This device prevents the backflow of contaminated water from a washing machine’s drain hose back into the potable water supply. It achieves this by creating an air gap or by using a mechanical valve that only allows water to flow in one direction. A common example is the air gap fitting installed above a sink, or the break built into a standpipe.
Preventing cross-contamination of the water supply is crucial for public health. Backflow can occur due to pressure changes in the plumbing system, such as during a water main break. Without this protective measure, wastewater containing detergents, dirt, and potentially harmful bacteria could be siphoned back into the drinking water system. Regulations mandating these safeguards have been in place for decades to protect consumers.
