If your dishwasher is not draining correctly, before you call in plumber or purchase a new dishwasher, check theses three simple things. First, filters. You should be washing your filters once each week. This may be clogged and prevent your dishwasher from draining. Next check the drain line, or the waste hose. This is what carries the water to the drainage system of your home. Make sure it is not clogged, kinked or mashed. Finally, if your dishwasher is connected to the sink drain, make sure the sink drain is clear. These simple steps can save you from calling a professional.