What should I do if my dishwasher won't drain and water is standing in the tub?

If water won't pump out, check whether the air gap is clogged and clean it if needed. You should also verify that your kitchen sink is draining well, as a clogged drain may be the cause, and if the dishwasher drains into a garbage disposer, run the disposer clear. A small amount of clean water around the outlet on the tub bottom is actually normal and keeps the water seal lubricated. (Page 20)