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Sunday, July 15th 2018, 9:13pm

No backflow preventer?

We just bought a house a couple months ago and I am trying to turn on the sprinkler system. I found a valve in the front yard near the water meter:

However I was not able to find a backflow preventer outside or in the basement. I turned the valve on slowly and the sound of water running through the house did stop and the sprinklers seem to be working fine. Is it possible the house doesn't have a backflow preventer?

The house was built in 1999 in Fairfax County, Virginia.


Supreme Member

Posts: 5,331

Location: Metro NYC


Monday, July 16th 2018, 5:20pm

There is no irrigation backflow preventer showing in your photo. There is showing a "Dual Check Valve" device, which is a just-in-case device commonly seen installed just downstream of water meters. It has no value as proven protection. It is only a backup device. Primary protection cames from either a Pressure Vacuum Breaker or a Reduced Pressure Zone device, those commonly known by the acronyms PVB and RPZ

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