There are many reasons that you may find your dishwasher full of dirty dish water when you open the door expecting clean dishes. While this is not a pleasant experience most drainage problems can be fixed fairly easily although some may require a bit of mechanical experience. Before you begin troubleshooting your drainage problem you should know what type of dishwasher you have and how old it is. Having a user’s manual available will make the repair much easier.
Most dishwashers drain into the plumbing system for the kitchen sink and the water will go through the garbage disposal first if one is installed. Your dishwasher will not be able to drain through the disposal or sink line if either is clogged. Check for and remove any clogs in these areas first. If this step does not solve your problem you should disconnect the drain hose coming from the dishwasher where it meets the kitchen plumbing. Once you have disconnected it check to see if this drain line is blocked. Even a dishwasher that does not require pre-rinsing food particles can end up with particles clogging the line.
As a note: If you have just installed a new garbage disposer make sure that you removed the knock out plug before the dishwasher drain line was connected. Garbage disposers are sold to be used with or without a dishwasher and they come with a removable plug to prevent leakage if no dishwasher is connected. The plug should be easy to knock out but needs to be removed completely to allow for proper drainage.
If all of your drain lines are free from any blockage you should check the dishwasher basket. You can determine the location of the dishwasher basket by using your owner’s manual. If you do not have a manual you may be able to look up a diagram for your model on the Internet. If food debris are visible when you remove the basket you can most likely solve your drainage problem with a simple cleaning. Follow any instructions from your manual and use care when cleaning this area to avoid damaging any parts.
Depending on the age and use of your dishwasher you might run into other reasons for a drainage problem. If your dishwasher is still under warranty you should not take any further actions as you could end up voiding your warranty. If your dishwasher is not under a warranty but you are not mechanically inclined it would be best to call a professional repair person.
Drainage issues can come from mechanical problems. Motors, pumps, drain valves, belts, and timers can malfunction. Your problem may even be a door latch that is not correctly making contact. These repairs can be made if you have a diagram available and the ability to obtain parts. You can listen to the motor or pump to determine if there are any unusual noises. Troubleshooting and replacing defective parts is not difficult if you have the skills but take the age of the unit into consideration. An old dishwasher may be a better candidate for replacement than for repair. Once a unit has reached a point of needing expensive replacement parts a new unit may be the better choice.