Question on use of one or two PVB's

Hi all..

I'm starting to think about what I need to do from a landscaping point of view after our yard was torn apart last summer for a remodel.. I want to start with the front yard first since it will affect the curb appeal (and its much smaller besides that). To that end, I need to tell you right off that I'm in the Los Angeles area so no freeze issue to worry about.

Now, I've got a single ball valve that controls water to my entire front/rear sprinker setup.. Yesterday I ripped up the old valve system and cut off the dead lines (some of the old lines were buried under part of a new slab -- long story). So, I was able to run some compressed air through some of the other lines to verify what was what. Anyway, I picked up a Wilkins 720A (3/4") PVB to use in the front yard but am curious about one thing -- elevation..

Our back yard sits about 2.5-3' higher than the front (gently sloped) so if I want to use a single PVB for the entire front/rear sprinkler system I'd need to mount it near the current ball valve and mount it up about 4-5' off the ground in plain site of the front yard.. Not sure I like that idea from an astetics point of view.

So -- can I use two PVB's -- one in the front yard for that segment of the system and another PVB in the very rear (at the high end of the lot and above any raised bed garden boxes) of the backyard before the water is distributed to any sprinklers or drip systems? Both are still tied to the same ball valve ultimately -- located in the front yard.

IF I go with two PVB's, I've got a single hose bib on the same long line that runs to the back yard (from the front ball valve) and that faucet would be before the backyard PVB -- but perhaps covered by the front one? Not sure.. My hunch is it wouldn't be since the front yard PVB would be on the other side of the tee past the ball valve -- unless I put the front yard PVB just after the ball valve.. Hmm..

Anyone see any issues with using two PVB's beyond the obvious extra cost? Our local code follows California Plumbing Code and I was told that I need to use, at a minimum, an Anti-Siphon valve or PVB.

Thx!

Well.. I installed my first PVB a few weeks back and have it at least 12" above the highest sprinkler (making it ~18" off the ground). Had I wanted to use it for the backyard as well, it would have required it to be mounted closer to 4.5' off the ground -- looking rather odd IMHO. So, for now I've got the single but will move to a double system once I start working in the backyard.

If you want a single valve, run the supply back to the back yard, put a PVB on top of the hill, and feed back out to the front. Otherwise, settle for 2 valves.

Pvb

Install on PVB for the front and then run a separate line, not from the front PVB to the rear and install the second PVB. Do not install the 2 PVBs in series, you will degrade the performance of the rear system.

Thanks for the reply.. I guess I might have to re-pipe my rear stuff if I can't (or shouldn't) have two PVB's in series.. My front one is working like a champ so far.. Thanks for the suggestions!