I recently purchased a new home and began working on the landscaping and drip irrigation system. Aside from the many leaks, I discovered that anti-siphon valves had been installed below ground, in a box. Worse still, my property has extreme grade changes and 3 of the valves were watering up-hill (as much as 15-20 feet), so water was spilling out of the valves the entire time they were running.
So, I had a plumber install a RPZ back-flow prevention device and am now going to work on the valve manifold.
My question is, do I need anti-siphon valves now that I have the proper back-flow device? Will the water stored in the uphill lines after shut-off cause an issue for the valves (back pressure)? Should I add a check valve to these valves?