I have an irrigation system to install in a new subdivision I had the water dept. to come out and give me a psi and gpm test at the meter. It was 140 psi and 39 gpm they did remove the meter when they tested it so I dont know how much you would lose thru the meter? The meter size is 5/8. I normally use a zurn Wilkins 975xl 1 backflow and here we use pvc pipe I use schedule 40 at the backflow and psi 200 for the rest of the runs or zones. My question is do I need to install a pressure reducer and if so should it be installed on the downward side of the backflow and what would I be losing as far as gpm?