Dishwasher Backing Up Into Sink (Causes + Solutions)

Dishwasher Backing Up Into Sink (Blog Cover)

If your dishwasher is backing up into the sink, you have a problem on your hands. One of the most common plumbing problems involves water from the dishwasher backing up into the sink. It’s a messy problem that requires immediate attention.

A few different things can cause a dishwasher to back up into the sink, so Plumbing, Heating, and Air Alliance outlines those causes and provides some simple fixes.

A Clog in the Sink Drain

A clogged sink drain is the first and most common cause of dishwasher water backing up into the sink. In this situation, the first thing you have to do is unplug the garbage disposal. However, you can never be too careful and should never reach into a drain while the garbage disposal is plugged in. 

If the drain is minor, you may be able to reach down and remove whatever is causing the clog with your (gloved) hand. However, it’s not a good idea to try to deal with a clog by using a liquid drain cleaner. These products can do more harm than good. 

Instead, call a professional plumber who will likely correct the problem using a drain snake.

Dishwasher Clog

Sometimes, the line to the dishwasher might be clogged, which is similar to a clogged sink. As a result, you would handle it the same way. However, you should also check to see if the drain plug has been removed and if the dishwasher has been installed recently. 

If the drain plug hasn’t been appropriately removed, it could cause other problems for the appliance. 

Problems With the Air Gap

The air gap (usually installed next to the sink faucet) may also have a clog. Not all sinks have an air gap, so obviously, this won’t be the issue if the sink you’re servicing doesn’t have an air gap. However, if it does, it’s worth checking to ensure the air gap isn’t clogged, as this can also lead to dishwasher water backing up into the sink. 

The purpose of an air gap is to prevent backflow, but when the dishwasher is old or overused, the air gap can become clogged. As a result, the dishwasher will be unable to drain correctly. 

The clog must be cleared from the air gaps when this happens. In addition, plumbers may ensure that the hoses that lead into the air gap aren’t kinked, which will also cause draining problems.

The Opposite Issue

It’s also worth noting that you may have the opposite issue on your hands. We mean sink water running into the dishwasher. This can put dirty sink water into the dishwasher, which is obviously not good. 

When this happens, you should check to see if there are any clogs in the connected components. For example, check the sink drain, the dishwasher drain, and the air gaps. 

In some cases, you will need to hydro jet the clog out. Hydro Jetting is an excellent service because it’s safe for the pipes and is very effective at removing tough-to-reach clogs. 

Garbage Disposal Issues

Another reason you may see water back into the sink is that the garbage disposal is clogged. For some older kitchens, the dishwasher drains into the garbage disposal. So when food waste and grease clog up the garbage disposal, it can also result in dishwasher water coming up through the sink. 

You may need to reach the garbage disposal from underneath and manually crank it to clear the clog if you can’t simply reach down and remove it. Of course, you should call a plumber to handle the job.

Plumbers should also use a flashlight to peer down into the drain to see if they can spot it and if it’s local enough to reach down and clear it by hand. Frequent disposal clogs may indicate dull blades that aren’t processing food waste correctly. 

In some cases, the blades will have to be replaced. But you can generally grind up eggshells to help keep the blades sharp. Pouring a little white vinegar down the drain and disposal from time to time will also help prevent clogs. 

Any time you are dealing with the garbage disposal, you should disconnect it. It bears repeating because it is a safety issue; the last thing you need is an accident. Finally, don’t forget to call a professional plumber, as trying to unclog drains can result in severe injury.