Backflow Preventer

August 14, 2009



Backflow preventers are mechanical safety devices designed to prevent water from flowing opposite its intended course.

Photo Courtesy of Watts Regulator Company
Photo Courtesy of Watts Regulator Company

Backflow preventers come in a variety of shapes and sizes and are used in many different applications. The most common application is found in residential irrigation systems. In this application, the backflow preventer is used to prevent contaminated water (water contaminated by fertilizers, animal droppings, etc.) that may gather around sprinkler heads from being siphoned into the potable water supply.

Many municipalities require that backflow prevention devices be installed just beyond the water meter. This requirement helps protect the municipal water source as a whole. The backflow preventer installed at the water meter doesn’t protect the homeowner, but rather all of his neighbors. When everyone has a backflow preventer, it is comforting to know that our chances of becoming ill due to the actions of our neighbors are greatly reduced.

Most manufacturers specify that the device be tested annually by a properly trained and licensed tester. Please see Backflow Testing in our Services section.

Note: When a backflow preventer is installed between the meter and the main water supply of the dwelling, the system becomes a “closed” system. Please see the Thermal Expansion section for more information.