How To Unclog A Dishwasher & Drain

Failure to drain is a common problem for dishwashers, and many people find themselves in a quandary as to the reason for it.

In this guide you will learn how to troubleshoot a dishwasher that won't drain and how to unclog a dishwasher.​

Dishwasher Troubleshooting

It is important to note that if your dishwasher is not draining all the way and there is just a small amount of clean water in the bottom of your dishwasher, that is not a problem.

There should always be a little water there to prevent the seal from becoming too dry.

If there is a large amount of water, you have true failure to drain. There are many causes for this problem. In this article, we will discuss some of these causes and provide good advice for prevention and dishwasher troubleshooting.

It's easy to see that when your dishwasher will not drain, there are a number of things that may be causing the problem. Generally speaking, the 7 most frequent reasons are:

  • The air-gap of the sink (located near the kitchen faucet) is clogged. Unclogging it will solve the problem.
  • The drain hose that leads from the air-gap into the garbage disposal is clogged. Removing it and unclogging it will solve the problem.
  • The belt that drives the pump is broken or loose. Replacing it with a new drive belt will solve the problem.
  • If your dishwasher has both a drain impeller and a wash impeller, one or both may be broken. Replacing the broken component will solve your problem.
  • In dishwashers that use a drain solenoid to open the drain valve, this solenoid can become stuck. You may be able to fix it by loosening it. If not, you will need to replace the pump assembly.
  • Sometimes the motor can become stuck. You may be able to get it to work again by simply hand spinning it. If this does not work, the motor will need to be replaced.
  • Your wash timer may be broken and may be in need of replacement.

​Generally speaking, if you do not have good results after following simple troubleshooting steps and removing clogs, you may need the services of a professional.

Common Clog Areas

Even if your dishwasher does not suffer dramatic and immediate damage from the introduction of excessive debris, bits and pieces will eventually build up in the drain and/or the drain hose. Fortunately remedying this problem is fairly easy.

Begin by checking the bottom of the dishwasher and dishwasher filter. If there are more than a couple of cups of water in the sump area, you should bail them out.

Dishwasher Filter

Check the drain to see if there are scraps, paper and other types of detritus clogging it. If so, remove them and see if that doesn't solve the problem.

​If clearing the drain doesn't work, remove the end of the drain hose from the nipple that connects it to the disposal or the sink. Put the end of the hose in a bucket and then run your dishwasher. The force of the water draining out may dislodge the clog.

If this doesn't work, you may have to pull out your dishwasher and remove the hose entirely so that you can clean it thoroughly. Before doing so, place a drain pan under the dishwasher because when you remove the hose the un-drained water will pour out.

Other Issues That Affect A Dishwasher Draining

Sometimes a failure of some component of the dishwasher’s mechanisms can cause drainage problems. If your problem is not caused by a clog, you may wish to check the motor and the drain valve.

​Checking your dishwasher’s motor is fairly easy. If your dishwasher is properly plugged in and receiving enough power, when you turn it on it should work. If it simply hums but does not work it means that the motor is not turning and may need to be replaced.

Checking the drain valve is also fairly simple. If you have checked everything else and you're still not getting the results you need, it probably means that the drain valve is not working and will need to be replaced.

Sometimes a dishwasher door latch will wear out and will not keep the door securely shut. This can cause the dishwasher not to drain. Replacement of the latch can solve this problem.

​If you have recently had a new garbage disposal installed, this may cause your dishwasher not to drain. The reason for this is that there is a removable drain plug in all garbage disposals.

If your garbage disposal is not attached to a dishwasher, this drain plug stays in place. If it is, the drain plug should be removed. Sometimes this step is neglected in installation. This is a very quick and easy fix.

Preventative Maintenance

​It is important to remember that your dishwasher is not a garbage disposal! One of the most common causes of failure to drain is a clog in the pump strainer or the dishwasher drain hose. This is an entirely preventable problem.

Although the instructions that come with your dishwasher may say that you do not need to scrape or rinse your dishes in advance of washing, you should err on the side of caution and do so anyway.

Modern dishwashers are equipped with macerators that are designed to grind up soft, small bits of food. They cannot handle chunks of food such as scraps of steak, and they really cannot handle tough, solid debris such as jar labels, twist ties, bones and more.

Be sure that all of these things are properly disposed of and do not find their way into your dishwasher.

If you do have a habit of letting excessive amounts of food and detritus get into your dishwasher, you can count on damage or destruction of your pump/macerator assembly.

This is a fairly costly repair, and sometimes it is an impossible repair. You might end up having to replace your dishwasher if you do not treat it well.

Final Thoughts

While troubleshooting and repair of dishwashers is not rocket science, if you feel daunted by the prospect of repair you should call in a pro.

This is especially true if your dishwasher is under warranty. If you tinker with it, you may invalidate your warranty and end up causing yourself a great deal of expense.

Did you enjoy this guide? Let us know in the comments with your dishwasher troubleshooting​ tricks and fixes.

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