What exactly is “backflow” and why worry about it?
The official law of backflow prevention goes back a long way. It was 1973 when the Environmental Protection Agency established the “Safe Drinking Water Act” as a means of protecting public water systems from harmful contaminants and pollutants that may enter the water system through cross-connections, backflow, and back-siphonage.
Backflow prevention is important because we assume that when we turn on the water tap, we have safe drinking water. This is a luxury we enjoy, but not without very strong regulations and considerable expenses. Our drinking water is among the safest in the world. Water protection and conservation requires the effort and cooperation of everyone.
Because of this, customers who have cross connections are required to have backflow valves in place to prevent contaminants from entering the public water system through their individual plumbing system. Backflow assemblies are devices installed on cross-connections to prevent water from flowing backwards into public water systems.
Drinking water normally flows in one direction (from the meter to the house), although under certain circumstances it can flow in the opposite direction or “backflow.” A backflow incident can happen at any time. All that is needed is a water pressure drop in the public water system main line, creating a “vacuum” that pulls the dirty water back into the source of clean water. This is most commonly caused by fire fighting, hydrant flushing, flow testing, a water main break, or an extreme high usage of the water system. Any connection to a non potable water source not protected could be siphoned back into the public water system, which can pollute or contaminate the water system.
The most common type of backflow assembly is a double check valve assembly, which consists of two independent check valves, two resilient seated shut off valves and test cocks. To ensure they work correctly, all backflow assemblies must be tested annually (with the exception of atmospheric vacuum breakers) and properly tagged upon passing.
In addition to yearly testing, backflow preventer assemblies must also be tested at the time of installation as well as after repairs or relocation. After all, backflow preventers are mechanical devices and, like any mechanical device, they will eventually fail. Because of this, Florida requires that every backflow prevention device must be tested at least yearly to verify its operation. Failure to do so could allow a backflow event to contaminate the public water supply and harm people or animals.