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.
All new firelines require a Double Check Detector Assembly (DCDA).
Fireline assemblies can only be tested by a state certified, city registered tester who is a full-time employee of a licensed fireline contractor.