How to Fix and Replace your Dishwasher Overflow Valve?

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The overflow valve is found in the air gap mounted on your sink next to the faucet. When the dishwasher overflow valve is filled with water that it spurts out of the air gap on your sink, you know that something is wrong with the tubes connecting your dishwasher to the correct outlets.

The problem only occurs when you run the dishwasher as the dirty water used to clean the dishes need to go somewhere. You will need to check the air gap and the two hoses connected to its bottom. You can try the method below to troubleshoot your dishwasher overflow valve.

What is the step-by-step procedure on fixing and replacing dishwasher overflow valve?

You will find below the steps on how to fix your dishwasher overflow valve, which is essentially part of the air gap device. If you need to know more about replacing the dishwasher overflow valve, there is an article found on this website about installation of an air gap that best suits that topic. Onto the guide:

Step 1: Turn the water supply valves off before you start doing anything. Removing the hoses may result to the continuous flowing of water. You may also want to turn the electricity to the kitchen circuit breaker off.

Step 2: Remove the air gap or the protruding device installed to your sink or countertop next to the sink. You may uninstall it by using adjustable pliers to loosen the slip joint found underneath the sink from where it is installed.

Step 3: Remove the two hoses connected to the air gap. These are the hose connected to the dishwasher and the hose connected to the garbage disposal. What connects the hoses to the main body of the air gap can either be a slip joint or a hose clamp. Remove them by using pliers. If you need to replace clamps, try:

Universal Dishwasher Clamp Hose

510S COGTzS. SL500

Step 4: Trace the connections of both the hoses and remove them from their sources, which is the dishwasher and the garbage disposal. You may want to check the connections carefully to see if there are any obstructions or clogs.

Step 5: Take the hoses and fittings outside and use a garden hose with strong pressure to wash down the hoses. Use the pressure to wash down any debris, dirt, or obstructions found in the hoses. Also check underneath the sink if there are big items blocking the path of the hoses. Arrange these items accordingly.

Step 6: After all the hoses and fittings are thoroughly cleaned and washed down, reattach the hoses to the proper sources and secure them with slip joints of hose clamps. Return the air gap complete with the cleaned dishwasher overflow valve into the sink where you previously took it. Again, secure it tightly using pliers.

Step 7: Turn on the water supply lines and circuit breaker that you turned off prior to the start of the DIY project. Connect the dishwasher to power after you’re sure that everything is secured in the right places and turn it on. Test if water still comes up to the dishwasher overflow valve.

Step 8: If things are back to the way they were and you found no leaks or clogs, then congratulations on a job well done. Otherwise, you may need the help of a plumber to determine what’s wrong with the line or buy new sets of air gap kit and hoses. Getting a device to control water flow might also help, like the:

APEC Water Systems Auto Shut Off Valve Replacement Part (ASO)

Key Takeaway: Finding out what’s wrong with your dishwasher overflow valve is not that difficult. If you have managed to install the air gap yourself, you will know exactly how to disassemble it and find out the root causes by checking the valves, the connections, and the hoses. This step-by-step guide is aimed at troubleshooting and fixing the problem, rather than replacing any part mentioned in the guide.

As mentioned before, if you need a guide on how to replace any part of the air gap, we suggest checking the article focused on the installation of air gap. You can find air gap replacements like:

Plumb USA – Dishwasher Air Gap, Oil Rubbed Bronze Finish

21tw1GbhPCL. SL500

What causes problems in the dishwasher overflow valve?

When you encounter problems or overflowing in the dishwasher overflow valve, most likely, the problem lies in the air gap, disposal hose port, or the hose connected to the air gap. Either any of these parts are clogged or it is obstructed by something big and heavy.

However, there are other problems that may cause problems in the dishwasher overflow valve such as:

  1. Food particles are stuck in the hose. Instead of going straight to the bin, food particles may get dislodged into the house because of build up of grim and grease that attracts food to stick.
  2. You forgot to remove the plug in the garbage disposal (this is very little minimal error. Ensure to check this before disassembling anything).
  3. The garbage disposal bin is full or there is something obstructing it. Once this happens, no water may go to the bin, which causes the waste to go up to the dishwasher overflow valve.

Key Takeaway: It is important to immediately fix any problems in the air gap and dishwasher overflow valve because it may cause dirty water coming from the dishwasher to be pushed back into the appliance (also called backflow) and contaminate any dishes or utensils inside. Dirty water should be heading straight to the disposal. Remember, wastewater draining back into the dishwasher is a health hazard.


Repairing your dishwasher as soon as it encounters any problems, whether clogs or leaks should be addressed right away. It really doesn’t matter if you are a seasoned handyman or have very little to no idea about fixing things, as long as you understand and know how to follow directions. Problems such as those that involve parts like the dishwasher overflow valve is not that difficult to troubleshoot and fix.

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