Why does garbage disposal backs up when dishwasher runs?

Author: Calista Cole  |  Last update: Tuesday, September 23, 2025

There are two ways garbage disposals can cause water coming back up the kitchen sink from the dishwasher. Either the garbage disposal is clogged from food debris, or it's freshly installed, and the knock pin wasn't removed.

Why does my disposal back up when I run the dishwasher?

The dishwasher drain is likely connected to the garbage disposal. This would mean that your sink drain is partially clogged. The dishwasher will pump out water at various points of the wash cycle and it is just backing up in to the sink.

How do I stop my dishwasher backflow from the garbage disposal?

Drain Hose Air Gap

Some dishwasher drain hoses use an air gap to create a section of air in the dishwasher drain line hose loop to prevent dirty sink water from flowing back into the dishwasher. It usually looks like a silver cylinder set close to the rim of the kitchen sink near the faucet closest to the dishwasher.

How do you fix a garbage disposal that backs up?

  • Turn off the garbage disposal and disconnect power.
  • Use tongs or pliers to remove any visible debris inside.
  • Insert an Allen wrench into the bottom of the disposal.
  • Rotate the wrench back and forth to dislodge the clog.
  • Reconnect power and test if the disposal drains.
  • If still clogged, repeat or use a plunger.

Why is my garbage disposal not draining while dishwasher is running?

If your garbage disposal is blocked with food or grease, then it can delay the movement of water out of the dishwasher. This causes the standing water effect. You'll want to check your garbage disposal thoroughly for food particles. Sometimes simply letting it run for a few seconds can take care of the problem.

How to Fix Backflow into Your Dishwasher | inexpensive fix to your dishwasher not draining

Is it bad to run the garbage disposal while the dishwasher is running?

Run your dishwasher AFTER using your garbage disposal. Dishwashers and garbage disposals drain into the same pipe, so using the garbage disposal beforehand will ensure the pipe is clear.

Where is the air gap on my dishwasher?

Where is the dishwasher air gap located? The dishwasher air gap is a chrome or stainless steel cylinder fitting that can be found at the back of the sink near the faucet.

Why does my garbage disposal keep binding up?

Particles of food, such as small bones, eggshells, and fruit skins, can get stuck in the blades of the disposal and cause a blockage. Accumulated grease and oils from food can also cause a blockage. If you haven't used your disposal in some time, the motor may have become seized or corroded, causing it to jam.

Why does my garbage disposal spit back up?

When the garbage disposal is backing up, the cause might be as simple as objects binding the blades inside the appliance. Or the drain that connects the disposal to the rest of the sink's drain trap assembly might be clogged. Whatever the cause, a backed-up garbage disposal is usually easy to fix.

Why is my sink backing up with no clog?

Slow drains may not always be due to clogs.

Plumbing vents, soap buildup, and garbage disposal malfunctions are among the most common culprits.

How do I fix my dishwasher backing up to the sink?

Disconnect the hose from both the dishwasher and the sink drain. Inspect the hose for any kinks or visible blockages. Run water through the hose to check for any obstructions. If you find any issues, clean the hose or replace it if necessary.

Why does my sink overflow when the dishwasher runs?

Problem: A drain clog is one of the leading culprits of a sink filling up while the dishwasher is running. Over time, debris, food particles, and grease can accumulate in the sink and dishwasher drains, restricting water flow.

Why is my disposal leaking when dishwasher runs?

In most cases, leaking garbage disposal is caused by a dishwasher drain hose that isn't correctly connected. If your dishwasher drain hose is leaking, you may be able to fix the problem by removing the hose and cleaning it out. Start by disconnecting the hose from the dishwasher and the garbage disposal.

How do you unclog a dishwasher and garbage disposal?

Steps to unclog your dishwasher drain
  1. Remove your dishes. ...
  2. Check your garbage disposal. ...
  3. Disconnect your dishwasher from power. ...
  4. Remove any standing water. ...
  5. Clean the drain. ...
  6. Check the filter. ...
  7. Clean your sink's air gap. ...
  8. Check and clean the drain hose.

Can you run the garbage disposal without water?

A common question our local plumbers get is: what happens if you run your garbage disposal without water? The answer: nothing good.

How to fix a garbage disposal that is backing up?

You can create an effective drain cleaner easily by simply mixing equal parts baking soda and vinegar. Dump this solution down your sink drain, wait 15-30 minutes, then try to flush the back-up out with hot water, running the tap for at least a minute.

Is it okay to put coffee grounds down the garbage disposal?

Coffee grounds won't hurt your disposal, per se. They'll actually go down easy and even smell good doing it. But once they get further, they can accumulate like they would in a coffee filter, creating an obstruction in the pipes. Coffee grounds are best disposed of in the compost pile or the trash.

Should you use drano in a garbage disposal?

PLEASE NOTE: Drano® Professional Strength Crystals Clog Remover is NOT safe for use in garbage disposals.

Why is my garbage disposal spitting stuff back up?

Stuck food in your drain and pipes is the most common reason garbage disposals get backed up, and it's one of the easiest problems to fix. To keep your receptacle in good condition, try not to put all your meals down your sink.

How long should a garbage disposal last?

How Many Years Do Most Garbage Disposals Last? Most modern garbage disposals will last anywhere from 8 to 15 years. An average household with four or five family members can expect to replace their disposal roughly every 12 years if properly maintained.

Why does my garbage disposal keep jamming up?

A leading cause of a disposal jam is overwhelming it with too much food all at once. This can cause a damaging accumulation over time. Blades can even become damaged. The rule of thumb is to only put tiny bits down your disposal at a time to prevent jams.

What is a hidden air gap for dishwasher?

The easiest way to hide a dishwasher air gap is by installing an air gap cover. These covers are easy to install and visually appealing. Another option to conceal a dishwasher air gap is to install a countertop overlay.

Why do I have water pouring out of my air gap when I use my dishwasher?

Clogs. The most likely cause of a dishwasher air gap leaking is a clog. Most of the time, you can make this dishwasher repair yourself.

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