Please describe your system and the problem in more detail. Elevation differences from your valves to your heads could cause this problem. Can you see the leaking from the heads or just the evidence of it? Does the the entire zone drain out after each irrigation cycle? Aloha

I have a drip irrigation system with two lines. One waters the trees and the other waters the shrubs. The drippers that are leaking are the last two on the tree line. I have 6 active drippers on the tree line and have 4 plugged. The two at the end are plugged to stop water from running out constantly and the other two are plugged because the trees appear to be getting plenty of water from the surrounding shrubs.

My lot is perfectly flat, in AZ. When I have dripper heads on the last two I can see water flowing. Right now I have plugs in both and there are calcium deposits around them indicating that some water is getting out. Not as much for sure. I run the sprinklers early in the morning but usually check plants and drippers just before sundown. I don't think the entire zone drains out, there is water running through the tubing every evening unless I have them plugged.