The words "cross connection" may not mean much to most, but to the employees of the City Water Department, and especially Ron Ison and Donnie Ford, Water Quality Control Specialists, the words mean trouble. What is cross connection? Simply put, cross connection occurs when contaminated water, potentially hazardous gas or liquid, gains entrance to and pollutes a safe water supply. Through the careful monitoring of the City water supply system and the installation of backflow prevention assemblies, the risk of cross connection can dramatically be reduced.

A backflow prevention assembly prevents potentially dangerous substances or contaminated water from entering the public water supply. This assembly consists of a valve that allows water to enter a building but prevents the water from returning to the supply line. Cross connection contamination usually occurs when there is a loss of pressure in the City system. The loss of pressure can create a siphonage situation that will actually pull the water from a building back into the system.

In 1996 the City implemented a BMA approved Cross Connection Control ordinance. The State Division of Water Quality requires that all public water systems maintain an active program to identify and control cross connections. This ordinance is the basis for the City's program. Everyone that installs or repairs these assemblies is required to be certified by the State of Tennessee.

There are 10 City employees certified for cross connection and backflow prevention installation and repair. To date the City has had 1200 backflow prevention assemblies installed and are maintained by City staff.

Click on the file below to link to the City's policy for Backflow Prevention Requirements.

Only units currently approved by the TN Division of Water Supply are to be used for the protection of Public Water Systems against backflow hazards. For the information on any units that may have been approved since the printing of this list call the Division of Water Supply at (615) 532-0164 or the Fleming Training Center at (615)898-8090.

Note: Double check-detector check and double check valve assemblies have only been approved by the Division of Water Supply for certain (moderate to low hazard) fire service lines. Reduced pressure backflow prevention devices are required for domestic and/or process service lines where maximum backflow protection is needed.

Unless otherwise specified by the manufacturer all assemblies are to be installed on cold potatle water applications - below 110 F. Also all Double Check Valve Assemblies, Reduced Pressure Principle Assemblies, Double Check Detector Assemblies, and Reduced Pressure Principle Detector Assemblies are Approved for HORIZONTAL ORIENTATION ONLY, unless specifically noted. Use of spare parts other than those of the original manufacturer invalidates the Approval. The following are lists of Approved assemblies by manufacturer.