Gravity plays a large factor in any irrigation system. If one of your sprinkler heads is positioned lower than the others (such as at the bottom of a hill or incline), standing water in your pipes will flow there when your system is turned off. If there is enough water, it can build enough pressure to push up through the head and cause the head to trickle or leak.

There are two possible solutions. The first is to replace the head with one using Rain Bird's patented Seal-A-Matic (SAM) technology. This will prevent water below a certain pressure (such as standing water not under the operating pressure of your system) from entering the sprinkler head, avoiding leaks.

If a SAM version of your head is not available, you can also install a check valve. This works similar to a SAM, but installs in your pipes, and also prevents the flow of water below a certain operating pressure.