RPZ valve ... never heard of it until today

Today I was inquiring about irrigation parts and somebody on the east coast asked about my RPZ valve. I've never heard of an RPZ valve out here in California.

I've been a DIY type for years, and have helped lots of friends and relatives with their houses as well, and I just haven't seen anything like what is pictured here at a residence:
http://www.sprinklerwarehouse.com/Reduced-Pressure-Zone-Assemblies-s/8412.htm

We do have vacuum breakers on our hose bibs with a set screw, and our automatic sprinkler valves have anti-siphon devices (usually plastic), but that's all I've ever seen or worked on. Am I just oblivious or are these fancy RPZ devices not required in California?

The RPZ BFP can be installed in the incoming water line and be located in a control box beneath the surface. I do not know what California's requirements are, but from what I know about the state's concern about environmental issues, I would be surprised if they are not required along with annual certification of performance.

In CA, all commercial buildings ( apts, condos, etc) must have all water supplies protected by an RPZ valve. SIngle family homes have somewhat less resrictive requirements at this time . Domestic water ( the house) must have bibbs, pull out kitchen spouts, RO filter drains, hand held showers, , dishwasher drains, etc. protected by an approved backflow device. Sprinkler systems move up the scale to anti-siphon valves or pressure vacuum breakers. I would not be surprised to see RPZ creep into the code soon enough.