Dishwasher and Sink Not Draining

“Are you struggling with a dishwasher and sink that won’t drain? Don’t let standing water become a daily inconvenience. Read on for solutions to this frustrating problem.”

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This article discusses possible causes for a dishwasher and sink not draining properly. For dishwashers, issues can include a clogged or blocked drain hose, malfunctioning drain pump, faulty float switch, or blocked air gap. Sink drainage problems may be caused by a clogged or blocked drain pipe, broken garbage disposal unit, plumbing system issues such as leaks or damage, or improper installation of pipes/fixtures. A list of possible causes is provided along with troubleshooting tips.

Possible Causes of a Dishwasher and Sink Not Draining Properly


A dishwasher that won’t drain properly can be caused by a variety of issues. One common cause is a clogged or blocked drain hose. This can happen if food particles or other debris get caught in the hose over time. Another possible cause is a malfunctioning drain pump, which may not be working efficiently or at all.

Another potential issue with dishwashers is a faulty float switch. The float switch is responsible for regulating the water level in the dishwasher, and if it’s not working correctly, the dishwasher may not drain properly. Finally, a blocked air gap can also cause drainage problems in a dishwasher. The air gap is located on the sink next to the faucet and helps prevent backflow from the dishwasher into the sink.


A sink that won’t drain properly can also have several causes. One common issue is a clogged or blocked drain pipe. This can happen if food particles, grease, or other debris accumulate in the pipe over time. Another possible issue is a broken garbage disposal unit, which can cause blockages and prevent water from draining properly.

In some cases, sink drainage problems may be caused by issues with the plumbing system itself. For example, if there are leaks in the pipes or if they’re corroded or damaged, this can affect drainage performance. Additionally, improper installation of pipes or fixtures can also lead to drainage problems.

List of Possible Causes:

  • Clogged/blocked drain hose
  • Malfunctioning drain pump
  • Faulty float switch
  • Blocked air gap
  • Clogged/blocked drain pipe
  • Broken garbage disposal unit
  • Leaking or damaged pipes
  • Improperly installed pipes/fixtures

Troubleshooting Tips for a Dishwasher and Sink Not Draining

If your dishwasher and sink are not draining properly, there are several troubleshooting tips you can try before calling a professional plumber. First, check the drain hose to make sure it’s not clogged or blocked. If it is, remove any debris and see if this solves the problem.

If the drain hose is clear but the dishwasher still won’t drain, check the drain pump to make sure it’s working correctly. You can do this by removing the pump and checking for any blockages or damage. If everything looks okay, try running the dishwasher again to see if it drains properly.

For sink drainage problems, start by checking the garbage disposal unit. Make sure it’s turned on and working correctly. If it’s not, try resetting it by pushing the reset button on the bottom of the unit. If this doesn’t work, you may need to replace the unit entirely.

If neither of these solutions works, try using a plunger to clear any blockages in the drain pipe. Fill up the sink with water and use a plunger to create suction and dislodge any debris that may be blocking the pipe.

List of Troubleshooting Tips:

  • Check for clogged/blocked drain hose
  • Check drain pump for blockages/damage
  • Ensure garbage disposal unit is turned on/working correctly
  • Reset garbage disposal unit if necessary
  • Use plunger to clear blockages in drain pipe

DIY Solutions to Fix a Dishwasher and Sink That Won’t Drain

If you’re comfortable with DIY projects, there are several solutions you can try to fix a dishwasher and sink that won’t drain. For example, if the drain hose is clogged or blocked, you can remove it and clean it out yourself. Similarly, if the garbage disposal unit is broken, you can replace it yourself by purchasing a new unit and following the manufacturer’s instructions.

If the problem is more complex, such as a malfunctioning drain pump or faulty float switch, you may need to purchase replacement parts and install them yourself. This requires some basic plumbing knowledge and tools, so make sure you feel confident before attempting this type of repair.

List of DIY Solutions:

  • Clean out clogged/blocked drain hose
  • Replace broken garbage disposal unit
  • Purchase replacement parts for malfunctioning components (e.g., drain pump, float switch) and install them yourself

When to Call a Professional Plumber for Help with Dishwasher and Sink Drainage Problems

If you’ve tried troubleshooting tips and DIY solutions but your dishwasher and sink still won’t drain properly, it’s time to call in a professional plumber. A plumber will have the expertise and tools necessary to diagnose the problem accurately and recommend appropriate solutions.

In addition, certain issues should always be handled by a professional plumber. For example, if there are leaks in your pipes or if they’re corroded or damaged, this requires specialized knowledge to fix safely. Similarly, installing new pipes or fixtures should always be done by a licensed plumber to ensure proper installation.

List of Issues Requiring Professional Help:

  • Leaks in pipes
  • Corroded or damaged pipes
  • New pipe/fixture installation
  • Complex issues that require specialized knowledge/tools (e.g., replacing drain pump, fixing faulty float switch)

Steps to Prevent Future Issues with Dishwasher and Sink Drainage

To prevent future issues with dishwasher and sink drainage, there are several steps you can take. First, make sure to properly dispose of food waste and grease by scraping plates and pans into the trash before washing them. This helps prevent blockages in the drain hose or pipe.

In addition, avoid pouring oils or fats down the drain, as these can solidify and cause blockages over time. Finally, consider scheduling regular maintenance checks with a professional plumber to catch any potential issues before they become major problems.

List of Prevention Steps:

  • Properly dispose of food waste/grease by scraping into trash
  • Avoid pouring oils/fats down drain
  • Schedule regular maintenance checks with professional plumber

In conclusion, a dishwasher and sink not draining can be caused by various factors such as clogs, faulty parts, or improper installation. It is important to identify and address the root cause promptly to prevent further damage and inconvenience. Seeking professional help may also be necessary in some cases.

Frequently Asked Questions

Why is my dishwasher and sink not draining properly?
If your dishwasher isn’t draining, examine the connection points in the plumbing. Verify that the drain hose is properly attached to the sink or garbage disposal and free of any leftover food or debris. Additionally, inspect the hose clamp and drain solenoid.

Why is my sink and dishwasher full of water?
If the drain is blocked, it can cause water to flow backward into the dishwasher due to pressure in the pipe. To fix this issue, you can attempt to remove the P-trap located under the sink and clear out any debris. Remember to place a bucket to catch the water before doing so.

Why is my sink not draining when there is no clog?
In case you have ruled out a clogged sink but still experience slow draining, it is probable that the problem is with the plumbing vent. Plumbing vents are usually situated on the roof of a house.

Why is my sink backed up after running the dishwasher?
If there is standing water in your dishwasher, it means that it is not draining properly. You should inspect the drain and drain hose for any blockages that may be causing the problem. Additionally, you should be cautious about the amount of dishwashing detergent you use as excess residue can accumulate and lead to a clog. This advice was given on March 20, 2018.

Can I put Drano in my dishwasher?
To be clear, it is not recommended to use Drano in a dishwasher. This is due to the strong chemicals in Drano that can harm the plastic components of the appliance and potentially contaminate your dishes.

Can a plunger unclog a dishwasher?
In case your sink is draining slowly and your dishwasher waste is connected to it, this may be where the blockage is. You can attempt to clear the clog by pouring boiling water down the sink or using a plunger. It is possible that the blockage is further along the dishwasher waste hose.

Charlie Thomson is Appliance Mastery's expert on laundry appliances. With a degree in mechanical engineering and over 8 years of experience in the appliance repair industry, Charlie is a go-to resource for homeowners who want to tackle common issues with their washing machines, dryers, and dishwashers.

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