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Cross-Connection Control and Backflow Prevention

Information for public water systems and their customers on identifying potential cross connections and preventing contamination from backflow into drinking-water systems.

To protect public health, our Cross-Connection Control (CCC) and Backflow Prevention Program is committed to helping you protect your drinking water system from potential contamination. The Cross-Connection Control Subcommittee advises us in this effort.

How Cross Connection and Backflow Can Lead to Contaminated Water

It really happened in Texas:

  • While mixing a batch of pesticide, a worker pushed a garden hose into the tank until it touched the bottom.
  • Nearby, city utility workers opened a flush valve, releasing a large flow of water from a water main.
  • Where the worker was mixing the pesticide, the water pressure dropped, and the flow in the hose reversed. Water and pesticides flowed from the pesticide tank back through the hose and into the water lines of the residence.

Luckily, this is where it stopped: The worker mixing the pesticide realized the danger and alerted the utility workers, who closed the flush valve before the contamination reached the city’s distribution line. Still, good water and time were wasted:

  • To remove the pesticide from the water lines of the customer, utility workers flushed those lines.
  • In case the water main had been contaminated, the utility workers had to flush the city’s distribution line, too.
  • Until testing showed authorities that the city’s water was safe, they warned customers in the area not to drink it.

As shown by the case histories of backflow incidents   maintained by the backflow-prevention education program of the University of Florida’s TREEO Center, not all cases of cross connection and backflow end so smoothly.

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cross connection
a physical connection between drinkable water 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 from the liquid or gas contaminants)
water flowing opposite to its intended direction, either from a loss of pressure in the supply lines or an increase in pressure on the customer’s side (in either of these situations, if any affected customer’s pipes include a cross connection, contaminants could be drawn through the cross connection into that customer’s pipes—and, if the backflow continues, perhaps even into the water mains)

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Your Role as a Water Customer

By taking steps to control cross connections and prevent the possibility of backflow at your home, you will help to protect the public water supply and ensure that your family continues to enjoy safe drinking water. Garden hoses and irrigation systems are common concerns, but there are other common residential sources of cross connections, too.

Garden Hoses and Backflow

The garden hose is the most common cross connection. Each of these common uses of a garden hose sets up a cross connection:

  • forcing it into a clogged gutter, downspout, or sewer pipe to flush out the clog
  • connecting it directly to a hose-end sprayer to apply pesticide or fertilizer to your yard
  • connecting it to a soap-and-brush attachment to wash your car, boat, or siding
  • letting the end of the hose lie in a puddle or pool of water on the ground

No doubt you can think of other examples. In each of these cases, if backflow happens, your household’s water lines could be contaminated. Depending on how long the backflow event lasts, the contamination could spread to the public drinking water system. Fortunately, there are two inexpensive ways to solve this problem:

  • Make sure that the end of your garden hose is never submerged in or connected to a nonpotable substance. This solution is free, but not highly reliable. Can you always be this careful?
  • Install a hose bibb vacuum breaker on each of your outside faucets. These inexpensive devices are designed to allow water to flow in only one direction. You can find them at most home supply stores and through plumbing suppliers. Before you use a hose-end sprayer, you should first install a hose bibb vacuum breaker at the faucet.

Irrigation Systems and Backflow

As a homeowner, you may install and maintain your own irrigation system, but it’s still important to have a suitable backflow prevention assembly (BPA) in place and to be sure that it works properly. Here are a few ways you can do just that:

  • Hire a licensed irrigator. You can find one from our online licensing database.
  • If you install your own system, have a licensed BPA tester confirm that the BPA is installed and operating properly. Licensed BPA testers are also listed in our online licensing database.
  • TCEQ requires you to have a licensed BPA tester check the BPA when it is installed on your irrigation system. Your water provider may have adopted additional codes or regulations which require an annual test of the BPA on your irrigation system.

For more information see TCEQ's regulations for irrigation systems, or contact TCEQ's Landscape Irrigation Program at 512-239-LAWN.

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Your Water System’s Role

Your water system’s role begins with good system maintenance and sound operations. By replacing pipes before they break, taking steps to ensure that system pressures do not fall during periods of high demand, and asking for the cooperation of customers when there is a risk that system pressures could fall below safe levels, your public water system operator reduces the risk of backflow.

Many public water systems also operate rigorous cross-connection control (CCC) programs of their own. They identify locations where the risk of cross connection is high and ensure that the proper measures are taken to minimize that risk. For example, these and other businesses would be required to install high-grade backflow prevention assemblies and have them tested by a certified tester annually:

  • mortuaries
  • minor surgery centers
  • hospitals
  • chemical plants

Another aspect of an effective CCC program is the customer service inspection (CSI). Your public water system must require a CSI to be performed under the following circumstances:

  • All new construction.
  • Existing customers that have had substantial plumbing modifications.
  • Existing customers whenever there is a reason to suspect that a hazard or a source of contamination may be present.

Water providers notify their customers that a CSI is required.  Some public water systems have licensed staff who perform the CSIs and then bill the customer for the inspection.  Other public water systems require the customer to hire a licensed person to conduct the CSI.  The following individuals are authorized to perform CSIs:

  • A TCEQ-licensed Customer Service Inspector.
  • A Texas State Board of Plumbing Examiners (TSBPE) licensed Plumbing Inspector.
  • A TSBPE-licensed plumber with a Water Supply Protection Specialist endorsement. 

Our Occupational Licensing Section licenses Customer Service Inspectors and maintains a database of licensed Customer Service Inspectors.

To learn more, read Introduction to Cross-Connection Control   or the technical guidance.

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The TCEQ’s Role in Cross-Connection Control and Backflow Prevention

We require water providers to meet standards to obtain, treat, and deliver water. A public water system’s Cross-Connection Control Program is inspected during routine investigations made by our regional staff. Technical assistance in the area of cross-connection control is offered to public water systems by staff from our central office.

We also coordinate meetings of the Cross-Connection Control (CCC) Subcommittee, a group of participants that meet to discuss issues related to cross-connection control and backflow prevention. A voluntary group that is open to anyone who would like to join, the CCC Subcommittee provides us with expanded knowledge and resources to address cross-connection control and backflow prevention throughout Texas.

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Technical Guidance

Official Cross-Connection Control Program forms:

Listed below are links to the official TCEQ Cross-Connection Control Program forms. Please note that these forms are periodically updated so, for the most up to date version of the forms, please use the links on this page. TCEQ regulations require that any alternate forms which vary from the official forms receive TCEQ approval prior to being placed in use. Be aware these forms must be submitted to the responsible water system for recordkeeping purposes.

The addition of a PWS logo, with no further alterations, to the TCEQ official forms, TCEQ 20699 and TCEQ 20700, does not require submittal or approval of an alternate form.

  • Sample Service Agreement (290.47(b))
  • Customer Service Inspection Certificate (Microsoft Word Document TCEQ Form 20699
    • A Customer Service Inspection Certificate (CSI) is used to document the findings of a Customer Service Inspection.
  • Backflow Prevention Assembly Test and Maintenance Report  (Microsoft Word Document TCEQ Form 20700 Word)  / ( TCEQ Form 20700 PDF)
    • This report is used to document the results of testing a backflow prevention assembly for proper functioning.

A partial listing of common cross-connection hazards:

Individual copies of these publications are free:

      • Customer Service Inspections: A Guide for Public Water Systems (TCEQ publication RG-206)
      • Backflow Protection on Fire Prevention Systems (TCEQ publication RG-345)
      • A Public Water System Guide to Preparing a Backflow-Incident Emergency-Response Plan (TCEQ publication RG-477)
      • A Public Water System Guide to Responding to a Backflow Incident (TCEQ publication RG-476)
      • Establishing and Managing an Effective Cross-Connection Control Program (TCEQ publication RG-478)
      • EPA’s Cross-Connection Control Manual  

These manuals are available for purchase from their publishers:

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Staff Contact

For more information, call our main Water Supply Division line, 512-239-4691, and ask for the Cross-Connection Control and Backflow Prevention Program coordinator. You may also e-mail your question or comment to Please include “Cross-Connection/Backflow Prevention” in the subject line of your e-mail.

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