Back Flow Prevention

Troubleshooting Sprinklers & Irrigation
1

Hello all,

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?

Thank you,
Pete

2

Looking to learn from others but typically my sprinkler heads will drain excess water from the lowest point in the zone when they shut off. I only have a backflow prevention valve (required by the city).

3

We do not have and are not required to have an anti-siphon or back-flow (we have irrigation instead of culinary). I put an excess of king drains, so it drains before the lowest point. A relatively small amount drains at the lowest point. I definitely want my drained so they hopefully will never freeze. I do not think back pressure would cause an issue unless it can ever freeze.