If you have water sitting in the bottom of your dishwasher, you may first look to a blocked drainage issue. That is a good instinct, but not always the cause of pooling water. Upon your investigation, you may find water actually coming back up from the drain. What is causing this is likely a faulty check valve.
The check valve is a small part in which all drain water flows past. It is meant to close so that any drain water still in the lines cannot flow back up into the dishwasher tub. However, if it malfunctions, then the event it is meant to prevent will likely come true. Furthermore, you may find water from your sink can enter your dishwasher if this part malfunctions.
Discussing a WD24X10018 – GE Dishwasher Check Valve
How to Replace a Dishwasher Check Valve
To start this repair, turn off the power and water from your dishwasher. While you can access this part from the tub in some models, it is vastly easier to just pull the dishwasher out and make the repair from the bottom.
Removing the dishwasher from the cabinet, you will want to lay your dishwasher so you can access the drain pump underneath. Once accessed, remove the wire harnesses from the drain pump and remove the screws on the mounting bracket. Remove the clamp that secures the drain motor to the sump. You may wish to have a towel or bucket to catch any loose water.
Removing the drain pump, you will now have access to the check valve on the end that was inserted into the sump. Sometimes this part just needs to be cleaned, but it is often better to just replace it, seeing as it is such an ordeal to reach. The new check valve should slide right into the old holder.
The holder can then be reinserted and your dishwasher can be reassembled and reinstalled. This should fix your water issue.