Dishwasher Not Draining: Safe Checks

Everything below is a power-off inspection.

Switch the dishwasher off at its breaker or unplug it before removing anything from the tub. Scoop the standing water out with a cup and a towel first, so you can see the sump rather than work blind. Do not run another cycle to push the water through before looking.

Most modern dishwashers have a user-serviceable filter in the floor of the tub.

Twist out the cylindrical filter and rinse it under a tap; food, labels, and glass fragments collect there and will stop drainage completely. Check the sump underneath for debris while the filter is out. Manufacturers treat this as routine owner maintenance rather than repair, and it resolves a large share of drainage complaints.

A new garbage disposal ships with the dishwasher inlet sealed.

If the dishwasher drains into a garbage disposal that was recently installed, the knockout plug in the disposal inlet may never have been removed, which leaves the drain hose connected to a sealed port. Run the disposal itself as well: one holding food waste can block the shared drain path.

Drainage relies on a high loop or an air-gap fitting to stop backflow.

The drain hose should rise to a high loop under the counter, or connect through the air-gap fitting on the sink deck where one is installed. Unscrew the air-gap cap and clear any debris inside it. Check that the hose is not kinked or crushed behind the machine, which happens after a dishwasher has been pulled out for other work.

Pumps, wiring, and water under the cabinet are service work.

If the filter, disposal, air gap, and hose are all clear and the water stays, the drain pump or its control is the likely cause, and that is a service call. Water on the floor, a burning smell, or a machine that trips a breaker means leave it switched off and call a professional. A leak that soaked cabinetry is also a moisture problem worth addressing before it becomes a mould problem.