Cross-Connection Control and Backflow Prevention Program

Denver Water’s Cross-Connection Control and Backflow Prevention Program protects the public water supply from pollutants and contaminants that could, under certain circumstances, be drawn into the public water supply from private properties.

All commercial, industrial, domestic, irrigation and fire line services are required to have an approved backflow prevention assembly installed. Requirements for multi- and single-family residences are assessed based on site hazards. All customers with an auxiliary water supply, such as a well or a pond, are also required to install and maintain backflow prevention assemblies.

The Colorado Department of Public Health and Environment regulates drinking water quality and standards. The Colorado Primary Drinking Water Regulations (PDF document Section 11.39) outline Denver Water’s requirements for cross-connection control and backflow prevention.

In addition to installing an assembly, the water customer must have the assembly tested upon installation and annually thereafter by a certified backflow prevention assembly tester. All testing must be reported to Denver Water’s Cross-Connection Control office.

  • Backflow

    Backflow is the unwanted flow of water or other liquids, mixtures, gasses or substances into the drinking water supply.

    There are two main ways backflow can occur:

    • Backsiphonage occurs when there is a negative pressure in the water distribution system, which draws the water from a private water system into the public water system. This can occur at any time, such as during a water main break or during a large firefighting effort.
    • Backpressure occurs when the pressure in a private water system exceeds the pressure in the public water distribution lines that can cause normal flow to reverse. A pump used to increase the water pressure within a building’s plumbing system to reach a higher floor might cause this.
  • Cross-connections

    Cross-connections are actual or potential connections between the public water supply and any other system that could accidentally introduce a contaminant back into the public water supply.

    According to the Environmental Protection Agency, cross-connections can be a serious public health hazard if they do not have adequate backflow prevention assemblies installed. There are numerous, well-documented cases in which cross-connections have been responsible for contamination of drinking water that, when consumed, caused the spread of sickness or disease.

  • Backflow prevention assemblies

    A backflow prevention assembly is a mechanical valve arrangement designed to prevent the reversal of the flow of water once it has passed through the valve.

    Like any mechanical device, a backflow prevention assembly requires maintenance and annual testing. There are different types of backflow prevention assemblies required for different uses and different degrees of hazard.

    There are no exemptions or grandfathering in of backflow prevention assembly requirements.

  • Approved backflow prevention assemblies

    Backflow prevention assemblies installed within Denver Water’s distribution system must be approved by the University of Southern California’s Foundation for Cross-Connection Control and Hydraulic Research, otherwise known as being USC-approved.

    Check with your backflow prevention assembly manufacturer or the product specification sheets to verify that the assembly is USC-approved. You must also confirm the assembly is approved in the orientation for which it is being installed (horizontal, vertical, etc.).

  • Types of backflow prevention assemblies

    Reduced Pressure Principle Assembly (RP)

    Reduced Pressure Principle AssemblyAn RP is required for most commercial, industrial and irrigation domestic water applications.

    Installation requirements:

    • Install a minimum of 12 inches off the floor and 12 inches away from a wall.
    • If the assembly is installed higher than 5 feet off the ground, a platform is required for access and maintenance.
    • Adequate drainage is required, as there is a potential for discharge from the unit.
    • Protect from freezing.

    Double Check Valve Assembly (DC)

    Double Check Valve AssemblyA DC is required for fire lines without antifreeze or chemical additives and some residential applications. They are not allowed for irrigation systems.

    Installation requirements:

    • Install a minimum of 12 inches off the floor and 12 inches away from a wall.
    • If the assembly is installed higher than 5 feet off the ground, a platform is required for access and maintenance.

    Pressure Vacuum Breaker (PVB)

    Pressure Vacuum BreakerPVBs have historically been used as protection for irrigation systems. Denver Water no longer allows the installation of new PVBs for irrigation. Existing PVBs that can be repaired will be accepted. Any new installations must use a Reduced Pressure Principle Assembly (RP).

    Installation requirements:

    • Must be installed a minimum of 12 inches above the highest point of use and 12 inches away from a wall.
    • Cannot be subjected to continuous backpressure.

    Atmospheric Vacuum Breaker (AVB)

    Atmospheric Vacuum BreakerAVBs are generally used as point-of-use devices for a specific, internal plumbing process. Denver Water does not allow AVBs for any type of containment uses. Irrigation systems must be protected with a Reduced Pressure Principle Assembly (RP).