A clogged air gap can cause a dishwasher not to drain. There are, however, other potential issues that can lead to improper drainage. For example, if you have attached the air gap to a garbage disposal and forgotten to remove the knockout plug, wastewater may backflow into the dishwasher. Check that the air gap is installed properly, and then look for clogs in the air gap and dishwasher filters. 

The drain pump will naturally make a standard operational and draining sound several times throughout your dishwasher cycle. If you hear abnormally loud sounds like scraping, grinding, or clicking, you may have food debris or a piece of glass stuck in your drain filter. Avoid dishwasher repair by always scraping food off your dishes and loading the racks correctly.

Yes, a dishwasher needs an air gap to prevent backflow. Additionally, in many locations, air gaps or another measure to prevent backflow are required for building code compliance. There are alternatives to an air gap, like a Studor vent or a loop and trap design, but an air gap is the simplest and most popular solution.  

The answer is a resounding yes, as dishwashers save significant water and energy compared to washing dishes by hand. The difference is so drastic in fact that those who use energy-efficient dishwashers can expect savings of over $450 per year. This is because dishwashers use less water, they wash at a higher temperature than a hand rinse, and you don’t need to rinse them after washing. New dishwashers use around 4 gallons per load, whereas washing by hand can use up to 2 gallons per minute.