Show me your irrigation system is leaking without telling me

A backflow preventer is a device that is installed in an irrigation system to prevent contaminated water from flowing back into the system. It works by only allowing water to flow in one direction, and if there is a change in pressure, such as a drop in water pressure, the device will close to prevent water from flowing back into the system. This is important because it can help to prevent the spread of disease and protect the safety of the water supply.