Irrigation Equipment - Backflow Prevention Devices

Backflow Prevention Devices: The State of Texas requires every lawn sprinkler system installed in the State to be protected by a certified backflow prevention device. These devices are required to protect the quality and safety of the drinking water supply.

What is Backflow and Why Should It Be Prevented?

Backflow is defined as the undesirable reversal of flow in a potable water distribution system as a result of a pressure differential or siphon condition that exists between two piping systems. Backflow is a problem where there is a desire to keep fluids from one piping system from re-entering another piping system as in the case of a cross-connection.

A cross connection is a connection (such as a lawn irrigation system) or potential connection (such as a garden hose) between any part of a potable water system and any other environment containing other substances (such as a lawn or a container of herbicide) in a manner that under any circumstances, would allow such substances to enter the potable water system. (other examples of common cross-connections include water supplies to heating boilers and hoses feeding utility sinks)

In other words, water that goes out a faucet, sprinkler head, or emitter should never be allowed to be drawn back into the potable water system by siphon, pressure loss, or any other means.

The backflow prevention device is used to keep water that passes through it, and into the irrigation system, from coming back into the water supply. Since water in an irrigation system can be contaminated by chemicals, animal droppings, and other yard debris, it is considered non-potable. Very strict standards have been set by the TNRCC (the equivalent of the Environmental Protection Agency for the State of Texas) and proper backflow prevention is required on all irrigation systems.

What Type of Backflow Protection is Required?

There are various levels of protection required for differing situations. In most parts of Texas, a lawn irrigation system is considered a moderate cross connection hazard to the water supply. Adding chemicals, such as fertilizers or herbicides, within the sprinkler lines is considered a high hazard cross connection. Septic systems are also considered a high hazard cross connecton.

Low hazard, moderate hazard and high hazard situations each call for a different device. The backflow prevention device chosen for a system must take into consideration the highest threat possible to the potable water supply that the system will encounter. Your local water authority can provide information on the backflow device required in your area.

What About Yearly Re-certification?

Many water purveyors require yearly re-certification of the proper operation of the backflow device. See your irrigation contractor if you are notified that you need to have your existing device tested and certified.

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