Recommended Practice for Backflow Prevention and Cross-Connection Control, 3rd Ed. (M14)

Book excerpt: Cross-connection control is one of the most important barriers in the multiple-barrier approach drinking water suppliers use to protect public health. Contamination of a drinking water distribution system through a cross-connection often results in immediate adverse health effects - illness or even death. This Manual provides a total cross-connection control program for your water system. The manual explains how cross-connections and backflow can occur and tells you how to choose, install, and maintain backflow prevention devices. You ll learn the water purveyor s legal responsibilities, as well as the customer s responsibilities in backflow prevention. The manual covers risk assessment, types of programs to consider, and program administration. Until the cross connection control program is fully developed, the water purveyor is at maximum risk of potential liability. This Manual also explains the hydraulics of backflow, the two types of backflow backsiphonage and backpressure, and the conditions that can cause backflow and a potential cross-connection (such as a water main break). You ll get expert guidance in selecting and installing backflow prevention equipment andl learn the 10 main types of backflow prevention devices or assemblies (yes, they are different), and the relative effectiveness of each type against backsiphonage, backpressure, and low and high hazards. The manual describes each device or assembly, its application in a water system, installation requirements. Detailed assembly test procedures are included for the different types of devices and assemblies. This Manual recommends backflow prevention equipment for installation in the water distribution system, as well as raw water-storage reservoirs, chemical feed pumps and injectors, filters, surface washers, saturators and dry chemical solution tanks, sampling lines, hose bib connections, and membrane systems.