debris from clogging the disposal or pipes.
- Step 5: Reinstall the garbage disposal properly and reconnect the drain hose. Ensure that the connection is tight and the drain hose isn’t bent irregularly.
Clean your garbage disposal while it’s uninstalled. Remove any dirt build-up or large chunks of food waste that could cause clogging and draining errors.
If your dishwasher is connected directly to a sink drain, make sure that it isn’t clogged with various food scraps such as bones and fat.
Unclog your sink drain with the following steps:
- Step 1: Pour a pot of boiling water or a mixture of baking soda and vinegar down the sink drain.
- Step 2: Use a plunger or drain snake to force any food residue down the drain.
- Step 3: Remove the trap and check it for blockage.
- Step 4: Reinstall the trap once it’s cleaned.
Clogged Drain Hose
The drain hose plays a major role in keeping wastewater away from your dishwasher.
If the drain hose is clogged by leftover food, glass pieces, or plastic debris, the draining process will slow down or stop completely.
The problem won’t be easily noticeable if the clog is closer to the drain than to your dishwasher. In this case, the water will still drain out but flow back when it reaches the blockage.
The same can happen if your drain hose is bent or kinked because your dishwasher is sitting on top of it.
Solution: First, pull out your dishwasher from the cabinetry and check your drain hose for any bends.
Inspect your drain hose and make sure that the dishwasher isn’t sitting on top of the hose, pinching it shut.
Next, check the drain hose for clogs or blockages.
To do this, disconnect the drain hose from both ends and pour some water inside it to test if the water can pass freely. If the water is restricted, remove the clogs inside the drain hose.
It is also possible that the water inside the hose has frozen, causing the clog.
If this is the case, dissolve a spoon of salt in boiling water and pour it carefully inside the hose. Test the hose again and see if all the frozen water has dissipated.
No Air Gap or High Loop
The air gap is a small item mounted above the sink near the faucet. It elevates your drain hose before it’s connected to the kitchen sink drain.
The air gap has an “in” hose and an “out” hose. When your drain pump pushes the dirty water up your drain hose and into the “in” hose, it passes the air gap and slides down the “out” hose into the sink drain.
Gravity prevents wastewater from flowing back into your dishwasher when you’re not using it.
Some households use a high loop instead of an air gap. If the plumbing codes in their area allow it, many prefer the loop as it is a much cheaper alternative.
However, if your drain hose is directly connected to the sink drain or garbage disposal without an air gap or a high loop, the wastewater can flow right back into your dishwasher even after the cycle is over.
This commonly happens when your sink drain or garbage disposal is close to being filled with food waste.
Your dishwasher’s drain pump forces the wastewater to enter the sink drain or disposal while it’s on. However, when the impeller stops spinning, some of the water flows back to your dishwasher because the drain hose is laying flat on the floor.
Solution: Check your drain hose’s connection and verify if it’s connected to an air gap or has a high loop.
If there’s a hole above your kitchen sink that has no air gap device installed, you can buy one and install it yourself. To do this, follow these steps.
- Step 1: Unplug your dishwasher and switch off the water supply valve.
- Step 2: Locate the air gap hole in your counter and remove the disc cover.
- Step 3: Connect your drain hose to the smaller leg of the air gap device. Use a steel hose clamp to secure the connection.
- Step 4: Connect the air gap to the sink drain or garbage disposal using a tube and secure it using a hose clamp as well.
- Step 5: Push the air gap device through the hole in the counter and thread the nut to lock it in place.
- Step 6: Place the vanity cover back on the air gap and run a cycle on your dishwasher to test it.
If you prefer a high loop instead of an air gap, first make sure that the plumbing codes in your area allow this. If it’s permitted, follow the steps below to make a high loop for your drain hose:
- Step 1: Unplug your dishwasher and turn off the water supply.
- Step 2: Disconnect the drain hose from the garbage disposal or sink drain.
- Step 3: Loop your drain hose and fasten it on the underside of the countertop.
- Step 4: Make sure that the loop is at least 15 – 20 inches higher than its connection to the sink drain or garbage disposal.
- Step 5: Reconnect the drain hose to the sink drain or garbage disposal and tighten the connection using the hose clamp.
Damaged Check Valve
Another likely cause of your dishwasher filling with water is a damaged or stuck check valve.
The check valve or “flapper” is a rubber component inside your drain pump that only opens one way to prevent wastewater from flowing back once it’s drained.
However, the flapper is also prone to clogging and wearing out. When this happens, the flapper will be stuck in an open position and allow a backflow.
Solution: Remove the check valve and clean its housing area. Make sure that the check valve isn’t damaged and test it with your finger to verify that it can move freely.
If the valve is damaged, you’ll need to replace it. Simply buy the right type of check valve for your dishwasher model and replace the old one.
Make sure that the check valve is facing the right way or your dishwasher won’t drain correctly.
Malfunctioning Water Inlet Valve
If the water filling your dishwasher while it’s idle is clean water, then a malfunctioning water inlet valve is the likely culprit.
The water inlet valve is an electrical device that opens and closes to control the amount of water that’s coming inside your dishwasher.
If the inlet valve becomes faulty, it can be stuck in an open position and let the water in even when your dishwasher is not in use.
Solution: First, make sure that your dishwasher is unplugged to avoid electrocution. Remove the kick panel below by unthreading the screws.
Access the water inlet valve and remove the wire connections. Perform a continuity test on the water inlet valve to make sure that it’s working correctly.
To perform the test, follow these steps:
- Step 1: Adjust your analog tester to the lowest setting of ohms of resistance.
- Step 2: Calibrate the meter by touching the probes together while adjusting the needle to read zero.
- Step 3: Use the probes to touch the water inlet valve’s solenoids.
- Step 4: Check the reading indicated in the tester. If the reading is between 500 – 1500, then the valve is working fine.
- Step 5: Replace the water inlet valve if the needle does not move at all.
You can also uninstall the entire valve assembly to check it for clogs and other mechanical issues. Look for any signs of damage such as cracks or electrical burns.
Avoid repairing the valve by yourself if it’s damaged. Just replace the entire inlet valve assembly or call a professional to fix it for you.
We hope that this guide helps you uncover the mystery of why your dishwasher fills with water when not in use. With a little experience with tools and repair, you can easily solve this problem by following the steps above.
However, if you find some of these steps a little overwhelming, you can always call your dishwasher’s support center for help or hire an expert to perform the repair for you.
