3 Reasons ​​Why Your Dishwasher Won’t Drain

Becca Stokes
Written by Becca Stokes
Updated August 18, 2021
 Unloading dishwasher in pretty kitchen
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Know why clogs happen to prevent future problems

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When your dishwasher won’t drain, it’s like a co-worker calling in sick. You’re suddenly saddled with more work, and you’re desperate for them to get well. But understanding what causes these problems can not only save your appliance, but keep it from breaking in the future, too. 

Assess Your Machine

Before you contact a local dishwasher repair professional to address your broken dishwasher, do a quick visual inspection of the machine.

  • Identify the drain line. Are there any kinks or twists that could be blocking water?

  • Is the drain pump properly in place?

  • Is the spinning arm operational?

Make sure you examine your dishwasher’s drain basket, located near the dishwasher’s base. Emptying it and cleaning it regularly is a good way to prevent blockages.

  • Examine the bottom of your dishwasher. Is there standing water or noticeable food debris?

  • Does the water drain once you’ve removed the food?

  • Does the dishwasher give off a bad smell?

Even if you can’t crack the case yourself, being able to answer these questions before a pro has to ask them will be really helpful. 

1. Clogs

Kitchen interior with stainless steel dishwasher
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The primary reason dishwashers stop draining is because one or more of their components is clogged. When a clog forms, water can’t move freely throughout the machine the way it was designed to.

Drain Line Clogs

Your dishwasher’s drain line (also known as its drain hose) is the tube responsible for moving the water out of the appliance at the end of every wash cycle. If you are not rinsing excess food off your dishes before you put them inside your dishwasher, that debris is also being flushed out via the drain line.

But the drain line wasn’t intended to move out food; it was designed to move out water. When food passes through the tube, it gathers on the sides and builds up until a clog is formed, leaving the dishwasher unable to drain. 

Another cause of clogging: If you live in a location where the temperature regularly falls below freezing and your drain lines are in an exterior wall, they may freeze. This makes drainage impossible.

Drain Pump Clogs

The drain pump is another component of your dishwasher that can become clogged with food debris. The drain pump is responsible for moving the water supplied to the dishwasher throughout its rotating arm and nozzles. This kind of clog doesn’t just cause drainage problems—they make your dishwasher less effective. The national average cost to repair a dishwasher by removing a clog from a drain pump or drain line is $200. Save yourself some cash by scraping and rinsing your dishes well before they go into the machine.

Grease Clogs

Grease is one of the biggest sources of dishwasher woes. When it builds up inside of your appliance, it can stop the machine from draining and cause additional problems. 

For example, when grease covers the springs inside your dishwasher it puts them out of commission. Without these springs moving debris away, bigger clogs form—and faster.

2. Garbage Disposals

Sometimes plumbers have to look past the dishwasher to find the real problem. Garbage disposals are actually a common culprit when it comes to external factors affecting a dishwasher’s ability to drain properly. 

Installation

Often, errors in installation can lead to garbage disposals draining into the dishwasher. If you recently had a garbage disposal installed and then began experiencing drainage issues with your dishwasher, this may be the culprit.

Clogs

Just like dishwashers, clogs are a common problem in garbage disposals, especially from grease build-up. This can cause the garbage disposal to back up, which can stop your dishwasher from draining.

3. Damaged Circuit Boards

Modern dishwashers are controlled by circuit boards usually located in the machine’s front paneling. Though designed to be sturdy, when they become damaged, it’s a problem. Damaged circuit boards can make it impossible for your dishwasher to know that it needs to drain, leaving you with a mess on your hands. The average cost to replace a circuit board inside of your dishwasher is between $300 and $500.

Clog Prevention

Stop grease from building up inside of your garbage disposal and your dishwasher by picking the right detergent and by regularly deep-cleaning your dishwasher.

  • Use cleaning tablets that clean your drain line and pump, in addition to your dishes

  • Install an air gap in your dishwasher. This will help if your dishwasher backs up due to clogs. The air gap is installed a few inches above the spigot of your sink and, when backups and blockages occur, redirects wastewater.

  • The main sewage line can back up rain sewage from the whole neighborhood into your home. If you’ve noticed warning signs that the main sewage line is clogged, it can affect your entire home.

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