Protecting Public Health and Safety


Cross-Connection Control and Backflow Prevention Program

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Cross-Connection Control and Prevention of Backflow Program

EID’s Cross-Connection Control and Prevention of Backflow Program was created in accordance with federal and state regulations to protect our public drinking water supply from contamination through sources existing downstream of EID’s drinking water meter.

Existing onsite plumbing arrangements or certain water related activities can contribute to creating an actual or potentially hazardous situation for EID’s public water system and in most cases unknowingly to the user. Due to the commonality of complex onsite plumbing systems and lack of knowledge of cross-connection hazards associated with typical water use, EID has chosen to focus backflow protection at EID’s water meter to completely isolate customer’s private system from our public water supply. Once an onsite hazard is identified EID requires the customer to install an EID approved backflow prevention assembly at EID’s water meter.

EID Backflow Prevention Testing and Maintenance Service

A Backflow Prevention Assembly, or BPA, is a check valve that is designed to allow water flow in one direction. Once a BPA has been installed and approved, EID staff conducts all state-required initial testing, annual testing, and retesting of the backflow prevention assemblies. EID also maintains and replaces all readily serviceable internal components to ensure each BPA meets annual testing requirements. Because EID provides these services, customers do not have to hire their own certified tester to test and maintain their own BPA. These services are provided through a fee based on the size of the BPA and is included on the bi-monthly water service bill.

Backflow and Cross-Connection 101

A cross-connection is a point in a plumbing system where the drinking water supply is or can be readily connected to a non-drinking water source or other contaminant.
Backflow is the undesireable reversal of water flow and can occur under two conditions: Backpressure or Back-siphonage. Backpressure occurs when water pressure from a private system overcomes the pressure of the distribution and reverses direction of flow. Back-siphonage is created when there is a sudden drop in water pressure in the public water distribution system due to line breaks, fire fighting or other high demand which can siphon contaminants into the public water system. When a cross-connection exists all that is needed to allow contaminants to enter the public water system is backflow

Please watch this informative video from the American Backflow Prevention Association explaining cross-connection control and backflow: 


Common Issues Related to BPAs


Most customers are familiar with the above ground Reduced Pressure Principle BPA which are usually located near commercial buildings. This type of BPA is designed to maintain a reduced pressure zone between two internal check valves for an added level of protection. This reduced zone also includes a vent to allow water to exit the system in the event backflow occurs. This component is sensitive to distribution mainline pressure fluctuation and can open from time to time allowing water to leak from the bottom of the device.

Freezing Temperatures

Backflow prevention assemblies exposed to freezing temperatures should be protected from freeze damage. There are many commercially available insulating products specifically designed for protecting backflow preventions assemblies. Whichever option you choose it must allow reasonable access for annual testing and maintenance by EID staff.

Theft and Vandalism

Certain types of BPAs are required to be installed above ground making them vulnerable to theft or vandalism. Due to the scrap value of bronze, BPAs have increasingly become a target for theft. We recommend the owner take steps to help prevent loss or damage of your BPA. The use of a commercially available lockable security enclosure is one way minimize theft. The use of any enclosure must meet EID’s requirements for accessibility for testing and maintenance and provide adequate drainage. Another option is to spray paint the BPA. This will greatly decrease the recycled value of bronze and be less attractive to thieves. Coatings like tar can prevent the BPA from being properly tested and/or maintained and should not be used.

Recycled Water Dual-Plumbed Use Areas

Most properties located within EID’s recycled water service area receive recycled water service for front and backyard irrigation purposes. These properties are considered dual-plumbed because they are served by two separate water systems, a drinking water service and a recycled water service. Each property using recycled water is required to have a backflow prevention assembly installed at the drinking water meter to prevent recycled water from entering the public drinking water system through backflow.


EID Board Policy 5020 -  Cross-Connection Control and Backflow Prevention

EID Administrative Regulation 5021 - Cross-Connection Control and Backflow Prevention

Cross-Connection Control and Backflow Prevention Program

Cross-Connection Control and Prevention of Backflow Program Brochure

Backflow Prevention Assembly Testing Program Brochure

List of EID Approved Backflow Prevention Assemblies

Backflow Installation Instructions    

Useful Links

American Backflow Prevention Association

State Regulations Related to Cross-Connection Control and Backflow Prevention

EID Temporary Water Use Program

EID Design and Construction Standards

  • Installation Specification ¾ inch – 2 inch (EID Standard Drawing No.W22)
  • Installation Specification 3 inch – 10 inch (EID Standard Drawing No.W22A) 
  • Installation Specification 4 inch – 10 inch Fire Service (EID Standard Drawing No.W24)
  • Installation Specification ¾ inch Double Check for Recycled Water Lot (EID Standard Drawing No.W35)
  • Installation Specification for Temporary Jumper Pipe ((EID Standard Drawing No.W26)

Program Contact
Marty Johnson
(530) 295-6868

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