There are a few different methods of backflow prevention that homeowners can choose from.
- Air gaps – This is probably the simplest backflow preventer. It is often used in dishwashers that drain into the kitchen sink. You probably have a small, rounded dome on your kitchen sink that has slits in it—this is where the air gap is. When the dishwasher drains, it pushes dirty water through a pipe and up to that dome. Inside the dome, the pipe is cut so that the dirty water falls out and then immediately caught by a drain. If the flow of water were reversed it would overflow out of that dome but not get sucked back into the dishwasher because of the air gap.
- Valve assembly – Another type of backflow prevention device is a check valve assembly. This component is often installed at your water main and contains a series of valves that allow water to only flow one direction through it. If there is backflow, the check valve will block it to keep your water supply pure.