The purpose of an air gap on a dishwasher or washing machine drain hose is to prevent backflow of wastewater into the appliance and ensure proper drainage. It acts as a physical barrier between the appliance's drain hose and the household plumbing system.
An air gap consists of a vertical pipe or device that is typically installed on the countertop or sink near the dishwasher or washing machine. The appliance's drain hose is connected to one end of the air gap, while the other end is connected to the household plumbing system or drainpipe.
When the appliance drains water, the wastewater flows through the drain hose and into the air gap. The vertical height of the air gap creates a gap of air between the wastewater and the household plumbing. This air gap breaks the siphoning action that can occur when water flows rapidly through the drain hose, preventing any contaminated water from being pulled back into the appliance.
The presence of the air gap ensures that there is no cross-contamination between the wastewater and the appliance. It helps to prevent potential contamination of clean dishes or clothes and protects against the risk of backflow that may occur due to a blockage or backup in the plumbing system.
Air gaps are typically required by building codes in many regions as a safety measure to prevent backflow and maintain proper hygiene standards. Installing and maintaining an air gap is an important aspect of ensuring the safe and effective operation of dishwashers and washing machines.