3 Reasons ​​Why Your Dishwasher Won’t Drain

When your dishwasher isn’t draining, it feels like a coworker 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 and Troubleshoot Why Your Dishwasher Is Not Draining

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 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. Clogged Dishwashers

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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’re 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.

The drain line wasn’t intended to move out food; it was designed to move out water. So 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. Learn how to drain a dishwasher and see if you can remove the clog.

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.

Solution

In most cases, you'll find your drain line snaking out of the back of your dishwasher and into a drain pipe. If the line is behind the dishwasher, you may need to pull the dishwasher out from the wall to inspect it more closely. However, most lines are accessible in the area under your kitchen sink.

Disconnect the dishwasher from its power source either by unplugging the unit or switching off the breaker. Place a bucket under your pipe and open the clamp around the pipe to release the drain line. If the source of the clog does not dislodge, use a soft-bristled bottle brush to clear it manually. Leave tougher clogs for the professionals to avoid damaging the line.

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 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.

Solution

Most dishwasher drain pumps live directly below the filter basket. After turning off the power source, remove all the water from the base of the dishwasher manually and remove the top filter basket.

At this point, it's best to check your user's manual if you have it on hand. Drain pumps differ by model, but you should be able to reach them just below the filter. While wearing gloves, gently reach into the filter area and remove the pump cover. Be careful—the item blocking the pump drain could be sharp. Check the area for debris and return the pump cover according to your manual.

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.

Solution

In many cases, unclogging your dishwasher from simple grease clogs takes a few household products. Begin by disconnecting the dishwasher from its power source. After manually removing as much water as possible, remove the filter by gently unscrewing it counterclockwise and pulling it up and out.

Combine equal parts baking soda and white vinegar and pour them into the dishwasher drain. Wait about 15 minutes before flushing the drain with hot water. 

2. Garbage Disposal Problems 

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 paid for the cost to install a garbage disposal and then began experiencing drainage issues with your dishwasher, this may be the culprit.

Solution

If you suspect there was an installation error made by the original professional, you'll need to call a garbage disposal repair specialist near you. Recently installed garbage disposals may still be under warranty, especially if the issue was caused by a professional in the first place. The pro can make sure your garbage disposal drain lines properly line up with your plumbing.

On the other hand, if you DIY installed the garbage disposal, break out your user manual. Walk through the installation steps to ensure the drain line properly connects to your home's plumbing.

Clogs

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

Solution 

Many dishwashers and garbage disposals share a drain line. If grease or foreign items block the line, neither will function properly. Thankfully, unclogging a garbage disposal is a DIY job in many situations, especially if there’s simply a fibrous bit of food stuck in the works. A few methods for unclogging a garbage disposal include:

• Pouring a solution of baking soda and vinegar down your sink drain

• Resetting your garbage disposal 

• Using a small plunger to loosen the clog

• Loosening the impellers to allow the clog to pass through

3. Damaged Circuit Boards

Modern dishwashers are controlled by circuit boards usually located in the machine’s front paneling. Though designed to be sturdy, it’s a problem when they become damaged. 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 your dishwasher is between $300 and $500.

Solution

Electrical problems with your dishwasher should always be left to the professionals. Both the presence of electricity and water make this too dangerous a fix to DIY. However, a trained pro can either replace your circuit board or test for minor damage to the appliance's wiring. If your model is more than 15 years old and is having electrical issues, you'll spend an average of $970 on the cost of a new dishwasher.

Tips to Prevent Clogs in Your Dishwasher 

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

Know When to Call the Pros 

Water pooling at the bottom of your dishwasher can look frightening, but there's often an easy fix to the problem. However, if you try to remove the clog or determine the issue stems from an electrical problem, call a local dishwasher repair pro. In some cases, your warranty may even depend on it.

It’s also never a good idea to dismantle your dishwasher or the surrounding plumbing outside of checking the drain line for clogs and removing the filter at the base of the machine. Leave all complex repairs to the professionals to avoid harming yourself or the longevity of the dishwasher.

Becca Stokes contributed to this piece.