Backflow Prevention for Commercial Facilities


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.

Cross Connection

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.

Installation Requirements

  • 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.

Permit Requirements

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.


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Fireline Requirements

  • 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.

Backflow Prevention Ordinance

Backflow Documents


  • This section is under construction.