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.

  1. 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.

  2. 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.

 
Contact Us

Fairfax Water
Cross-Connection Control & Backflow Prevention Department
Phone: 571.722.7653
backflow@fairfaxwater.org

FAQs

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I received a Notice of Disconnection of Water Service for a “Cross-Connection Violation” Why have I received this and what do I need to prevent my water from being shut off?

If you have received a Notice of Disconnection of Water Service for a “Cross-Connection Violation” it is because Fairfax County Land Development Services has notified Fairfax Water of a Cross-Connection violation that has yet to be resolved.  This could be because you have not submitted required annual test reports for backflow assemblies or have a hazardous plumbing configuration that is in violation of the Fairfax Water Cross‑Connection Control and Backflow Prevention requirements, Virginia Construction Code, and/or the Virginia Department of Health Waterworks Regulations.

To prevent your water from being shut off, please contact Fairfax County Land Development Services as soon as possible at:  LDSCrossConnectionProgram@fairfaxcounty.gov

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Does my underground lawn sprinkler system require a backflow preventer?

Yes. All underground lawn and garden irrigation systems are required to have backflow prevention assemblies installed and routinely maintained. State law requires such assemblies to be tested at the time they are installed and yearly thereafter, as well as any time they are repaired or replaced.

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Where in my home or business are backflow prevention devices typically found or required?

If you have a toilet with a tank on the back in your home or business, it contains a valve to fill the tank every time you flush. The fill valve, or “ballcock,” is equipped with an approved backflow prevention device that prevents any water in the tank from being siphoned back into the pipes of your house (anti-siphon). Plumbing codes require all water outlets to be equipped with a backflow prevention device to prevent contamination or pollution of the drinking water.

Therefore, all sinks have a space between the end of the faucet and the flood level of the sink called an air gap. Some sinks typically found in commercial businesses, such as a mop sink, are equipped with a backflow prevention device called an atmospheric vacuum breaker installed on the faucet.

All hose bibs (sillcocks) are required by code to have a special backflow prevention device installed called a hose connection vacuum breaker. This device prevents water in the hose from flowing backward into the pipes of your house.

All commercial fire-sprinkler systems are required to have backflow prevention devices installed.

In other types of commercial and industrial businesses, it is necessary to ensure the safety of Fairfax Water’s potable water system by requiring the installation of backflow prevention assemblies in the main water-service line to certain types of buildings. The types of backflow prevention devices installed at these locations can range in size from ¾ inch to 10 inches in diameter and cost anywhere from a couple hundred dollars to tens of thousands of dollars to purchase and install.

These are just a few of the examples of where one might find backflow prevention devices in either a home or business.

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What is an “approved” backflow prevention device?

A physical means or mechanical device that has been tested and approved by a nationally recognized laboratory, organization or institute, such as the Foundation for Cross-Connection Control and Hydraulic Research, or the American Society of Sanitary Engineering.

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What is a backflow prevention device?

Any approved device, assembly, method, or type of construction intended to prevent backflow into a potable water system.