When the danger of backflow and back-siphonage is high, and a significant hazard is possible, a backflow device known as a RPZD utilizing the reduced pressure principal is commonly used.

This principal not only utilized a double checks (valve) system but also a pressure monitored chamber between the two check valves.  That way even if the double checks valves fail, backflow is still prevented.

At City Backflow Testing, our testing is done in compliance using the USC 10^th Edition.  We mention that so you will know that your hiring experts when you are hiring City Backflow Testing.