I have seven drip systems set up and I had been running them off individual battery-operated timers. Everything was working okay but it was a bit of a pain keeping all of them in batteries and programed. This year I decided to try to control all of them from a single timer that operates off AC power. I installed the timer and some Rainbird anti-siphon valves that I acquired somewhere over the years. Anyhow, the system works fine except that some of the valves continue to leak after they shut off. I found an instruction manual for the valves and it said that they should be installed at least six inches below the lowest sprinkler head. This wouldn't be practical on a couple of the branches so I'd like to replace those Rainbird valves with a decent valve that can be installed higher than the drippers. Also, it would probably be best if it were designed for the lower flow and pressure of drip systems. The systems are not connected to potable water so the anti-siphon feature is not necessary. Can anyone recommend a valve that will work for me. TIA!