Annual Backflow Valve Testing

Below are some commonly asked questions about the required backflow valve testing.  More information about the County Cross Connection Control and Backflow Prevention Program can be found HERE.

What is a backflow valve (a.k.a., backflow prevention assembly)?  

A backflow valve prevents water in the sprinkler lines from flowing back into the main water supply.  Many lawn sprinklers have a similar valve for the same reason.

Does every house with a sprinkler system have a backflow valve?  

No, but most of ours do.  Fairfax County started requiring them in February, 2022.  If your house passed inspection before then (i.e., 11301-11317 (odd only) Reston Station Blvd and 1860-1870 Michael Faraday Drive), you do not have one and do not need the test.

How often does the backflow valve have to be tested?

Fairfax County requires backflow valves be tested annually.  Our homes are in a map grid whose inspections are due in May.

What does a backflow test entail?

This article gives a pretty clear explanation of what to expect.  The test takes about 10 minutes.

How do I find someone to do the test?

The county website has a list of authorized vendors who can do the test.  Some companies are more responsive than others.  Some may no longer be doing testing.  Be sure to confirm that they will also file the paperwork for you.

How much does the test cost?

The price varies wildly. You may be able to get a group discount if you get some neighbors to do it at the same time.