Backflow Prevention

Century Utilities has implemented a Cross-Connection Control Program to protect the public water systems from contamination or pollution via backflow due to backpressure or backsiphonage.

Responsibility

When the water meter is replaced or directed to be replaced by the Utility Operator/Owner, or if the Utility Operator/Owner determines that an approved backflow prevention device or assembly is required for the safety of the water system, the resident is responsible at their own expense to install an approved backflow prevention device. The resident will receive this notification in writing and will be given 90 days to have such device(s) properly installed. Once the approved backflow prevention device has been installed, the Utility Operator/Owner will come to the residence and verify that the installation satisfies the requirements of the Utility’s Cross-Connection Control Plan. Failure, refusal or inability on the part of the customer to install said devices or assemblies shall constitute grounds for discontinuing water service until such devices or assemblies have been properly installed.

Water System

The water system shall be considered as made up of two parts: the Utility System and the Customer System.

• Utility System shall consist of the source facilities and the distribution system, and shall include all those facilities of the water system under the complete control of the facility, up to the point where the customer’s system begins, which is the resident’s lot line.
• Customer System shall include those parts of the facilities beyond the termination of the of the utility distribution system that are utilized in conveying utility-delivered domestic water to points of use (resident’s lot line).

Irrigation Backflow Control

To prevent the backflow of water from an irrigation system into the potable water system backflow prevention devices are used. The three types of acceptable backflow prevention devices are as follows:

• Atmospheric Vacuum Breaker (AVB)
• Pressure Vacuum Breaker Assembly (PVB)
• Reduced Pressure Principal Backflow Prevention Assembly (RP) – not covered in this guide

The Atmospheric Vacuum Breaker (AVB)

Description: The Atmospheric Vacuum Breaker consists of a float check, a check seat and an air inlet port. During normal operation water pressure forces the float check up against the float seat, allowing water to flow through the device. Fig. 1

When the flow of water to the device is shut down the float drops, thus opening the air inlet valve. The air inlets will relieve any vacuum conditions that are created. If the float seals against the check seat no water can backflow through the device. Fig. 2

Installation:

1. An AVB must be installed at least 6 inches above the highest sprinkler head.
2. There can be no valves installed downstream (after) an AVB. Therefore an AVB needs to be installed on each irrigation zone, after the solenoid valve.

Testing: Atmospheric Vacuum Breakers do not have to be tested annually.

Examples of Atmospheric Vacuum breakers:

Three Atmospheric Vacuum Breakers with Solenoid valves. Atmospheric Vacuum Breaker Atmospheric Vacuum Breaker

The Pressure Vacuum Breaker Assembly (PVB)

Description: A Pressure Vacuum Breaker Assembly consists of an independently operating internally loaded check valve and an independently operating loaded air inlet valve with shutoff valves attached to each end of the assembly. During normal operation water pressure forces the check valve open and the air inlet valve closed. This allows water to pass through the assembly. Fig. 4

When the flow of water to the assembly stops the check valve closes and the air inlet valve opens. This prevents any water from back flowing through the assembly. Fig. 5

Installation:

1. A PVB must be installed at least 12 inches above the highest sprinkler head.
2. Can have valves downstream (after) of PVB

Testing: Pressure Vacuum Breaker Assemblies MUST be tested annually.

Examples of Pressure Vacuum Breaker Assemblies:
Pressure Vacuum Breaker

Pressure Vacuum Breaker Pressure Vacuum Breaker