Most Frequent Causes for Dishwasher not draining
1.
The drain pump uses an impeller to force water through the drain hose. If the drain pump motor is not working, the dishwasher won’t drain.
2.
Over time, the drain valve can get clogged with debris. To ensure that water can flow through the drain valve, clean out the valve. If the drain valve is clear of debris but it still won’t actuate, replace it. Drain valves are not repairable—if the drain valve is defective, you must replace it.
3.
Clogged or Improperly Installed Garbage Disposer
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.