What is an Air Gap for a dishwasher & what happens if it overflows?

An air gap for a dishwasher is a device that prevents dirty water from the sink from flowing back into the dishwasher. It is a safety measure that helps to prevent contamination and maintain proper hygiene. The air gap is typically installed on the sink or countertop adjacent to the dishwasher and is connected to the dishwasher’s drain hose.

The air gap consists of a small cylindrical or decorative cap mounted above the sink or countertop. Underneath the cap, there is a vertical pipe or tube that connects to the dishwasher’s drain hose. The other end of the drain hose is connected to the plumbing system or garbage disposal unit.

When the dishwasher drains water, it creates a siphon effect that pulls water from the sink drain as well. The air gap prevents this by introducing a physical gap of air between the dishwasher’s drain line and the sink drain line. This gap ensures that any dirty water or contaminants in the sink drain cannot flow back into the dishwasher.

If the dishwasher is not equipped with an air gap, an alternative method to prevent backflow is to have a high loop in the dishwasher’s drain hose. The drain hose is looped up under the sink or countertop, creating a barrier that prevents water from flowing back into the dishwasher. However, an air gap is generally considered a more effective and reliable solution for preventing backflow in dishwashers.

If your dishwasher air gap overflows, it can be a sign of a plumbing issue or a clogged drain. Here are some steps you can take to address the problem:

  1. Turn off the dishwasher: Start by turning off the dishwasher to prevent any further water from overflowing.
  2. Clean the air gap: The air gap is usually located on the countertop or sink next to the faucet. Remove the top cap of the air gap and check for any debris or blockages. Use a brush or toothpick to clean out any buildup that may be causing the overflow.
  3. Check the drain hose: Ensure that the drain hose connected to the dishwasher is not kinked or obstructed. Straighten out any kinks and clear any clogs if present.
  4. Inspect the garbage disposal: If your dishwasher drain is connected to the garbage disposal, make sure it is not clogged. Run water through the disposal to check if it drains properly. If it’s clogged, you may need to clear it using appropriate methods or seek professional help.
  5. Clean the dishwasher filter: Depending on your dishwasher model, there may be a filter that needs cleaning. Refer to the dishwasher’s manual to locate and clean the filter. A clogged filter can lead to drainage issues.
  6. Check the plumbing vent: A blocked plumbing vent can cause water to back up and overflow from the air gap. If you suspect this is the issue, you may need to contact a professional plumber to inspect and clear the vent.
  7. Call a professional: If you’ve tried the above steps and the air gap continues to overflow, it’s recommended to contact a professional plumber. They have the expertise to identify and resolve complex plumbing issues.

Remember, if you’re not comfortable with plumbing work or unsure about any step, it’s always best to seek professional assistance to avoid potential damage or injury.