The part(s) or condition(s) listed below for the symptom Dishwasher not draining are ordered from most likely to least likely to occur. Check or test each item, starting with the items at the top of the page.
The motor drives an impeller to force water out of the drain hose. If the motor runs during the drain cycle, check for a blockage in the drain line. If the motor won't run during the drain cycle or if it just hums when it should be running, the pump and motor assembly might need to be replaced.
If the garbage disposer was installed recently, the drain plug may not have been removed. All garbage disposers are sold with a solid plug in the drain tube. If the dishwasher is not connected to the garbage disposer, the plug must remain in the drain tube. However, if the dishwasher is connected to the garbage disposer, the plug must be removed. If the garbage disposer wasn't replaced recently, it is possible that the disposer is clogged. Remove the dishwasher drain hose from the disposer and clean out both the fitting on the disposer and the end of the drain hose. These are the most common places to find an obstruction if the dishwasher won't drain.
The drain hose might be clogged. To unclog the drain hose, remove the drain hose from both the dishwasher and the sink drain and clean it out. The drain hose is most commonly clogged near the garbage disposer or dishwasher drain branch tailpiece.