Is the Dishwasher Backing up into Sink?

dishwasher backing up into sink

No disagreement on the topic that the kitchen is the primary interest of every household. Consequently, a kitchen sink is the most used fixture that bears half load of cleaning for your entire home. So, when the kitchen sink backs up, it undoubtedly gives you a minor heart attack.

Besides, when you find the dishwasher backing up into sink, then you will fall into miserable condition. Because the dishwasher and kitchen sink are the most used item. So, baking up water creates hassle in kitchen work and slows down your whole housework efficiency.

But what is the reason?

Well, a dishwasher can back up into the sink for many reasons. The most common issue is malfunctioning dishwasher pump, short air gap, blocked or clogged drainage pipe, improper dishwasher installation and a few more.

No matter the reason behind it. Now the question is, how can you get rid of this problem? Do you need immediate professional help? Can you solve it by yourself? Or do you need to replace your sink or dishwasher?

The question is many but doesn’t worry, we have pointed out the possible reason for this occurrence and given a practical solution.

So, without panic, read this article and decide whether you can solve it yourself or need professional help.

Why Dishwasher Backing up into Sink?

You might notice the water backing up issue when you run the dishwasher and frequently get unsourced water into your sink. That is the time you will understand your dishwasher backing up into sink. Generally, the dishwasher and sink share the same drainage system. As a result, both get affected if any of them have a problem.

Let’s see the possible cause of the issue.

1. Malfunctioning Dishwasher

A malfunctioning part can cause water to back into your sink. Malfunctions in the dishwasher can occur for various reasons, such as a faulty pump or valve, a damaged drain hose, or a clogged filter.

You can identify this quickly by checking your dishwasher bottom. Generally, the dishwasher drains all used water through the drainage system, but when you see the bottom of the dishwasher is filled up with standing water. There is something fishy happening in the dishwasher mechanism.

  • Faulty Valve or pump: The dishwasher valve regulates water flow into the dishwasher. If it is not functioning correctly, it can cause water to back up and overflow into the sink.
  • Dishwasher Hose Loop or Drain Hose: Sometimes, the drain hose is not looped high enough under the sink. It can happen if the hose loop is not installed correctly or, over time, it becomes loose from its original space. Basically, the dishwasher drain hose loop is installed higher than the kitchen sinks; if it moves from its actual area, it can cause water to flow back into the dishwasher, leading to backups.
  • Block or Clogged Dishwasher Drainage: If the dishwasher drainage system is blocked or clogged due to debris, food particles, grease and another component. It can cause water to overflow and back up into the sink.
  • Clogged Dishwasher Filter Basket: A dishwasher features a filter basket that catches food debris and other things from entering the drain. If it gets blocked, slow drainage and water backing up are possible.  
  • Improper Dishwasher Installation: Unprofessional and improper dishwasher installation can result in drainage problems. Eventually can cause water to back up into your kitchen sink.

2. Clogged Sink Drain

A dishwasher always not the culprit for water backing up into the sink. It can also happen to clogged or blocked kitchen sink drainage system. Yes, if the kitchen sink drain gets clogged, it prevents dishwasher water drainage through the pipeline. As a result, water and debris start back up into the sink instead of draining.

3. Problem with Air Gap Device

A dishwasher air gap is a cylindrical attachment that connects the drain of your kitchen sink to the dishwasher. Its purpose is to ensure that dirty water does not flow back into the dishwasher while preventing water from exiting during a wash cycle.

However, the air gap also shares the same kitchen sink and dishwasher drainage. When the kitchen sink’s main sewer line gets clogged, it hampers the air gap. Consequently, prevent dishwasher or ki

4. Conflict with Garbage Disposal

Like air gaps, garbage disposal sometimes creates an issue with normal water flow. Firstly, suppose your garbage disposal becomes clogged or blocked. In that case, it can prevent water and debris from draining correctly and cause a backup into the sink.

Secondly, improper garbage disposal installation may lead water back into the sink. Suppose the person who installed the dishwasher did not remove the plug from the disposal port where the dishwasher drain line is connected. In that case, it will result in a blockage.

5. Using Work Detergent

When it comes to using detergents in a dishwasher, it is crucial to use the right kind. Dishwashers require a particular type of powder detergent that does not create suds. It is essential because it allows the washer to drain completely after each cycle.

Using an accurate detergent, such as a liquid detergent, can result in excess suds, making it difficult for the dishwasher to clean your dishes properly. It can lead to residue and buildup in the dishwasher, slow drainage, or water backing-up issues.

Sing of Water Backing up into Sink

Although water backing up into the sink is a visible issue, sometimes it gives some signs first and then happens later. If you can identify those signs, you can prevent extreme water backing up.

  • It would help if you frequently examined whether your sink drains usually or more slowly than usual.
  • If you find foul odor coming from your sink, it could be a sign that your sink will soon back up.
  • Sometimes, when water passes through the drain, it creates gurgling noises, which we often overlook. But be careful; it is also a sign your sink or dishwasher has faced an issue.
  • Lastly, if the water leaks from the sink’s overflow hole, it indicates that the water is not draining correctly.

Fixing a Dishwasher Backing up into Sink Issue (Step-by-Step Solution)

As mentioned, the dishwasher backing up into the sink is occurring for the dishwasher problem and kitchen sink drain. So, let’s see the solution to dishwasher problems.

The List of Tools You Will Need

  • Flashlight
  • Pliers
  • Plunger
  • Drain snake
  • High-loop kit (if necessary)
  • Dishwasher manual
  • Screwdriver (if necessary)
  • Plumbing snake or drain cleaner
  • Rubber gloves
  • Bucket
  • Towel or cloth
  • Toothbrush

Step 1- Turn off Power Line and Water Line

Before starting, turn off the power line of the dishwasher and the water line of both the kitchen sink and dishwasher. It will ensure you can safely inspect and solve the problem without interruption. Double-check and move to the next step.

Step 2 – Clean the Dishwasher Drain or Sink Drain

The first thing to do is check the dishwasher or sink drain for any visible clogs or blockages. Begin it by opening the dishwasher racks from the drain grate. You will find it at the bottom of the dishwasher and need a screwdriver to open it.

  • First, use a plunger or drain snake to remove any clogs or debris.
  • Secondly, pour hot water and set it there for several minutes.
  • Thirdly, rinse vinegar into the drain and add baking soda. Please wait 15 minutes to set it properly and pour hot water. This mixture will remove further clogged, grease, detergent scum and other things from the drainage system.
  • Next, you must turn on your dishwasher and set it to run a rinse cycle with the highest heat setting.
  • Finally, check if the water backing issue is solved. If the water is still backing up into the sink, move to the next step.

Step 2: Check the Dishwasher Drain Hose

The next step is to check the dishwasher drain hose. Again, you need to turn off the power switch and water line. However, the drain hose is usually located underneath the sink and is connected to the garbage disposal or sink drain. Ensure the hose is not kinked or pinched, which can cause water to back up into the sink.

  • Now take a pillar and loosen the hose clamp to disconnect it from the drain system. After removing it, use a flashlight to see any visible clog in the hose pipe.
  • It would help to have a bucket to collect water from the hose pipe and a towel to stop the water from the spare.
  • Therefore, if you see any clog and debris, flush the hose pipe with hot water to remove the clog. You can also use the vinegar and lemon juice mixture inside the hose to remove the clog.
  • Moreover, if you see the hose is damaged and leaking water, you must replace it urgently.
  • After cleaning or changing the hose pipe, again attach it to the drain system and run the dishwasher to check whether the water backing up issue is solved. 

Step 3: Check the Dishwasher Loop Hose and Garbage Disposal Setup

Generally, the dishwasher drains into a sink with garbage disposal. So, you must ensure that the dishwasher drain hose is looped higher than the disposal drain inlet. Because if the loop is not higher than the garbage disposal, it will create a barrier and prevent dirty water from flowing into the drain.

  • Besides, a garbage disposal can get clogged with food parties, leading to the water backing up into the sink. In that case, you must run the cold-water line and the garbage disposal for a few minutes.
  • Next, run hot water for a few minutes to clear all grease or clog behind these water backing-up issues.
  • Moreover, if you don’t set up the loop hose correctly, you may need to adjust it or add a high-loop kit.

Step 4: Clean the Clogged Drainage Filter

You must clean the dishwasher filter regularly because it collects food particles and debris. Refer to your dishwasher’s manual for instructions on how to clean the filter. If the filter is clogged, it can cause the dishwasher to back up into the sink.

Step 5: Clean the Clogged Drainage System

If the sink drain and dishwasher drain hose is not clogged and the dishwasher is still backing up into the sink, there may be a clog in the drainage system. You can use a plumbing snake or a drain cleaner to clear the clog.

Step 6: Clean the Air Gap System

You have cleaned the clogged drain, garbage disposal, and sink drains and fixed the hose loop. But do you still face the water backing up issue? If yes, then it’s time you must check your air gap system.

It is usually mounted on the countertop next to the sink. It looks like a small cylindrical tower with a cap on top.

  • First, turn off the power to the dishwasher by unplugging it or turning off the circuit breaker that powers it.
  • Remove the cap from the air gap tower and set it aside.
  • Look inside the tower and use a toothbrush or a small bottle brush to clean any debris or buildup that may be present.
  • Use a small amount of vinegar to clean the inside of the tower. Pour the vinegar into the tower and let it sit for a few minutes to dissolve any buildup.
  • Use a clean cloth or towel to remove residue from the air gap tower.
  • Reattach the cap to the top of the air gap tower.
  • Finally turn the power back on to the dishwasher and run it through a cycle to ensure everything works properly.

Step 7: Fix the Faulty Valve and Pump of the Dishwasher

To fix a faulty valve or pump in your dishwasher, you can follow these steps:

  • Turn off the power to the dishwasher by unplugging it or switching off the circuit breaker.
  • Locate the valve and pump in the dishwasher. You can usually find these components under the dishwasher. So, you may need to remove the bottom panel to access them. You can use a pillar or screwdriver if required.
  • Next, inspect the valve for visible damage, such as cracks or leaks. If you notice any damage, you must replace the valve.
  • Check the pump for blockages or obstructions, such as food particles or foreign objects. If there is a blockage, remove it and test the pump to see if it functions correctly.
  • However, whether the valve and pump appear in good condition, use a multimeter to test them. Set the multimeter to the ohms setting and touch the probes to the terminals on the valve and pump. If there is no continuity, you must replace the faulty component.
  • Otherwise, you can purchase a replacement part online or from a local appliance store if you need to replace the valve or pump. Make sure to get the correct part for your dishwasher’s model.
  • Once you have the replacement part, follow the manufacturer’s instructions to install it. Make sure to turn off the power to the dishwasher before starting any repairs.

Step 7: Solve Improper Installation

If none of the above steps works, there may be an issue with the dishwasher’s installation. Faulty valves or pumps, improper drainage hose installation, or incorrect air gap installation can all cause the dishwasher backing up into sink.

In this case, it is best to consult a professional plumber or an appliance repair technician to diagnose and fix the problem.

Because reinstalling the device require expert knowledge.

How to Prevent Dishwasher Backing up into Sink

We have added these few precaution points that help you to prevent your dishwasher from backing up into the sink. Have a look.

  1. Run hot water in the sink for a few seconds before starting the dishwasher to ensure the drain is clear.
  2. Scrap large food particles and debris off dishes before placing them in the dishwasher.
  3. Use a high-quality dishwasher detergent and follow the manufacturer’s recommended dosage.
  4. Avoid overloading the dishwasher, which can prevent proper water drainage and cause backups.
  5. Check the dishwasher’s air gap regularly and clean it if necessary to prevent clogs.
  6. Inspect and clean the dishwasher’s filter regularly to ensure proper drainage.
  7. Run the garbage disposal before starting the dishwasher to prevent blockages in the drain.
  8. Avoid pouring grease or oil down the drain, as this can cause clogs and backups.
  9. Use a dishwasher cleaner on a regular basis to remove buildup and maintain proper dishwasher function.

Frequently Asked Questions

What should I do if the clog is beyond my reach?

Answer: If you cannot reach the clog, you should call a professional plumber or appliance repair technician. They have specialized tools and knowledge to fix the issue safely and effectively.

How do I know my dishwasher is properly installed?

Answer: You can check the installation manual or hire a professional to inspect the installation. Signs of improper installation may include leaks, vibrations, or loud noises during operation.

What is an air gap, and why is it important?

Answer: An air gap is a small, vertical device that prevents dirty water from flowing back into the dishwasher. It allows air to flow into the dishwasher’s drain line, which prevents a vacuum from forming that could pull water back into the dishwasher.

It is essential because it prevents contaminated water from flowing back into the dishwasher and potentially causing health hazards.


Dishwasher backing up into sink is a common issue you have faced. You can solve it yourself with the proper step and the right tool. Besides this problem, your kitchen sink can also be backing up from the washing machine if it shares the same drainage system. So, don’t panic when it occurs; take time, read each step carefully and think you can do it yourself or you need professional help. That’s all for today—best of luck.

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