What is an RPZ backflow preventer?
This is an RPZ backflow preventer on the main water line in a Loudoun County basement, old and corroded, right before we replaced it. Its job is to make sure water from your house can never flow back into the public water supply.
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From one of our jobs
An old RPZ on a Loudoun County main line
Right now: Look under the valve. A steady drip from the bottom vent means a part inside has failed.
RPZ stands for reduced pressure zone. Inside are two check valves with a relief valve between them. If pressure on the street side ever drops, the relief valve opens and dumps water out the bottom instead of letting it run backward into the main.
That’s why your water utility wants it tested every year, and why a dripping RPZ is worth a call. A little discharge after a pressure swing is normal; steady dripping means a check valve inside isn’t sealing.
Quick answers
What people ask about RPZ backflow preventers
What is an RPZ valve?
A reduced pressure zone backflow preventer. It sits on the main water line and stops water from your home’s plumbing from flowing back into the public supply.
Why is my backflow preventer dripping or spitting water?
A short burst after a pressure change is normal. A steady drip usually means one of the check valves inside is dirty or worn and needs a rebuild.
Do I need my backflow preventer tested every year?
If your water utility or county sent you a letter, yes. Loudoun Water and Fairfax Water ask for a yearly test on homes with one, filed by a licensed tester.
Can a backflow preventer be repaired, or does it need replacing?
Most can be rebuilt with new rubber and springs. A body that’s corroded through, like this one, gets replaced.
Who tests backflow preventers in Northern Virginia?
Call SwiftPro at (703) 997-9757. We test, tag and file the results with your water utility, and repair or replace the preventer if it fails.
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What it costs
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SwiftPro Heating, Cooling & Plumbing
4230 Lafayette Center Dr N, Chantilly, VA 20151
44679 Endicott Dr, Suite 211, Ashburn, VA 20147
SwiftPro Plumber & Water Heaters
4200 Lafayette Center Dr, Suite N, Chantilly, VA 20151
Virginia Class A contractor license #2705192276