Bid a job the other day were the customer requested that I use the sillcock as the point of connection. OK fine. used my handy dany tester and we have 15GPM @40 PSI. (Its a small two zone area with no real potential of expansion.) Before I agreed to install such a system I check to make sure that the building has backflow prevention. It has a 3/4" RPZ for all water needs in the building. But its about 100' away from the Point of connection mentioned.The pipe goes veritcal from the sill **** about 15' into the ceiling before traveling to the RPZ. Recently I spoke to the plumbing inspector for the area and confirmed that the building has to have a RPZ to be legal with an irrigation system. My question is, would you do such a thing? or would you insist on a $400.00 RPZ install just for the irrigation system? When I handed him my quote he asked about it. I told him that he would be legal and that I designed it as he requested. He mentioned that some other contractors want to put in the RPZ for $400.00- I assume its an easy upsell on such a small system if they did'nt know any better. Your thoughts Please????