If you have a sprinkler system and an assembly above ground near the point of connection, there is a good chance this is what it is. The pressure vacuum breaker is the workhorse of residential irrigation protection in this part of Colorado.
It is a spring-loaded air inlet and a single check valve in one body, with shutoff valves on both sides and test cocks so it can be certified. The spring is the important part — it holds the air inlet closed under pressure and opens it the moment pressure drops, rather than relying on flow the way an atmospheric vacuum breaker does.
That difference is what makes it practical. A PVB can sit under constant pressure all season, and valves can be installed downstream of it, which means one assembly protects the whole system instead of one per zone.
What it does not do
It stops backsiphonage. It does not stop backpressure. Anything downstream that can push — a booster pump, a chemical injector, an elevated line — is outside what a PVB is built for, and those connections take a reduced pressure assembly instead.
It also has to sit above the highest sprinkler head on the property, typically by at least twelve inches. On sloped ground that is a design constraint, not a detail — a head uphill of the assembly is not protected by it.
Where you find one
Irrigation and lawn sprinkler systems, first and foremost. Also ponds and water features filled from the building supply, where there is no pump pushing back the other way.
Testing and freezing
A PVB is a testable assembly. Colorado requires it to be certified once a year by a certified technician, with the report filed directly to your water provider. The test is done in the spring with the system charged, which makes it the same trip as your startup.
It also sits above ground with water standing in a brass body, which is the other thing worth knowing about it. A hard freeze splits the body, and a replacement costs several times what a blowout does.
Schedule a backflow test or call 970-835-9661