Cross-Connection Control & Backflow Prevention
Overview of Cross-Connection Control and Backflow Prevention
Providing abundant drinking water of exceptional quality is the core of Fairfax Water’s mission. Therefore, it is essential to safeguard the water after it leaves the water treatment plants. In order to fulfill this mission, Fairfax Water maintains a Cross-Connection Control and Backflow Prevention Program. The goal of the program is to prevent the backflow of contaminants or pollutants into the Fairfax Water potable water system.
What is a Cross-Connection?
A cross-connection is a link between potable water pipes to unsafe, unknown pipes and/or liquid.
For example, a garden hose attached to a hose bib with the outlet end submerged in a pond or swimming pool. If Fairfax Water’s supply pressure drops, the water from the pond or pool can be suctioned into the drinking water supply. This water can contaminate the customer’s water system as well as the Fairfax Water potable water system, possibly exposing nearby customers.
What is Backflow?
Backflow is the undesirable reversal of the normal flow of water or other liquids, mixtures, or substances into the drinking water supply.
This occurs in two ways.
- Backsiphonage: When a drop in Fairfax Water’s supply pressure creates a suction effect drawing water out of a building, house, or other private plumbing system back into the Fairfax Water potable water system. Real examples that could lead to decreased supply pressure include opening or closing a valve, flushing a fire hydrant, or a water main break.
- Backpressure: When a building, house, or other private plumbing system with greater pressure than Fairfax Water’s supply pressure pushes water from the building, house, or private plumbing system back into the Fairfax Water potable water system. This can occur in a pressurized system with booster pumps, chemical feed pumps, boilers, elevated storage tanks, or recirculating systems.
How is Backflow Prevented?
Preventing backflow is a matter of avoiding the reverse flow of unwanted substances into the drinking water by using special plumbing devices and practices. Preventing backflow is accomplished by requiring physical plumbing methods (air-gaps) or requiring the installation of mechanical back flow preventers designed specifically to prevent backflow within certain customer premises.
About Fairfax Water’s Cross-Connection Control Department
Fairfax Water operates its Cross-Connection Control and Backflow Prevention Department in accordance with the Virginia Department of Health’s Waterworks Regulations necessary to meet the standards established by the Safe Drinking Water Act. This is done by coordinating and operating joint programs with Fairfax County Land Development Services and the City of Fairfax Fire Department & Code Administration. Fairfax Water, Fairfax County, and the City of Fairfax are committed to protecting the public water supply.
Specific details regarding program requirements can be found in the following document:
The operation of the joint program includes:
- Determining which sites require installation of a backflow preventer based on hazard identification
- Surveying premises to determine the presence of actual or potential hazards
- Maintaining records of all customer backflow preventers
- Administrating and enforcing backflow preventer testing and inspection requirements
- Issuing fire hydrant use permits ensuring compliance with backflow prevention requirements
- Facilitating public outreach programs for education about cross connection control and backflow prevention
If you have specific questions regarding the Fairfax County Building Code, program requirements, test report submissions, inspections, or compliance, please visit the Fairfax County Cross Connection Control and Backflow Prevention website.