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Backflow Prevention

What is Backflow?

Backflow protection prevents undesirable water, sewage, or chemical solutions entering your drinking (potable) water system.

Backflow and back siphonage are two causes of water contamination.

Backflow is the reversal of normal flow due to backsiphonage or backpressure.

Backsiphonage occurs when a vacuum is induced (a stoppage in the water supply), like drinking from a glass through a straw.

Back siphonage can be caused by:

• Watermain breaks or repairs at lower elevation than the service point
• High water flow from system demands, such as a break in the line, firefighting use
• Undersized piping

Backpressure on the flow happens when downstream pressure is greater than the supply pressure.

Back pressure can occur when the following are connected to the drinking water system

• A non-potable system with pumping system is inter-connected
• Heat exchange
• Steam or hot water boilers.

Contamination of the water supply is an actual health hazard; a consumer is being subjected to potentially lethal water borne disease or illness.

Common uses of water that could pose a threat to drinking water include:

• Hose connections to chemical solution
• Lawn sprinkler systems
• Chemically treated heating systems
• Water softeners
• Hose connections to water outlet, laundry tub
• Swimming pools
• Solar heating systems
• Private non-potable water supplies
• Non-approved ballcock assemblies in toilets
• Water operated sump drain devices

What is the Law?

The State of Michigan Department of Environmental Quality, Michigan's Safe Drinking Water Act, P.A. 399, 1976 (As Amended), Michigan Plumbing Code 2000, and local townships' Cross Connection Control Ordinance require backflow prevention device installation and regular testing.

Questions concerning backflow prevention may be directed to: Grand Traverse County Department of Public Works at 231 995-6039; the Michigan Department of Public Health-Division of Water Supply at 517 335-9216; or the Michigan Department of Labor - Plumbing Division at 517 322-1804Permits A plumbing permit may be required for installation of the backflow device, information can be obtained from the Grand Traverse County Construction Code Office 231 995-6049.

All Irrigation Systems require an air gap or backflow protection device.

Connections subject to back pressure shall be made by means of an air gap with a surge tank and pump. If this is not feasible the use of a reduced pressure zone backflow preventer is required with a design submitted to the Plumbing Inspector for approval before installation

Inspections are completed by the Cross Connection Control Water and Sewer Technician from the Department of Public Works on a scheduled basis. The Plumbing Inspector verifies compliance to the Plumbing Code.

Regulations, Backflow Prevention Devices, Testing

All testable devices are to be tested upon installation and tested annually thereafter. The County may require more frequent testing based upon degree of hazard, corrosive atmosphere or concerns with water quality.

Testable devices are:

Double Check Valve Assembly Reduced Pressure Backflow Preventer Assembly

Reduced Pressure Detector Assembly Spill Resistant Vacuum Breaker

Double Detector Check Valve Assembly Pressure Vacuum Breaker

Testers certified by the State of Michigan can test or install backflow prevention devices. (An area listing of Certified Testers is available from the Department of Public Works Shop office, 231 922-4896.)

Testing cost varies by device type and certified tester performing the test. Typically the testing takes 10-30 minutes. The water supply to the backflow preventer is off during testing