Dishwasher problem

Just moved in to a two-year old apartment condo as a retired person. My wife and I hardly use our dishwasher, only when we have company, about twice a month. We noticed the inside bottom of the dishwasher having dirty water, perhaps a quarter of an inch high, during the time it is idle. What is causing this?

Note: The unit has a connection to the garburator just above the drain of the garburator.

Thanks in advance for any response.

If the drain hose does not connect through an air gap on top of the sink, or , as an alternative it should be looped very high under the counter top and then down to the disposer. If you don't have one of these arrangements, then dirty water slogging around in the sink and disposer can gravitate back to the dishwasher.

Also, the DW always has a little residual water in the bottom, and this could go stale. I would recommend running a rinse cycle at least once a week, with a little detergent or even just s cup of white vinegar.....just to keep it fresh.