Leaking sprinklers when system is off

I have 2 zones in my back yard and both of them have sprinkler heads that have water leaking out of them even when the system is off.

The zone in the front yard does not have this occurring.

The only thing that has changed recently was I removed an old unused valve that was T'd in to the supply line that feeds the back yard and capped off the vertical piece of pipe that is T'd in to the supply line.

How can these 2 separate zones be pressurized when turned off?

Do you have electric solenoid valves controlled by a timer or manual ball valves?

Solenoid valves can leak a little and will result in water seeping out sprinklers when the zone is shut off. If this is the case sometimes disassembling the valve and flushing out any dirt in the diaphragm can work. Otherwise replace the valve. Manual ball valves can leak too but its much less common.

The other problem can be low head drainage. When the system turns off water can seep out of the sprinkler heads at the lowest elevation. The amount of seepage is limited to the water in the line above the head elevation. If the water seeps for a long time and never slows down this isn't likely the problem.

If you have solenoid valves I would assume when you removed the unused valve some debris got into the line upstream of the valves and is causing them to seep even when closed.

Thank you for your reply. I believe you nailed it. I have electric solenoid valves controlled by a timer and I'm pretty sure I got some dirt in the line while cutting out the old valve.

I've never disassembled a valve before for flushing. Is it a difficult job for a amateur like me to complete?

Is it possible that if I turned them on and let them run for an hour or so that the dirt would purge on it's own?

Running the valves for a long time probably wont fix anything, you will need to take the top off the valve to do this. Not difficult but just pay attention to how everything came apart and get it all back together properly.

1) Shut off the water supply upstream of the valves and open a valve to bleed off the pressure.

2) If you have a Jar Top Type valve you can just grab the top of the valve ( that part that the solenoid screws into) and unscrew it off the valve body. If your valve has screws holding the top on just undo the screws and lift the top off. You can unscrew the solenoid from the valve top if necessary.

3) Carefully observe the alignment of the diaphragm and spring inside the valve and make sure you don't get any more dirt inside the valve. Pull out the diaphragm and rinse out the valve body, top and diaphragm with a hose and clean out any dirt. You can also crack the upstream valve a bit and flush out the line upstream of the valves with the tops off. Be careful to not make things worse by getting more dirt into the valve when you do this.

4) Assemble the valve the same way it came apart, be careful not to over tighten screws and strip out the body.

5) Turn water back on and check for leaks, if you put your ear right against the valve you can usually hear a small leak.

If you rip the diaphragm or find it damaged you can just go buy a new valve exactly matching what you have and put the new top on the old body.

Hope that helps

John

Very helpful John. Thanks !