A plumber is installing a new residential kitchen dishwasher. The manufacturer's instructions require that the dishwasher drain hose connect to an air gap device on the countertop. What is the primary function of this air gap device?
- ATo filter food particles from the drain water before it enters the garbage disposal.
- BTo increase the water pressure in the dishwasher for more effective cleaning.
- CTo provide a convenient access point for adding detergent during the wash cycle.
- DTo create a vacuum break that prevents back-siphonage of dirty dishwater into the potable water supply.
Show answer & explanationAnswer & explanation
Correct answer: D. To create a vacuum break that prevents back-siphonage of dirty dishwater into the potable water supply.
The primary function of a dishwasher air gap is to create a physical separation (an air gap) between the dishwasher's drain hose and the plumbing drain system. This prevents any dirty water or contaminants from the drain from being siphoned back into the dishwasher and potentially into the potable water supply, especially during negative pressure events.
Why the other options are wrong
- A. While some large debris might be caught, the air gap is not a filter for food particles.
- B. The air gap affects drainage, not the incoming water pressure for cleaning.
- C. Detergent is added directly to the dishwasher's dispenser, not through the air gap device.
Dishwasher Air Gap Function
A dishwasher air gap is a backflow prevention device installed on the countertop, creating a physical air break between the dishwasher's drain hose and the dwelling's drain system, preventing dirty drain water from siphoning back into the potable water supply.
- Prevents back-siphonage.
- Protects potable water.
- Required by many plumbing codes.
Memory trick: Air gap's high, keeps dirty water from getting nigh.