The Public Water System Cross-Connection Control Approach

Containment Protection also known as service line protection or premises isolation is an approach that is utilized by most public water system. Several options are open to a public water system when considering cross-connection protection to commercial, industrial, and residential customers. The public water system cross-connection program may consist of the “containment” theory. This approach isolates the customer from the water main. It virtually insulates the customer from potentially contaminating or polluting the public water distribution system. The containment approach alone does not protect the consumer of water within building, therefore is not considered a complete cross-connection control program.

The containment approach alone should not be utilized by the public water system to control cross-connections but should be augmented by fixture outlet approach to cross-connection control. “Fixture outlet protection” or “in-plant protection” provides protection to all water consumers including the public water distribution system. As illustrated all fixture outlets cross-connection are control by air gaps or backflow prevention devices installed on each fixture. Backflow prevention devices installed on the piping feed lines to process tanks and boilers protect the internal piping cross-connections. Note the location of a dedicated potable water line. It is downstream of the meter and upstream of the backflow prevention device.

When a backflow prevention device is installed on the service line, the term “containment” should be avoided since it could cause confusion. Containment would imply that the backflow prevention device is installed to control cross-connections located within the facility domestic water system. Controlling cross-connection where they occur protects the consumers of water within the building and the public water system.

The term “service line protection” should be used to describe the installation of a backflow prevention device on the service line, since the public water system is simply isolating two potable water systems, the public water system and the domestic or internal water system. Service line protection means the installation of a backflow prevention device for hydraulic purposes. Plumbing codes requires the delivery of potable water to all plumbing fixtures that provide water for drinking, bathing, or culinary purposes. Installing a backflow prevention device on the service line for cross-connection control would be in conflict of the plumbing codes since the definition of a cross-connection is the connection between the potable water system and a non-potable water. The term service line protection should be utilized instead of containment protection for the installation of backflow prevention device on service lines. A service line protection device would mean a backflow prevention device used for hydraulic purposes to prevent the flow of potable water from one potable water system into another potable water system.

The term containment backflow installation should be reserved for a backflow prevention device installed to isolate a non-potable process water line downstream of the meter. In this installation, all potable water lines are connected downstream of the meter and upstream of the containment backflow prevention device. Controlling cross-connection on the potable water line would be subject to the plumbing codes utilizing fixture outlet protection devices. There shall be no potable water use downstream of the containment backflow prevention device. This tactic to controlling cross-connection can be considered the dedicated line approach. All piping shall be color coded and properly labeled pursuant to the plumbing codes.

Containment terminology should be reserved for backflow prevention devices installed on fire protection systems, since the water used in this piping system for firefighting purposes and is not potable.

Many public water systems are now requiring containment at the water meter as a condition for the water user to receive or continue to receive the public water supply. The approach only protects the public water system distribution system and does not protect the potable water within the facility. This approach to controlling cross-connections insulates the customer from potentially contaminating or polluting the public water system. Since the individuals within the building are still at risk, the public water system could be presented with a liability issue. To protect the public health of all the consumers of water, the public water system must include a program to protect the consumer of water within the building from the impacts of unprotected cross-connections.