Protecting Your Water: Backflow Prevention Program

Customer Self-Help

When a property requires backflow protection as mandated by California Administrative Code, Title 17, the customer will be responsible for: (1) having an approved backflow prevention assembly installed on their property and (2) ensuring this assembly undergoes routine testing on an annual basis by a certified tester. As a courtesy each year, LACWD will mail both a written notice as well as a backflow test form to each affected customer when it is time for the annual test of their backflow prevention assembly. If the test form is lost, please request a new test form by emailing or alternatively, a blank test form may be downloaded using the following hyperlink: Backflow Prevention Assembly Field Test and Maintenance Report Form.

The customer is also responsible for contracting a certified tester, providing them with the test form, and ensuring that the completed test form is emailed to before the specified due date. A list of certified testers can be found on the County of Los Angeles Public Health’s webpage:

It is recommended that the customer keeps a copy of the completed backflow test form for their own records.

A water shut-off notice will be issued to customers who fail to arrange having their backflow prevention assembly tested by a certified tester before the specified due date. If the customer is non-responsive within the allotted time, LACWD may terminate water service to the property until the assembly is tested and the completed form is submitted.

Cross-Connection Control & Backflow Prevention Program Background

A cross-connection is any connection between a safe drinking water system and any other untested water source, system, or equipment that may contain unsafe substances. LACWD’s public water systems are designed to keep water flowing in one direction—from LACWD’s water main to the customers’ connections. When an undesirable condition known as backflow occurs, water can flow in the opposite direction and may bring contaminants or pollutants into the public drinking water supply through a cross-connection.

Cross-Connection Hazard: backpressure
Cross-Connection Hazard Backsiphonage

Backflow is caused by a backsiphonage or a backpressure condition in the public water system. Backsiphonage may occur when the pressure in the public water system drops below atmospheric pressure and creates a vacuum that may pull unsafe substances into the public water supply. Backpressure may occur when the pressure from a private water system becomes greater than the pressure in the public water system. This difference in pressure may allow unsafe substances from the private water system to enter the public water system. Approved backflow prevention assemblies are designed to prevent backflow of contaminants or pollutants from entering the public water systems.

In order to protect our public water systems from potential contamination, LACWD has implemented a Cross-Connection Control and Backflow Prevention Program (Program) in accordance with the California Administrative Code, Title 17. The program consists the following elements:

  • Maintain inventory of all the backflow prevention assemblies for LACWD’s water systems
  • Ensure annual testing of all backflow prevention assemblies
  • Complete plan reviews for new connections to LACWD’s water systems
  • Train employees on cross-connection control and backflow prevention

For more information, please email at


  • Backflow Prevention Assembly Field Test and Maintenance Report Form
  • Certified Backflow Prevention Assembly Testers
    LACWD accepts test, repair, and installation of backflow prevention assemblies performed by a backflow tester certified by the County of Los Angeles Department of Public Health. A list of certified testers can be found on the County of Los Angeles Public Health’s webpage:
  • Approved Backflow Prevention Assemblies
    LACWD accepts backflow prevention assemblies approved by the USC Foundation for Cross-Connection Control and Hydraulic Research. Backflow prevention assemblies for domestic lines must also meet the “lead free” requirements per Health and Safety Code (HSC) section 116875. List of approved backflow prevention assemblies:
  • County of Los Angeles Department of Public Health
    LACWD does not monitor on-site backflow prevention assemblies that protect the internal plumbing system within the property. LACWD does not administer backflow tester certification. For annual testing of on-site backflow prevention assemblies or backflow tester certification, please contact the County of Los Angeles Department of Public Health’s Cross Connection and Water Pollution Control Program at:
    Phone: (626) 430-5290

Tell Us How We're Doing

Did you find what you were looking for? Take a short survey to help us improve your experience.
Skip to content