4 Reasons Your Dishwasher Is Backing Up Into The Kitchen Sink: Best Practices In Unclogging The Drain

A dishwasher can make life easier for you in the kitchen. Who likes being elbow deep in a mountain of dishes? It’s way simpler and easier when you have a dishwasher—simply toss your dirty dishes in the washer, add some detergent, run the thing, and forget about it.

However, when your dishwasher starts backing up into the kitchen sink,  then you have a situation on your hands.

If often goes like this: You start running your dishwasher, and then the kitchen sink starts filling up with water.

Weird, right?

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Even so, it doesn’t take a genius to figure out why water is filling up the sink every time you run the washer. First off, both your dishwasher drain and your kitchen sink flow into the same drainage system. Going by this logic, what happens when you run the dishwasher while there’s a clog in the drainage line? Well, since water follows the path of least resistance, it gets redirected to another drainage point, which could be the garbage disposal, the air gap, or—you guessed it—the kitchen sink.

With that said, there are a variety of reasons why your dishwasher is backing up into the kitchen sink. Let’s go over them one by one and talk about the right solutions.


Clogged Garbage Disposal

A clogged garbage disposal can be a pain in the you-know-where. It’s annoying, smelly, and compromises your family’s health. And yes, it can also cause your kitchen sink to fill up with water when you run the dishwasher.

The last part is hardly surprising. After all, the garbage disposal and the dishwasher are connected to the same drainage pipe. If water gets stuck inside the garbage disposal, then the dishwasher won’t be able to drain properly. This causes the air gap or the sink to leak water, not to mention cause water to pool at the bottom of the dishwasher.

How to fix a clogged garbage disposal

In most cases, the reason why a garbage disposal unit gets clogged is is because the drain plug was left on after the device was installed. With the plug on, water has nowhere to go but towards the sink.

The only solution, of course, is to remove the drain plug. If that doesn’t fix it, running the garbage disposal with more water than usual should be able to dislodge the blockage.

Obstruction in the Air Gap

The air gap, which is located on top of the kitchen sink next to the faucet, works to prevent drain water from backing up into your dishwasher, thus preventing contamination. But what happens if the air gap itself becomes clogged and you start running the dishwasher?

You guessed it. The sink starts filling up with water.

But what causes a clogged air gap in the first place? There are two possible reasons for this: first, the seal might be damaged; second, there might be a blockage inside the pipe connecting the dishwasher to the air gap.

How to unclog the air gap

To remove the blockage in the air gap, simply remove the top cover followed by the inner cap to have a better view of the air gap’s interior. Then remove any dirt and debris you will see in there. If you’re having difficulty removing both the cover and the cap, using a 12-inch bottle brush helps.

If the clog is in the portion of the pipe between the dishwasher and the air gap, using a plumber’s snake is the best solution.

Jammed Kitchen Sink

Is your kitchen sink overflowing? Food scraps and debris often go down the kitchen sink, causing blockages that slow down the drainage of water or cause water to back up when the dishwasher runs.

The best thing you can do at this point is to remove all the food scraps before the clog gets worse. There are different ways to go about it.

  • Turn on the garbage disposal. If your sink won’t drain, try running water through your garbage disposal for a few seconds before running the dishwasher. This helps you determine if there are food morsels blocking the water going from your dishwasher to the sink.
  • Use a home drain cleaner. Using a home drain cleaner is an effective way to clear blockages from a kitchen sink drain. First, remove the pop-up stopper to get a better view of the interior. Pour a cup of boiling water into the drain and follow it up with a half cup of baking soda and then a half cup of vinegar. Replace the stopper and wait for 10 minutes. Once the minutes are up, pour hot water into the drain. Lastly, run the hot water from to remove any residual debris from the drain pipe.
  • Use a drain auger. If the above methods don’t work, you can , otherwise known as a drain auger. As the name implies, this tool is shaped like a coiled snake, but with a handle on one end and an auger tip at the other. Just push the snake into the drain pipe until it comes in contact with the clog. To remove what’s causing the obstruction, you either have to break it apart or twist the snake around (causing the food scraps to cling to the auger tip) before pulling it out.

Blockage in the Dishwasher Itself

What happens when the clog is in the dishwasher itself? As always, the water takes the path of least resistance, so expect most of the water to come up through the kitchen sink. One effective way to determine if your dishwasher is clogged is to check if there’s a lot of standing water at the bottom. You’d also do well to check the drain hose for any residue buildup.

How to unclog a dishwasher

Sometimes, the reason why your sink is backing up water is due to a clog inside the dishwasher. After all, blockages in the dishwasher can mess up the drainage process. Unclogging a dishwasher can be a complicated task and you must follow the proper procedures to avoid compromising or damaging the kitchen appliance.

Here’s a breakdown of all the steps to unclog your dishwasher the right way.

Step 1: Unplug the dishwasher from the wall outlet

As is the case with any electrical appliance, you need to unplug your dishwasher from the power source to avoid accidents.

Step 2: Detach the kickplate

See the piece of metal just below the dishwasher? To pull out the kickplate, remove its fasteners first with a screwdriver. Place the plate and the screws to one side for retrieval later.

Step 3: Inspect the drain hose

You get instant access to the drain hose once the kickplate has been removed. The drain hose is the hose connecting the dishwasher pump to the drain. Before pulling it out, set a wide pan below the part where the hose and the dishwasher meet to catch any spillage. Make sure you have a dry rag at the ready in case some of the water falls on the floor.

Step 4: Remove the drain hose

Most dishwashers have a wire clamp attaching the hose to the pump. Loosen the wire clamp with your pliers and then gently pull the hose out.

Step 5: Loosen the clogs

Grab hold of the hose and then bend each section back and forth, working on a different segment every few inches or so until you break up any clogs along the hose’s entire length.

Step 6: Flush out the loosened clogs with a garden hose

Now that the clogs are loosened up, put them away for good by running hot water through the hose.

Step 7: Unclog the recirculation hose

Now that you’ve successfully unclogged the drain hose, it’s time for you to do the same with the recirculation hose. In case you’re not aware, that’s the second hose running from the pump. To unclog the recirculation hose, follow the same procedures you did with the drain hose.

Step 8: Replace the hoses if the above steps didn’t work

If the clogs are far too stubborn to be removed, the best course of action is to replace the hose. You can buy new hoses at your nearest home improvement retail store or hardware store.

Step 9: Plug the hoses back on

Set the hoses back into the dishwasher and then re-fasten the wire clamps until all components are securely back in their original positions.

Step 10: Run the dishwasher again and check for backups and leaks

Run the dishwasher once the hoses are connected again. If you’re not noticing any water backups or leaks, then pat yourself on the back for a job well done! If there are still leaks or backups, check to make sure if the hoses are securely attached.

Signs that your dishwasher is clogged

An overflowing kitchen sink is but one symptom among many of a clogged dishwasher. If you want your dishwasher to last for many years, you must be always on alert for early warning signs so that you can immediately carry out the necessary repairs.

Here are the signs you need to look out for if you want to keep your dishwasher to continue draining water efficiently.

Dishwasher or sink is draining slowly

If your dishwasher or sink is taking far too long to drain, then that’s a sign that there’s a partial clog in the sewer line. The clog may not be substantial enough to cause water to overflow, but ignore it for too long and you’ll end up staring down a clogged drain sooner or later.


If you’re hearing a gurgling sound every time you run the dishwasher, then chances are you have clogged vents. When there’s gunk or mineral build-up inside the drainage, it becomes more difficult for water to drain, causing those unholy sounds.

Your dishes aren’t “clean” enough after running the dishwasher

If you’re starting to notice that your dishes don’t look or feel like they’re washed enough, something’s obviously wrong. And chances are the fault lies with your dishwasher. After all, your dishwasher won’t be as effective if it’s not draining water properly. To find out for sure whether the cause is insufficient water, try running the dishwasher with additional detergent. If you’re still getting the same results, then the mainline or secondary kitchen line is probably clogged up.

There’s standing water at the bottom

Blockages in the dishwasher prevent water from draining following a cycle, causing more liquid to collect at the bottom. That can’t be good considering that standing water often results in the buildup of mold and bacteria,  which can contaminate the dishes. That’s a health hazard you want to avoid at all costs.

How to  prevent future clogs in your drains

Whether you’ve experienced a clogged drain before or not, it goes without saying that you’d want to prevent one from occurring in the near future. An obstructed dishwasher is a nightmare to deal with, not just because washing dishes the traditional way is a drag, but also because of the mess and unpleasant odors that come with it. Thankfully, there are many ways you can prevent your dishwasher from getting clogged up.

Clear the drain daily

You must clear your dishwasher’s drainage system of food scraps after each use to prevent gunk buildup. Just take out the bottom dish rack to get access to the dishwasher drain and then remove any food that might be stuck there. A clean drain not only helps your dishwasher clean your dishes more efficiently, but it also prevents damage.

Clean your dishwasher filter regularly

Most dishwashers come with a detachable screen filter to catch food scraps and mineral content, thus preventing them from blocking your dishwasher’s drain. Clear the filter of food morsels after every use to avoid damage. To find out how to remove the screen filter, read the instructions that come with the package (for most dishwashers, you only need to rotate the filter counter-clockwise to remove it).

Rinse your plates properly

This part’s obvious but bears emphasizing: your dishwasher is meant to wash grease and food stains, not to get rid of food leftovers. Even small food chunks can cause your dishwasher drains to clog up over time. After every meal, make sure to dispose of food leftovers properly before putting your plates into the dishwasher.

Use a drain cleaner regularly

Hard water (water with large mineral deposits) is notorious for causing clogs in pipes and appliances. If you want to prevent mineral deposits from collecting in your drains, using a drain cleaner on your dishwasher on a regular basis should help. But you’d want to avoid using chemical drain cleaners, as explained in an earlier section.

One popular yet non-corrosive drain cleaner solution you can use is baking soda with lemon juice. This mixture works the same way as vinegar. Sure, it’s a little more expensive, but the fact that it smells so much better will make it worth your while. Put the mixture in the drain and wait for it to foam. Once it’s foamed up, run the hot water for 15 minutes and wait for the mixture to work its magic.

Run a hot water cycle

Grease and oily stains are infamous for causing clogs in drainage systems. However, all it takes to prevent grease buildup is to run a hot water cycle regularly. Why? Because hot water is far more effective at removing oily dirt than cold water.

When running a hot water cycle, it’s advisable that you set the water heater’s thermostat to 120°F– not too hot but warm enough to get rid of oily dirt. Ideally, you should perform this procedure at least 3 times each week.

Mistakes to avoid when cleaning drains

Everyone should clean their drains regularly — that’s already a given. The problem? Most homeowners are cleaning their drains the wrong way, which can cause a wide range of problems.

Common mistake #1: Using a pressure washer or garden hose

It can be quite tempting to spray away at a clogged drain with a garden hose, but doing so is a waste of time for one simple reason: it doesn’t always produce the intended result. This cleaning method only dislodges the gunk on a surface level, thus leaving a sticky residue behind.

Common mistake #2: Using chemical drain cleaners

Granted, using chemical drain cleaners can prove effective at removing clogs in drains. However, there’s one major drawback: it weakens and damages your pipes as well. In fact, the chemicals contained in the drain cleaner can further damage the pipes until they burst, possibly causing physical harm and respiratory issues to those who are nearby.

Most chemical drain cleaners contain sodium hydroxide or sulfuric acid, which have a corrosive effect on organic materials and metals. If you want to use a drain cleaner, use biological or non-corrosive drain cleaners recommended in an earlier section discussed in this article.

Common mistake #3: Using foreign objects

One of the worse things you can do is grab a foreign object like a coat hanger or kitchen knife to try to fish out a clog from a drain.

There are numerous reasons why doing this is a bad idea. First off, most blockages are too far below the drain for any foreign object to reach. Most importantly, there’s always the chance that the object will fall down the drain, making matters worse.

We’d also like to take this chance to let you know about our articles on why there’s a sewage backup in your basement, and our article on toilets backing up.

Getting help from pros

You’re now reached this far into the article because of two possible reasons. First, you’ve performed the above procedures but with little to no results to show for it. Second, you’ve read most of the article but you simply don’t have the time or the inclination to go through with the procedures, and you’re now looking for other possible options.

Either way, your dishwasher is still making your life a living hell. Something needs to be done because it’s not going to fix itself.

So, what’s a homeowner to do?

The answer is as simple as it is obvious: Hire a professional.

In the final analysis, hiring a pro is always the best possible option. After all, a professional contractor not only has the experience, he or she also has the tools and skills needed to get the job done. More importantly, a professional is more likely to perform the correct procedures. This provides you with the assurance that you won’t experience the same issues again for a long time.

Which brings us to the tough part: finding the best contractor for the job.

Here’s one golden rule you should follow when prospecting for a contractor: solicit as many quotes as you can from as many reputable contractors you can find.

We give you this advice for one simple reason: the more choices you have, the higher your chances of finding the best contractor for the job.

After all, having many choices presents you with more opportunities to pick a contractor who can address your specific needs and charge you a price that you can afford.

To look for contractors, simply go to the internet and do local Google searches (and read reviews while you’re at it). You can also ask family and friends for referrals.

If you don’t have the time or the patience to do all those, either… fret not. There’s a better option.

How would you like to receive up to four quotes from competing contractors with the least amount of effort possible? The best part? It’s all FREE!

All you need to do is just fill out the form on this site with your details and click on “Get Free Quotes”! Once submitted, we’ll go through the information so we can understand your project requirements.

We’ll then send your information to selected professionals within your area. Interested contractors will then contact you to talk about your project so that they can provide you with an accurate quote afterward.

It’s that easy!

Also, there are no commitment involved. If none of the offers are to your liking, you can simply refuse them all and go about your day like nothing happened.

Ready to have your drains fixed and put your life back on track? Fill out the form now!

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