Why Your Sink Fills Up When You Run the Dishwasher

Washing dishes by hand is an arduous task, so having a dishwasher readily available in your kitchen is ideal for many homeowners. It saves a lot of time, energy, and even water in many cases. There are some times, however, when owning a dishwasher is inconvenient. Like when issues arise with your dishwasher backing up into the sink. 

It’s actually a common problem for your sink to fill up when the dishwasher runs, but thankfully, there are preventative measures you can take on your own as a homeowner to resolve this.

Here are four causes for your sink filling up when you run the dishwasher and how to solve each of them.

Dishwasher Drain is Clogged

If your dishwasher is backing up into your sink, it might be because the dishwasher drain is clogged. One common way of connecting the dishwasher to your home’s drainage system is to utilize a small drain inlet that exists on the side of a garbage disposal. This connection from the dishwasher to the sink is meant to make drainage easier, but it also means you can end up with the kitchen sink and dishwasher backed up. 

If there is standing water at the bottom of your dishwasher, that means it isn’t able to drain properly, and the drain is in some way obstructed. To resolve this problem, you should check to see if there is anything visible covering the drain at the back or bottom of your dishwasher. 

If you see anything that can easily be removed, do so. Otherwise, you may need to check your dishwasher’s drain hose to clear any obstruction, straighten out a kink in the line, or resolve any other reason for the blockage.

Always be sure to only use dishwasher parts that are suited to your specific dishwasher brand, and use the correct amount of dishwasher detergent to help reduce buildup and the risk of clogging your drain over time. 

Kitchen Sink is Clogged

If your sink backs up when the dishwasher runs, it could be due to a clog in your kitchen sink rather than your dishwasher. If you haven’t checked your kitchen drain in a while or cleared out any debris, now is a good time to do so. Here’s what you can do:

  • Run your garbage disposal if you have one. Let the disposal run for a few seconds before starting your dishwasher to be sure that there isn’t anything in your kitchen drain blocking your dishwasher from working. 
  • Snake the drain. If the garbage disposal doesn’t end up clearing the clog, you can try clearing the drain with a drain snake purchased from your local hardware store. This may help your dishwasher run smoother, your sink drain easier, and stop that annoying dishwasher filling the sink problem.
  • Use safe sink cleaners. Always be careful when using any type of chemicals in your drains since some of them can end up corroding your piping. Some sink cleaners can help clear away bacteria build up and other clogs and are safe for your pipes. Check with your plumbing professional if you’re unsure what’s safe to use on your sink drain.

Garbage Disposal Drain Plug

If you’re dealing with your dishwasher backing up into the sink, then your garbage disposal drain plug could be the culprit. This drain plug can cover the hole where the disposal and dishwasher connect with each other. If it’s left on, the water won’t drain properly, leading to the big problem: the sink backs up when the dishwasher runs.

Thankfully, this is an easy fix. Simply take the garbage disposal drain plug out and your drainage problem should be resolved. 

Air Gap in Sink is Blocked

When your kitchen sink and dishwasher are backed up, that could be because the air gap in the sink was blocked. Some sinks are installed with air gaps. Unfortunately, air gaps can actually prevent the dishwasher from properly draining when they get clogged. 

As a result of this, the sink fills up when the dishwasher runs.

The best way to resolve issues like this is to clean your air gap. Air gaps are typically located at the top of your sink, beside the faucet, and are used as a backflow prevention device. 

To clean it, remove the top cover of the air gap, unscrew the inner protective cap, and then check to see if there is any debris or dirt that can be easily removed. Once it’s cleaned, replace the protective cap and exterior cap and test your dishwasher to see if the issue is resolved. 

Call John C. Flood to Repair Your Dishwasher and Sink

If you work through all these troubleshooting tasks but your sink still backs up when the dishwasher runs, then it’s time to contact professional plumbing repair. 

You can contact our expert technicians online to ask questions about your specific problem or schedule a service yourself online. It’s time to get your dishwasher and sink working right.

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