Environmental Quality | 206 W. Church St., 2nd Floor | P.O. Box 534045 | Grand Prairie, TX 75053
Phone 972-237-8055 | Fax 972-237-8228
Backflow is the undesirable reversal of water flow potentially bringing contaminants into your drinking water system. The two types of backflow are back-pressure and back-siphonage. Back-siphonage occurs when there is reduced pressure in the drinking water supply line and is frequently caused by under-sized piping, plumbing repairs, a water main break, or activated fire hydrants. Back-pressure occurs when the drinking water system is connected to another, higher pressure system. Common causes are booster pumps and boilers.
A cross-connection is a point in the plumbing system where the drinking water is connected to a contaminated or non-potable source. Contamination of the water supply results when the non-potable source backflows through the cross-connection into the plumbing system. For example, without a backflow prevention device, antifreeze from a heating system can backflow through a cross-connection and contaminate drinking water.
The potential health hazard created by a cross-connection determines the type of device required for backflow prevention. The following are common backflow preventers, methods, and uses.
- Devices must not be installed more than five feet off the ground unless a permanent platform is provided.
- The device must be accessible to testers.
All new installations of backflow devices require a plumbing permit from the City's Building Inspection division. Only a licensed plumber/irrigator may install or replace a backflow prevention device. Environmental Services performs inspections and tests on all new backflow device installations. To schedule a test or for more information on backflow prevention devices, call 972-237-8055.