I've spent the last few days trying to determine the cause of my sprinkler system malfunction; I'm hoping someone here has some insight, because I'm at my wits' end!

A bit of history, to setup the story: I have a system that was installed in May of 2005 that consisted of a Hunter control box, RainBird valves and miscellaneous sprayers and sprinkler heads by RainBird and others. The system gave us no problems up until the last year. It runs off of a deep water well (700-800') with a booster pump and 1200 gal water storage tank.

The system appeared to leak somewhat (not visible) over the last year. I could tell, because when the backflow valve was shut off, the well booster pump would not run. With the backflow valve turned on, the well booster pump would kick on and off every few minutes. I figured it was a small leak, and I'd wait until I could see a wet area to dig into the problem. Then, last July, we had lightning strike somewhere nearby and knock out our Hunter control box. I replaced it with a RainBird control box, which (personal opinions aside) worked fine until the last 2 weeks.

In the last couple of weeks, our sprinkler system started making multiple zones turn on at the same time. In fact, it almost seems as though all zones are turned on, but there's just not enough pressure to see the effects as much at each zone. I took a look at the problem and decided it had to be one of two things: 1) either the control box had gone bad again and was turning on multiple zones at once, or 2) all the valves were stuck open. Keeping it simple, I attempted to fix #1 first. I put a brand new Orbit control box on the system (which has much better controls, but I digress...). The Orbit showed the same symptoms -- multiple zones turning on at once, even when manually attempting to operate only a single zone.

Zone #1 always seems to have the most water pressure going to it (when multiple zones are running), so I decided to start digging there. I finally found the valve box for Zone #1, and I cleaned off the outside of the valve. It doesn't look like the valve is leaking at all, nor could I see any leaks from the pipes. So, I changed out the solenoid with a brand new one from RainBird. Still no joy; that didn't change anything.

So, here's where I'm at: it looks like either all my zone valves have catastrophically failed, or there's something else I'm missing. The wiring for the control box has 7 zones plus a common wire and a master valve wire. I've checked the pressure at the well booster pump; it was at 63psi, and I lowered it back down to 50-52psi, which is normal city water pressure, I'm told. I'm at a complete loss as to what is going on, and I dread the thought of having to locate and dig up 6 more valves to check them. :(

Any help would be much appreciated! Thanks in advance.