The Safe Water and Drinking Act, passed by Congress, requires backflow prevention. When the water company gives us water, they play for keeps. They don’t want that water back… like, ever. The facility owner is responsible for protecting the water outside of their facility (containment) as well as protecting the water indoors (Internal Use Valves).
Backflow prevention can be split into two categories:
Containment: These devices are used to prevent back flow inside the facility and away from the main water line. Two types of containment devices exist on the market, the double check assembly and the reduced pressure assembly. Double Check Assembly’s are generally installed in low-hazard facilities, or systems without chemical activities and non-toxic substances. The reduced pressure assembly (RPZ) includes a pressure differential relief valve that leaks when something fails with the check valve. The RPZ valve is installed in high-hazard facilities where a broken back flow device can impact human health. Examples of these facilities include hospitals and car washes.
Internal use: A wide range of devices exist to prevent backflow and backsiphonage. Generally, the selection of devices is determined by degree of hazard, piping size, location (local code) and need to test devices. Some examples of internal devices are Air Gaps, dual check valves and vacuum breakers. One of the biggest culprits of contaminated water is the garden hose. A hose bib connection vacuum breaker can be a great option for eliminating this danger.
As always, consult your local codes for accepted backflow preventers, and feel free to ask us any questions in the comments below!