You load the dishwasher, run a cycle, and return to standing water in the tub. That means water did not leave the appliance the way that model is supposed to drain. The cause might be a clogged filter, a sink-side blockage, a pump, or a control. This page does not rank those by frequency.
Keep owner steps to what the exact owner’s manual supports. Do not pull the dishwasher, disconnect the drain hose, or drive out a disposal knockout with a hammer.
Why a dishwasher won’t drain
After wash and rinse, a drain pump is supposed to move water through a hose into the home plumbing, often at a disposal inlet or an air gap. A blockage, a kink you cannot safely inspect, a failed pump, a stuck check valve, or a control that never calls for drain can all leave water in the tub.
Understanding those possible points helps you describe the job. It does not tell you which part failed.
Check the filter and the visible sink path
The dishwasher filter
If your manual shows a removable filter in the tub, remove the bottom rack, unlock the filter as written, and rinse debris. Reinstall it so it seats correctly. This often restores draining when the filter was the restriction. It is not a complete diagnosis.
What you can see under the sink
Look at the air gap cover on the counter, if you have one, and at the visible hose connection to the disposal or drain. Remove the air-gap cap if the manual or fixture design allows and clear debris you can see. Do not disconnect hoses under the sink unless you are prepared for water and you are following that plumbing’s instructions.
Do not slide the dishwasher out to chase a hidden kink. If the hose is not visible without moving the appliance, leave that inspection to the technician.
Drain pump, check valve, and knockout work stay with the technician
Accessing the drain pump or check valve usually means electrical connections and water lines. Replacing those parts is technician work.
If a new disposal was installed and the dishwasher still holds water, the inlet knockout on some disposals may still be in place. Checking or removing it can involve disconnecting the hose and striking the plug. That is not an owner step from this page. Tell the matched pro the disposal is new and let them confirm.
Frequently asked questions
Why is there standing water in the bottom of my dishwasher?
Possible causes include a clogged filter, a restricted sink-side drain path, a pump or check-valve problem, or a control that is not calling for drain. Start with the filter if the manual supports removing it.
What is the dishwasher knockout plug and could it be blocking my drain?
Some disposals ship with a plug in the dishwasher inlet. If that plug is still in place, the dishwasher cannot drain into the disposal. Confirming it can require hose disconnection. Ask the technician if the disposal was recently replaced.
What does a dishwasher check valve do and how does it fail?
A check valve is meant to let water out and limit backflow. Debris can keep it from moving as designed. Testing it usually requires access behind or under the unit.
When does a dishwasher drainage problem need a professional?
Request a technician when the manual-approved filter cleaning and visible sink or air-gap checks are done and water still remains, or when the next step would be moving the appliance or opening the pump.
When to call us
Repair Pro San Diego matches you with independent dishwasher repair technicians. We do not promise a one-visit repair. Leave the brand, model if known, and whether the filter is already cleaned. Call (858) 988-7787 to leave a voicemail requesting a match.