The Loudoun Water Cross-Connection Backflow Program is responsible for protecting the water distribution system from potential hazards caused by cross-connections of non-potable water systems.  Loudoun Water is committed to ensuring tap water is safe to drink, which according to Federal and State regulations, requires backflow preventers be tested annually by a certified tester to make sure it is adequately working. Please call us with questions: 571-291-7880

Backflow prevention protects both the customer’s drinking water pipes in their home as well as the water mains in the streets. Otherwise, if a drop-in pressure occurs, any connection to a non-potable source could be siphoned back into the customer’s home or Loudoun Water’s service line, which is dangerous. The only way to prevent such incidents from occurring and to maintain safe drinking water is to use a backflow prevention device that is correctly installed and maintained properly.

What is a cross-connection? 
A cross-connection is a temporary or permanent connection between a potable (drinking) water supply and a non-potable source (fire suppression system, irrigation system). 

What is backflow? 
Backflow is the undesirable reversal of the flow of water from its intended direction. Backflow is dangerous because it can allow drinking water in plumbing systems to become contaminated and unusable. There are two types of backflow

  1. Backsiphonage: When a drop in Loudoun Water’s system pressure creates a suction effect drawing water out of a building, house, or other private plumbing system back into the potable water system. (ex. water main break, hydrant flushing.)
  2. Backpressure: When a building, house, or other private plumbing systems with greater pressure than Loudoun Water’s system pressure forces water from the building, house, or private plumbing system back into the potable water system. (ex. pressurized system with booster pumps, chemical feed pumps, boilers, elevated storage tanks, or recirculating systems.)

As a homeowner why do I need a backflow prevention device?
Backflow devices are designed to prevent contaminated water from being mixed with the drinking water inside your home, as well as the public water supply. An approved backflow prevention device is required for all fire suppression systems and irrigation systems.

What is an “approved” backflow prevention device?
A physical means (air gap) or mechanical device that has been tested and approved by the American Society of Sanitary Engineering (ASSE).

Fire Suppression System
State Building Code or International Fire Code dictate when residential structures require fire suppression. Some developers offer fire suppression as an option. Stagnant water within the fire line has the potential to be siphoned back into your homes water supply without the proper protection in place. It is required by Federal and State regulations that this device be tested when installed and annually by a certified tester to ensure it is working properly. 

Are there special requirements for Private Booster/Fire Pumps?
Premises having booster pumps or fire pumps connected to the waterworks shall have the pumps equipped with a pressure sensing device to shut off or regulate the flow to prevent a reduction of pump suction line pressure from the potable water system to less than 20 psi gauge.

Underground sprinkler systems
System water can become contaminated from the use of lawn care chemicals and from other hazardous materials. This water has the potential to be siphoned back through the sprinkler head and flow back into your homes water supply, which could be harmful to you and your family. It is required by Federal and State regulations that this device be tested when installed and annually thereafter by a certified tester to ensure it is working properly. If the homeowner chooses to not use the irrigation system and avoid annual testing, the system must be cut and permanently capped by a certified irrigation contractor or plumber. 

As a homeowner that has one or more of these connections, what are my responsibilities? 
Federal and State regulations, requires backflow preventers be tested when first installed and annually thereafter by a certified tester to ensure the device is working as intended. The backflow test results must be provided to Loudoun Water. If a device is removed and reinstalled for any reason, that device is required to be retested following reinstallation/relocation (ex. Irrigation device removal for winterization and reinstallation of that same device the following year.)

Who is responsible for arranging testing of a backflow prevention assembly? 
Owners are responsible for arranging testing of a backflow prevention assembly. (With new structures, this is typically the contractor)

Who maintains my backflow prevention assembly(ies)? 
Owners are responsible for maintaining devices if any signs of damage are evident during annual testing or between testing events. The device should always be operational to avoid cross-connection contamination of the internal house plumbing and/or the water service from the Loudoun Water main. 

What if my backflow prevention assembly fails the test? 
A notice will be sent to the owner of any building or structure that is found to have devices in violation of the Loudoun Water Cross-Connection Backflow Program. Devices found to be in non-compliance shall be repaired or replaced, then retested by a certified tester at the customer’s expense within 30 days of notification by Loudoun Water. If a device is removed and replaced with a new device, this must be completed by a master plumber.

What happens if I don’t have my assembly tested? 
The annual testing of a backflow assembly confirms from a certified professional that the device is operating properly. The risk of contamination potentially impacts the health of the people in your household as well as other Loudoun Water customers. Owners who do not have properly operating and maintained backflow prevention assemblies will be in non-compliance. Loudoun Water may disconnect and discontinue the water service to any customer who poses a risk to the drinking water supply via an unprotected connection. 

Who is responsible for submitting the sheet to Loudoun Water? 
The certified tester must complete the test form or online webform. If filling out a paper test sheet, the certified tester must provide the test results to the owner and Loudoun Water. Test sheet results can be sent to Loudoun Water by mail at 44771 Loudoun Water Way, Ashburn, VA  20147 or by email to Online webforms are automatically emailed to the owner and Loudoun Water.

Other Tips to Avoid Backflow:
Common types of cross connections in homes include:

  • Garden hoses and hose bibs: If an insecticide or herbicide dispenser is attached to a garden hose, a pressure drop can cause chemical-laden water to be pulled from the hose and into the house water supply.
    • Avoid submerging a garden hose into a bucket, pool, spa, tub or sink.
    • ​Always keep the end of a hose away from possible contaminants.
    • Always have a backflow prevention device on your garden hose when putting on a spray or cleaning attachment.
  • Swimming pool or hot tub: If filled with a hose submerged in the water, pool water can be drawn back into the hose and into a house’s water supply.

For more information about backflow preventers and water supply protection, visit the International Code Council's website. Please see the Virginia Department of Professional and Occupational Regulation website for licensed certified testers** (Enter search terms like name, license number, address, and license type). You can also use the Advanced Search form (Enter search terms like zip code, city, state, Board (Board for Contractors), License Type (Backflow Prevention Device Worker) **Note: DPOR website does not provide contact information for licensees.

Questions/Concerns? Contact Us
Loudoun Water
Cross-Connection Control & Backflow Prevention Department