Question
I have a Rainbird system. Everything works ok,all zones come on and shut off when they are supposed to. Problem is water seeps out of one sprinkler in zone 1 contiually when no watering called for. Is this the fault of the control valve for that system or the sprinkler head itself?

Answer
There could be a couple of things.  One is that if the sprinkler with the seepage is lower than the rest of the system, water will drain out of the sprinkler that is in the lines when the valve shuts off.  This is called low head drainage.  You can purchase a check valve to install under the sprinkler, or some companies make sprinklers with built in check valves.  If this is not the issue, it could be that your valve is "weeping", and needs to be disassembled and the internal parts cleaned out or replaced if worn or torn.