How To Fix a Dishwasher That Won’t Drain

The dishwasher has come a long way from the introduction of this time and energy saving machine in 1886. From the initial human powered water pressure to today’s latest bluetooth feature, dishwashers have become a fixture in almost every home. Regardless, a dishwasher that isn’t draining can be extremely frustrating. What steps should you take before calling in the cavalry?

Step 1: Clean the Dishwasher Filter

Usually found in the lowest section of the bottom of the appliance, the dishwater filter is under the bottom dish rack. Some filters may be comprised of two parts, so it would be best for you to check with the manufacturer’s manual for a description of how to remove the filter safely. 

Once out, take it to the sink to rinse and scrub with warm water and a little dish soap to remove anything that is adhering to the filter. After you have brushed and washed the filter clean, rinse it completely to get rid of any leftover dish soap. Let the filter dry fully before reinserting the filter according to the manufacturer’s instructions.

Step 2: Check for Visible Blockages

Visible blockages could occur in several places in a dishwasher. Most commonly, the filter and the drain basket may filter and catch pieces of food that accumulates. After cleaning the filter, check the drain basket. If it is removable, take out the basket and clean it with water and a brush. 

Before replacing the basket, remove the drain hose from the drain at the sink or garbage disposal. Check both ends of the hose for blockages, and then check the hose for any visible damage that might be a cause for impeding drainage. If any problems are found, clean (or replace) the hose, and flush it with water to clean it as much as possible. These basic checks are often the first move when figuring out how to fix a dishwasher that won’t drain without professional help.

Step 3: Run a Cleaning Cycle

Before running a cleaning cycle, replace the drain hose, but leave the filter and basket removed. Place the specified amount of dishwasher cleanser in the machine according to the product instructions. Put your dishwasher through a normal, hot cycle to hopefully clean out any debris. 

If you are not interested in using a commercial dishwasher cleaning product, a cup of white vinegar on the top inside rack can be effective. Do a normal, hot cycle for cleaning. Optionally, after the vinegar cycle, scatter a cup of baking soda across the bottom and go through a short, hot cycle for further cleaning. This method is also helpful when tackling persistent dishwasher water not draining problems caused by grease or food buildup.

Step 4: Inspect the Drain Hose and Garbage Disposal

A secondary inspection of the drain hose may be helpful here after the cleaning cycle to verify that it is unblocked. After that has been done, it is time to check out the garbage disposal. This is often the cause of dishwasher water not draining.

When inspecting a garbage disposal for obstructions, please remember: SAFETY FIRST! The best action is to turn off the power at the circuit breaker. Also, never put your hands in a garbage disposal even if it is turned off.  Use a flashlight to examine the disposal chamber for anything blocking drainage. If there is something clearly there, use tongs or a pair of pliers to displace or remove it. If the dishwasher water is not draining, use a clean plunger to apply suction in an effort to shift any stuck material.

If these two actions are ineffective, there should be a socket at the bottom of the disposal that can be turned. Usually, this is turned with an Allen key, and rotating the key will turn the blades inside to dislodge any material. 

Finally, check over the P-trap, or curved piping, under the sink. If that is removed to look for clogs, remember that pipes should be reattached with something similar to teflon tape to help avoid water leaks later.

Step 5: Check the Drain Pump

The drain pump is found at the bottom of the dishwasher, and it pushes water out the drain hose. It ensures that waste water is expelled and doesn’t stay in the dishwasher. 

To determine if the drain pump is malfunctioning, there are a few things to look for. After making sure that the drain hose is clear of obstructions, and the filter has been cleaned to your satisfaction, listen for any errant noises coming from the pump. Any scraping, clattering, or grating sounds could indicate that something is stuck or the pump is beginning to fail. 

Testing the pump requires the use of an ohmmeter to check electrical impedance through the pump. First, make sure that the dishwasher is disconnected from the house’s power supply. After locating and gaining access to the pump, use the ohmmeter to check for the pump’s electrical resistance. If the pump is operating properly, 160-260 ohms usually indicates that the pump is working properly. If you get a reading outside that range, then the pump will probably need to be replaced. 

Step 6: Reassemble and Test

The final step  to check if a dishwasher is not draining. After checking all requisite pipes, drains, and filters for blockages, and the pump appears to test in range, it is time to reassemble the unit for testing. Make sure that the filter is seated correctly, the drain hoses are fastened, and the pump is locked in place. Reconnect the power and put the dishwasher through a short cycle to check for drainage and to make sure that there are not any leaks.

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