Connecting irrigation to water main with pex homerun system

[mmilas]

Hi,

I have a very elementary question regarding connection of a frontyard and backyard irrigation/sprinkler system to my water main. I am in the process of planning an entire plumbing conversion in my 1950s california ranch style home (about 1300' sq) and would like to diagram an overall plumbing layout.

My water main output is a 3/4" valve, running galvanized into and throughout the entire house. My plan is to run 3/4" pex (or PVC) into the house. And connect the main to a 1/2" pex home run manifold system for distribution throughout my house.

My question is, how do I run PVC into my front and backyards that would eventually connect to a sprinkler manifold? Would I simply install a T connection from the 3/4" water main line somewhere in the crawl space and then run it out to the front and backyard? Or would I distribute the irrigation water through my pex homerun manifold?

I have a relatively steep hillside in the backyard so adequate water pressure is concern.


Thanks in advance.
Mike

[hj]

I think you will find that connecting an irrigation system to a house's 3/4" PEX, manifold or not, will create serious pressure and volume issues when it is running. Secondly, you will need at LEAST a "pressure backflow preventer" ahead of BOTH valve manifolds. The "smart" way to do it would be install a tee BEFORE the line enters the house. Install the BFP there then run a line to the front valves and continue the line to the rear of the house, either by going through the house or around it.

[mmilas]

Thanks! I appreciate you thoroughly answering my question.
Is running PVC into the house from the main (including the T for irrigation), then connecting it to PEX once in the crawl space rather then running PEX the entire way a correct and cheaper alternative to burying PEX?

[Gary Swart]

I'm quite sure PVC pipe is cheaper than PEX, especially when the connections are figured in. HJ is spot on about the BFP outside after the tee. BFP are supposed to be tested and certified each year, so it needs to have easy access. I know some places ignore the certification requirements, but not all do. There are several types available, you should check with you local irrigation supply house for assistance on the best one for your layout.