Yes, an irrigation system is required to have a backflow device if it is connected to the public water systems. An irrigation backflow device is a mechanical device that is installed in an irrigation system to protect the water supply from contamination. Backflow devices allow water to flow in one direction only, preventing contaminated water from flowing back into the public water supply. All irrigation systems in Nevada are required to have a backflow device, and these devices must be tested annually by a certified back.