Frequently Asked Questions - Backflow

Q	What is backflow?
A	Backflow is the reverse of the normal flow of water. There are two types of backflow: back-siphonage and backpressure.
Q	What is back-siphonage?
A	Back-siphonage is a reverse flow of liquid caused by a partial vacuum in the potable water distribution system. This is a condition that occurs when the supply pressure drops below atmospheric pressure.
Q	What is backpressure?
A	Backpressure is a condition in which the pressure in a non-potable system is greater than the pressure in the potable water distribution system. Superior pressure will cause non-potable liquids to flow into the potable water distribution system through cross-connections.
Q	What is a backflow prevention assembly?
A	A backflow prevention assembly is an approved, testable assembly which uses valves, in different configurations, to prevent potential contaminates from flowing into the potable water system.
Q	What assemblies are approved for installation in the City of Lynchburg?
A	Air Gap Reduced Pressure Principle Assembly (RPZ) Reduced Pressure Detector Assembly (RPDA)
Q	How do I know if I need a backflow prevention assembly?
A	A City of Lynchburg Compliance Specialist will inspect each building for cross connections and existing backflow assemblies. The Compliance Specialist will mail a “Notice of Compliance or Non-Compliance” letter. This letter will outline the actions you will need to take.
Q	Where should a backflow prevention assembly be located?
A	The backflow prevention assembly must be located as close as possible to the potable water service connection, but it must remain on private property.
Q	How is an assembly approved?
A	An approved backflow prevention assembly has gone through an approval process at the Foundation for Hydraulic Research and Cross-Connection Control at the University of Southern California. This is a two-step process of laboratory tests and a twelve-month field test. Only assemblies successfully completing the entire testing procedure are recognized by the City of Lynchburg as approved backflow prevention assemblies.
Q	Why do backflow prevention assemblies have to be in a heated enclosure?
A	A backflow prevention assembly has to be in a heated enclosure because of freezing temperatures and protection against vandalism. RPZs have to be installed above ground because of the relief port and must be heated in the winter to keep the assembly from freezing and failing to function properly.
Q	Why do backflow prevention assemblies have to be tested periodically?
A	Mechanical backflow prevention assemblies have internal seals, springs, and moving parts that are subject to fouling, wear or fatigue. All backflow prevention assemblies have to be tested periodically to ensure that they are functioning properly. A certified tester with properly calibrated gauge equipment would perform this test.
Q	What if my backflow prevention assembly is leaking?
A	It is the responsibility of the customer to ensure that the backflow prevention assembly is in proper operating condition at all times. If you discover your backflow prevention assembly is leaking it is your responsibility to call a certified tester to repair the assembly as soon as possible.
Q	Who is responsible for the testing and maintenance of the backflow prevention assembly?
A	Backflow assemblies must be tested when they are installed and at least annually. The City of Lynchburg sends notices to customers reminding them when the annual test is due. The customer must contact a certified tester from the City of Lynchburg’s tester list to perform the test. The test must be submitted to the Department of Water Resources. If the repair work or maintenance is performed on a backflow prevention assembly, a certified tester must retest the assembly immediately after repairs and submit test reports to the Department of Water Resources.
Q	Who should I contact for more information?
A	The City of Lynchburg, Department of Water Resources will be happy to answer your questions. Please feel free to call 434-455-4261 to speak with the Compliance Specialist.