Do Dishwashers Have to Have Air Gaps?

Air Gap

• Dishwashers are designed to operate along with your sink, using the same water lines. In order to prevent water from flowing back out of the dishwasher and potentially backing up into the sink, dishwashers use an air gap. In some cases, this air gap can become clogged and cause water to leak out of the air gap cap on top of the sink.

Operation

• When your dishwasher is operating properly, it uses the water lines to get the water it needs. The water then goes through the dishwasher's drainage system and exits the machine. However, when it leaves the appliance, it creates suction on any water that is still in the dishwasher. The air gap allows air to get into the dishwasher so water will only leave when it is supposed to. Also, if the drainage system gets clogged, the water can flow through the air gap and into the sink, instead of leaking out of the machine and onto the kitchen floor.

Air Gap Problems

• An air gap can become clogged and cause problems. If your air gap is partially clogged, you may see a white residue around the air gap cap on the sink. You can remove this cap and inspect the air gap to see if there is any residue or material clogging it. Clearing the obstruction will generally remedy the problem. If not, you may have to replace the air gap or the hoses that connect it to the machine and your sink or garbage disposal.

Other Considerations

• Some dishwashers don't have an air gap. Some machines have a "high loop" system that serves the same purpose as an air gap. A high loop system is so named because the hose that drains from the garbage disposal or sink bottom loops up higher than the sink base. This prevents water from flowing back from the dishwasher into the sink. If you're having problems with your dishwasher's drain system, you should contact a qualified appliance installer or plumber.