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Backflow Prevention


Preventing backflow is an important part of maintaining a healthy water supply. The City of Lubbock’s water distribution system is designed to carry water from the water treatment plant to the consumer. Cross connections, or connections between potable water in the distribution system to any non-potable water, exist. These connections make the water distribution system susceptible to backflow, which is the reversal of water flow from its intended direction. In other words, non-potable water could be introduced into the distribution system.

There are two types of backflow:
  • Backpressure backflow, which occurs when the pressure outside the water distribution system exceeds the pressure within the system.
  • Backsiphonage, which occurs when a partial vacuum is created in the system sucking non-potable water back into it.


Three Common Types of Backflow Prevention Devices for Irrigation Systems


Pressure Vacuum Breaker
 
This device is approved for irrigation systems, however it is rarely used because of above ground installation and is subject to freezing during winter months. This device is also approved for chemical injection systems on sprinklers. Irrigation system can be turned off at 1 of 2 shut off handles.



Atmospheric Vacuum Breaker

This device is commonly found on older sprinkler systems, but is not approved for new installations because it is non-testable. It must be replaced by a Double Check Valve when upgrading irrigation system. No shut off handles to isolate irrigation system.


Double Check Valve

This is the most widely used backflow prevention device on sprinkler systems. It is installed below grade in a standard valve box. Irrigation system can be turned off at 1 of 2 shut off handles.

Simple Steps to Prevent Backflow:
  • Guard against cross connections. A garden hose is a direct connection to the drinking water in the home. Don’t attach chemical sprayers or leave a garden hose submerged in a swimming pool. (Hose Bibb Vacuum Breakers may also be installed on garden hoses)
  • Make sure backflow prevention device is installed on your home sprinkler system. Common devices are Double Check Valve Assemblies and Pressure Vacuum Breakers.