Backflow Valves are an essential and fundamental way to keep your drinking water safe to use. Plumbing systems in your house, business and neighbourhood are complex. Therefore, if there is any pressure loss failure in this vast system of pipes, outside contamination can enter your water. This is important – you wouldn’t want your neighbours lawn fertilizer or a restaurant’s old dishwasher soap in your drinking water! For this reason, the City of Delta mandates that all backflow valves must be tested annually.