How to Fix a Dishwasher That Won’t Drain

May 18, 2020
Dishwasher Repair

Have you opened your dishwasher to find dishes that look clean, but an appliance that is still full of water? Has water started spilling out of your appliance and onto your kitchen floor while it is in use or after? Unbeknownst to you, these two issues are caused by the same problem – a dishwasher that won’t drain.

As it is designed, a dishwasher only fills with a small amount of water in the bottom of the tub that never goes above the door. After each cycle, the wash water is drained away and replaced with rinse water. If the water is not draining after one cycle, it will sit at the bottom of your appliance. However, if it is not drained away after each cycle, the water may instead build up and end up leaking out of the dishwasher as it penetrates the seal or when you open it up next. While the dishwasher door seal is good at keeping splashing water in, overexposure will cause leaks. Which situation you find yourself in can help your deduce what is the cause of your dishwasher not draining, since if you had only water in the bottom, then it did actually drain for one cycle at least.

Do you have a dishwasher full of water and aren’t sure where to start your troubleshooting and repair for it? Try investigating these common culprits when your dishwasher is still full of water.

Checking The Drain Filter

The first problem that you should always investigate when you have a dishwasher that won’t drain on your hands is to check the filter. In an effort to prevent clogs deeper in the drainage system due to food particles or a loose piece of silverware, all dishwashers come with a filter. However, this filter can get blocked by an accumulation of food particles or other items. Once this happens, then the water simply cannot drain away. You will want to locate and remove the filter in order to clean it. If this was the cause, the water should immediately drain away.

Checking the Drain Line

If your dishwasher is not draining, you will want to quickly check the drain line that runs from your dishwasher and connects the appliance to your kitchen sink drain. It should flow up from the bottom of your dishwasher, rise high, and then gently slope back down to where it connects to the kitchen sink. This prevents backflow into the appliance. However, if this drain line does not follow the curve or it is crimped or tangled in any way, this will be the cause of your drainage issue.

If you did find the drain line out of position, you will also want to rewash your dishes after you adjust it. The reason for this being is that the water that was in your dishwasher was backflow or dirty water. As such, your dishes may not be clean.

Drain Pump Issues

If both the actual drain hose and the filter checks out, then it is likely there is an issue with the drain pump. Typically you will find that if you disconnect the drain hose from the sink and lower it below the level of the dishwasher, the water will drain out from gravity. This is a good way to make sure the drain hose is not clogged and also tells you that your drain pump is probably the faulty part. What the drain pump does is that it forces the water up the curve in the drain hose so it is ferried away. The dishwasher needs the drain pump to provide the force. As such, if it is no longer pumping away water, the water won’t get drained away. Typically, you can deduce if the drain pump is fully no longer functioning by running a cycle. You should be able to hear it working when the wash cycle switches to the rinse cycle.

The unfortunate news is reaching the drain pump in your dishwasher can be difficult. In some models, you may need to continue disassembly past the drain filter in order to reach it. However, in most models, you will need to uninstall the dishwasher, turn it so you have access to the bottom of the appliance and remove the faulty drain pump that way. It is a lot of work and often more disassembly than most homeowners are ready to take on. As such, it is advised that if you believe the drain pump is faulty, you contact a professional appliance repair service.

Stuck Check Valve

The check valve works with the drain hose position to help ensure that the wash water doesn’t drain back into your dishwasher. However, if this valve malfunctions and gets stuck in the open position, it will allow water to flow back in. When this is the case, typically you will see just a bit of water in the bottom of your dishwasher since the majority will still get pumped out. Unfortunately, as it is back flow, this also means that your dishes may be contaminated.

The check valve is located between the drain hose connection and the drain pump. By disconnecting the drain hose, you will be able to check if it is open. However, in order to replace it, you will need to uninstall your dishwasher and turn it over.

Did You Recently Install a Garbage Disposal?

One final issue to consider is if you installed a garbage disposal recently. This very specific issue comes from a pretty common mistake. When a garbage disposal is installed, there is a knockout plug that needs to be knocked out. If this step is neglected, it can prevent water from draining out of your dishwasher because it physically obstructs it. If you have installed a garbage disposal in the area, disconnect the drain hose and give the knockout plug a tap to remove it. Once done, you can reconnect the hose and run a quick test wash to make sure that was truly the cause.


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