Cross Connection / Backflow Prevention

Program Purpose

The purpose of a Cross Connection Control Program is to identify potential cross connections on the public water system and require that the proper backflow prevention device is installed at the potential source.


Cross Connection – a physical connection, directly or indirectly (actual or potential), between a drinkable water system and a liquid or gas that could make the water unsafe to drink. Wherever there is a cross connection, there is a potential threat to public health.

Backflow Prevention Device / Assembly

Backflow Prevention Device / Assembly is an approved, testable device that prevents backflow, backpressure and/or backsiphonage from occurring in the water supply line. Devices must be approved by the University of Southern California Foundation for Cross Connection Control and Hydraulic Research. To see a list of approved devices please go to www. The type of device required is determined by the degree of hazard and type of application.

Backflow Prevention Devices must be installed by a registered plumber or backflow installer and then tested by certified backflow tester who is registered with the Cross Connection Department. The original test report must be turned into the Cross Connection Department within one business day.

All residential irrigations systems, except those that use chemicals and/or fertilizer injection systems, are required to install a minimum of a double check valve and they are to be tested upon installation and every other year thereafter.

Irrigation Fittings

Backflow Assembly in Box

Backflow Prevention Assembly Test & Maintenance Report Form

Irrigation systems with chemical/fertilizer injection systems must install Reduced Pressure Zone backflow devices and are required to be tested upon installation and once a year thereafter.

All commercial backflow devices will be determined based on the type of application and degree of hazard. These devices are required to be tested every year.

Related Links

Frequently Asked Questions

Why do I need a backflow prevention device on my lawn irrigation system?

All lawn irrigation systems in the City of Duncanville are required to have an approved backflow prevention device installed on them. This is to prevent the water that is in your irrigation system from backflowing or back-siphoning into your drinking water and the city’s water supply. The water in your irrigation system is exposed to bacteria and organisms in the ground, fertilizers that are applied to your lawn, and even animal feces.

How often does my backflow prevention device have to be tested?

Residential lawn irrigation backflow prevention devices (such as double-check valves and pressure-vacuum breakers) must be tested biannually, or every two years. Commercial backflow prevention devices must be tested annually, or once a year. The test must be preformed by a certified backflow tester who is registered with this office. Please contact this office for a list of testers at (972) 780-4946 or (972) 780-4900.

What do I need to do to register as a backflow tester with the City of Duncanville?

Certified backflow testers will need to go the Service Center located at 330 Shady Trail, Duncanville, TX 75137. You will need to come in person to fill out a couple forms. Testers need to bring copies of their: Backflow Prevention Assembly Tester License, Gauge Calibration, Confined Space Training Certificate, Commercial Certificate of Liability Insurance, and Fire Line Licenses if applicable.