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My dishwasher runs and drains fine. But later (hours later), there will be standing water in it. Sometimes a little, sometimes a lot, enough to flow out onto the floor. I noticed we don't have a high loop in our line. But I feel like lacking the high loop would cause water backup immediately. Not hours later. Am I wrong in this assumption? Could my issue of the washer slowly filling up with dirty water be caused by not having this high loop?
Thanks
Not having a high loop in the drain line could be causing this issue. I'm guessing that your drain connects into your disposal. In that situation if you don't have a high loop when you run your disposal or empty water from the sink on the disposal side it could back up into the dishwasher.
It's easy enough to set up a high loop if there is enough slack in the drain line. Simply loop it up as high as possible. Be careful not to kink it. You can attach it to the inside of the cabinet wall or under the countertop with a clip or zip tie.
Some local codes require the installation of an air gap vent on dw drain lines for the above reason. You might want to check. If one is required it would be a good idea to have one installed. That will solve your problem.
If the dishwasher drain is lower than other drain points, water from the sink or whatever could flow back into the dishwasher. To test this, (assuming there's a kitchen sink on the same waste line), fill the sink full & let it all drain at once. See if water flows into the dishwasher.
Note that you don't report water leaking out of the dishwasher during operation, so clearly the drain pump in the dishwasher is working properly. Now, assuming that you don't have a seriously leaky input valve on the dishwasher, my first guess above is probably right. (Obviously when the dishwasher is off, the drain pump wouldn't empty water that entered from any source whatsoever)
My assumption that you don't have a high loop is indicative that you do not have an air vent installed between the dishwasher and the drain pipe. Without the air vent which would be at the top of the "high loop", water from the sink is draining into the dishwasher. Each time you use the sink, drain water is draining into the dishwasher, slowing building up the level of water in the dishwater. It is the air vent with the "high loop" that stops the water from flowing from the sink into the dishwasher.
