Dishwasher Not Draining? 7 Things to Check Before Calling a Repairman
Why Won't My Dishwasher Drain?
Opening your dishwasher to find a pool of dirty water at the bottom is frustrating, but it's a problem most homeowners can solve themselves. Before you schedule a costly service call, check these seven common causes of a dishwasher that won't drain.
1. Clogged Filter or Drain Basket
Most modern dishwashers have a removable filter at the bottom of the tub. Food particles, glass shards, and debris can clog this filter, preventing water from draining. Remove the filter (usually by twisting it counterclockwise), clean it under running water with a soft brush, and replace it. This should be done monthly for optimal performance.
2. Blocked Drain Hose
The drain hose connects your dishwasher to the garbage disposal or sink drain. It can become kinked, clogged, or improperly routed. Pull the dishwasher out and inspect the hose for kinks. You can disconnect it and blow through it to check for clogs. Make sure it has a high loop under the counter to prevent backflow.
3. Garbage Disposal Knockout Plug
If you recently installed a new garbage disposal, the knockout plug inside the disposal's dishwasher inlet may not have been removed. This is one of the most commonly missed steps during disposal installation. Remove it by inserting a screwdriver and tapping with a hammer.
4. Faulty Drain Pump
The drain pump pushes water out of the dishwasher through the drain hose. If the pump motor has failed, you'll often hear a humming sound during the drain cycle, or complete silence when it should be draining. Replacement drain pumps cost $30-$80 depending on the model.
5. Clogged Air Gap
If your dishwasher has an air gap (a small cylinder on the countertop or sink), it can become clogged with debris. Remove the cap, clean out any buildup, and check that water flows freely through it.
6. Faulty Check Valve
The check valve prevents drained water from flowing back into the dishwasher. If it's stuck closed or clogged, water can't drain out. It's usually located near the drain pump and can be cleaned or replaced.
7. Control Board Issue
In rare cases, the electronic control board may not be sending the signal to activate the drain pump. If you've checked everything else, the control board may need to be tested or replaced. This is typically a job for a professional.
Prevention Tips
- Scrape food off dishes before loading (no need to pre-rinse)
- Clean the filter monthly
- Run the garbage disposal before starting the dishwasher
- Use the right amount of detergent
- Run hot water in the sink before starting a cycle
Find Dishwasher Replacement Parts
Need a new drain pump, filter, or check valve? Search your dishwasher's model number at PartsDiscount.com to find the exact part you need.