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Definitions and Terms
Backflow in the water distribution system happens as a result of a reversal of the normal flow of water in the system. The two types of backflow are backsiphonage or backpressure. Backsiphonage is the reversal of flow of liquid caused by a partial vacuum in the potable water distribution system. This condition occurs when the supply pressure drops below atmospheric pressure. Backpressure is a condition in which the pressure in a non-potable system is greater than the pressure in a potable water system. Superior pressure will cause non-potable liquids to flow into the potable water distribution system through cross-connections.
Backflow into the water system can make the water unusable or unsafe to drink. The City of Lynchburg’s goal is to supply safe drinking water to every customer. The number one priority of the Utilities Department is to supply safe public drinking water.
In order to prevent backflow from entering the water distribution system, the City of Lynchburg requires that a backflow preventer be installed at each service connection where hazards are found. A backflow preventer is a mechanical assembly that prevents the backflow of pollutants or contaminants into the potable water distribution system. There are different requirements based upon the type of service connection and hazards identified at the location. Specific guidelines for backflow preventers at each type of connection, as well as hazard, are outlined in the program to ensure that each connection is properly protected.
Cross-connections may be found but not necessarily limited to the following types of facilities. Any cross-connections that are located must be eliminated by installing the proper backflow prevention assembly.
- Hospitals, mortuaries, clinics, veterinary establishments, nursing homes, and medical buildings;
- Laboratories;
- Piers, docks and waterfront facilities;
- Sewage treatment plants, sewage pumping stations, or storm water pumping stations;
- Food and beverage processing plants;
- Chemical plants, dyeing plants and pharmaceutical plants;
- Metal plating industries;
- Petroleum or natural gas processing or storage plants;
- Radioactive materials processing plants or nuclear reactors;
- Car washes and laundries;
- Lawn sprinkler systems, and irrigation systems;
- Fire service systems;
- Slaughter houses and poultry processing plants;
- Farms where the water is used for other than household purposes;
- Commercial greenhouses and nurseries;
- Health clubs with swimming pools, therapeutic baths, hot tubs, or saunas;
- Paper and paper products plants and printing plants;
- Pesticide or exterminating companies and their vehicles with storage or mixing tanks;
- Schools or colleges with laboratory facilities;
- High-rise buildings (four or more stories);
- Multiuse commercial, office, or warehouse facilities; and
- Others specified by the purveyor or the division when reasonable cause can be shown for a potential backflow or cross connection hazard.
The Water Purveyor’s responsibilities for cross-connection control lies with the containment of the building and service connection. The Water Purveyor is not responsible for any internal cross-connections within the plumbing system of the facility. Recommendations can be made but the responsibility to correct any cross-connections within the facility lies with the Building Code Official, building owner and any contractors performing work on the plumbing system.
