What is backflow?
Simply put, backflow means an undesirable reversal of flow in the water distribution system. Common causes for backflow are main pipeline breaks and high rates of water withdrawal, however these incidents can be avoided with the use of backflow prevention devices. The City of Lubbock works hard to prevent backflow through ordinances requiring backflow prevention devices on home irrigation systems and at commercial businesses. Irrigation systems are required to have some sort of backflow prevention installed at the system’s source (where it connects to a drinking water supply). The backflow prevention assembly ensures that any substance on your lawn such as pesticides, herbicides and fertilizers does not end up in your cup of coffee or glass of tea.
There are two types of backflow:
- Backpressure backflow, the pressure outside the water distribution system exceeds the pressure within the system.
- Backsiphonage, potentially contaminated water flows back into the drinking water system, as a result from the pressure in the drinking water system falling below atmospheric pressure of the plumbing fixtures.
For more information: Businesses please call Barry Stephens at 806-775-3604; Homeowners please call Cesar Castanon at 806-775-2589. For emergencies please call Water Dispatch at 806-775-2588.
Simple Steps to Prevent Backflow:
Guard against cross connections. A garden hose is directly connected to the drinking water in a home, and is the most common cross connection. When using a chemical sprayer that connects to a garden hose or filling a swimming pool, a Hose Bib Vacuum Breaker attached to your hose faucet is required. Hose Bib Vacuum Breakers are inexpensive, widely available and easily screw on to your hose faucet.
Make sure a backflow prevention device is installed on your home sprinkler system. Common devices are a Double Check Valve Assemblies and Pressure Vacuum Breakers. If you decide to install a lawn sprinkler system on your property, you need to make sure that the water from your sprinkler system cannot end up into your drinking water. You are required to install an approved backflow prevention device to prevent possible contamination of the drinking water supply.
Four Common Types of Backflow Prevention Devices for Irrigation Systems
Double Check Valve Assembly (DCVA)
- This is the most widely used backflow prevention device on sprinkler systems. It can be installed below grade in a standard rectangular valve box. The irrigation system can be turned off at 1 of 2 shut off valves on the assembly.
Pressure Vacuum Breaker (PVB)
- This device is approved for irrigation systems; however, it is rarely used because of its limitations. It must be installed above grade, 12 inches above the highest downstream sprinkler head and is subject to freezing in winter months. This device is also approved for chemical injection systems on sprinklers. The irrigation system can be turned off at 1 of 2 shut off valves on the assembly.
Reduced Pressure Zone Assembly (RPZA)
- This device is approved for irrigation systems; however, it is rarely used because of its limitations. It must be installed a minimum of 12 inches above grade, and is subject to freezing in winter months. This device is also approved for chemical injection systems on sprinklers and systems that might create backpressure. The irrigation system can be turned off at 1 of 2 shut off valves on the assembly.
Atmospheric Vacuum Breaker (AVB)
- This device is commonly found on older sprinkler systems, but is not approved for new installations because it is non-testable and cannot have any downstream valves. It must be replaced by a Double Check Valve Assembly when upgrading an irrigation system. There are no shut off valves to isolate the irrigation system.
Backflow Prevention FAQs
Certified Backflow Tester List
Test and Maintenance Form Instructions
Backflow Test and Maintenance Report Form 2017
Instructions for Saving a Fillable PDF