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Backflow / Cross-Connection
Backflow Prevention Assemblies
The Town of Boone is required by law to have a cross-connection control program to assure the public water system is adequately protected from the potential dangers of backflow and cross-connections.
This can only be accomplished by the installation of an approved mechanical device and annual testing. This will prevent contaminated water from re-entering the distribution system. These devices are called “Backflow Prevention Assemblies” and are required to be installed on all commercial water lines, lawn irrigation lines, and fire sprinkler lines connected to the Town of Boone’s distribution system.
All “Backflow Prevention Assemblies” must be installed by a licensed plumber and tested by a Town-approved certified tester annually to maintain compliance with the program requirements.
Water distribution systems are designed with the intention of the water flowing in a certain direction, from the distribution system to the consumer. However, hydraulic conditions within the can change from normal conditions, causing the water to floe in the opposite direction. This is called “Backflow”. Backflow can occur in two ways:
Sometimes the pressure in the distribution system will drop because of water main breaks or the opening of fire hydrants and create a siphon affect and cause the water and or contaminants from the consumer side to be siphoned back into the distribution system. This is called Back Siphonage.
Some customers have objectionable materials on their premises under pressure by the use of pumps, injection units, boilers, etc. The large amount of pressure will cause the water and or contaminants from the consumer’s side to push its way back into the distribution system therefore, contaminating the distribution system. This is called Back Pressure.
A cross connection is a permanent or temporary piping arrangement which can allow your drinking water to be contaminated if a backflow condition occurs. There are two types of cross connections, direct and indirect. A “direct” cross connection is subject to both back pressure and back siphonage, while an “indirect” cross connection is subject only to back siphonage. The following list is a few examples of cross connections:
- Garden hoses attached to water supply that are placed in buckets of standing water, chemicals, or in swimming pools, pets watering bowls, and garden sprayers (Indirect Cross Connection)
- Water faucet that is not high enough to avoid contact with standing water or chemicals (Indirect Cross Connection)
- The overflow tube in the toilet tank installed at an improper height, which could allow the fill valve to become submerged(Indirect Cross Connection)
- Landscape watering systems that inter-connect city water with an irrigation water supply(Direct Cross Connection)
- Fire pressure pump tied into sprinkler system and connected to the city water supply (Direct Cross Connection)
More information can be found in the Backflow / Cross Connection Information (PDF).