Backflow Prevention in Loudoun County: What the Requirements Are
Ajax Plumbing is backflow certified. Here is what Loudoun County requires, who needs a device, and what annual testing involves.
Backflow prevention is one of those plumbing requirements that commercial property owners and irrigation system users deal with regularly, and that most residential owners have never thought about until it comes up in an inspection or a service connection notice. Ajax Plumbing is backflow certified, which means we can install assemblies, perform the required annual tests, and submit test reports to Loudoun Water on your behalf.
This covers what backflow is, who is required to have a prevention device in Loudoun County, what annual testing looks like, and what happens if you skip it.
What Backflow Is and Why It Matters
The water supply system is pressurized so water flows from the main into your building. Backflow happens when that pressure relationship reverses, either because main pressure drops suddenly or because pressure at a connected use point rises above supply pressure. When that happens, water from your side of the meter can flow backward into the public main.
The hazard depends on what is on your side of the meter. A residential home with no irrigation system and no chemical treatment has low backflow risk. A commercial facility with a boiler system, chemical injection equipment, or a pool has significant contamination potential if backflow occurs. Irrigation systems can backflow fertilizers and pesticides into the supply. For this reason, Loudoun Water and the Virginia Department of Health require backflow prevention assemblies at specific cross-connections.
Who Needs a Backflow Prevention Device in Loudoun County
Loudoun Water’s cross-connection control program requires backflow prevention at:
- All commercial and industrial accounts — regardless of the type of business or use
- Any property with an irrigation system connected to the potable water supply
- Properties with boilers or cooling towers that use chemical treatment
- Properties with pools, spas, or fountains connected to the supply
- Healthcare facilities, food processing, and car washes — high-hazard classification requiring reduced pressure zone assemblies
- Multi-family residential buildings at the service connection
Single-family residential accounts without irrigation systems are generally not required to have assemblies beyond the standard hose bib vacuum breakers. If you have an in-ground irrigation system connected to your Loudoun Water service, you are required to have a testable backflow prevention assembly at the irrigation system connection.
Annual Testing Requirement
Testable backflow prevention assemblies must be tested annually by a certified backflow tester. The test verifies that the check valves inside the assembly are seating properly and that the relief valve on reduced pressure zone assemblies is functioning. The test takes about thirty minutes on most assemblies. Results are reported to Loudoun Water on a state-approved test report form.
If an assembly fails the annual test, it must be repaired or replaced before a passing test report can be submitted. Repairs to assemblies typically involve replacing internal check valves or O-rings. We carry common repair kits for major assembly brands and can often repair and retest in the same visit.
What Happens If You Skip Annual Testing
Loudoun Water tracks testing compliance by account. If a required annual test is not on file, Loudoun Water sends a notice. If the notice is not addressed, the utility can shut off service to the property until compliance is demonstrated. For a commercial account, that is a shut-off that stops operations. For a multi-family building, it affects all residents. The annual test is not a suggestion; it is a condition of service for accounts that require it.
We carry blank test report forms and submit directly to Loudoun Water after testing. You get a copy of the report for your records. If the assembly is overdue and you are not sure of the status, call us. We can run a test, check whether there is an open notice with Loudoun Water, and get you into compliance in one visit. See our commercial plumbing page and our backflow prevention installation page for related services.
Installation of New Assemblies
If you are adding an irrigation system, installing a boiler, or bringing a commercial property into compliance for the first time, we handle the assembly installation. The type of assembly required depends on the hazard classification of the use. Loudoun Water specifies the assembly type at the time of plan review for new construction or at the time of a compliance notice. We are certified to install double check valve assemblies and reduced pressure zone assemblies, which are the two types commonly required in Loudoun County.
Assembly installation on a new irrigation system typically takes two to three hours including the shutoff valve, isolation valves, and test cock connections that the assembly requires. We schedule the installation to coincide with the irrigation contractor’s connection work when possible so the job does not require two separate mobilizations.
Frequently Asked Questions
How do I know if my property has a backflow assembly on file with Loudoun Water?
Contact Loudoun Water’s cross-connection control program directly and ask for the compliance status on your account. You can also call us and we will check with you on the call. If an assembly was installed by a previous plumber and never tested, or tested years ago by someone who is no longer submitting reports, the account may show overdue even if a device is physically installed.
What is the difference between a double check valve assembly and a reduced pressure zone assembly?
A double check valve (DC) assembly is used for medium-hazard applications like irrigation. A reduced pressure zone (RPZ) assembly is required for high-hazard applications where a backflow event could contaminate the supply with chemicals, biological material, or other hazardous substances. The RPZ has an additional relief valve that discharges if the pressure differential fails. Loudoun Water specifies which type is required based on your use.
Can I get a free quote for backflow testing or installation?
Yes. Call 540-671-5417 or use our contact page. We give you a straight number for testing or installation before scheduling.
Do you serve commercial accounts in Leesburg and Loudoun County?
Yes. We cover commercial plumbing work across Leesburg, Ashburn, Sterling, Dulles, and the surrounding Loudoun County area from our base in Front Royal. See our commercial plumbing page for details.
Call 540-671-5417 for backflow testing or installation. Our contact page and project gallery are also available.