Lawns - Leak in underground sprinkler system

I've just recently noticed that I've got a leak in one zone of my sprinkler system. I don't know the layout though of the underground pipes that deliver the water to the sprinkler heads.

Is there some way that I might be able to help isolate precisely where the leak might be instead of just digging up the entire yard looking for it?

is there an isolated wet area or are your heads weeping?

depending on your soil you might be able to cap off the heads which would apply full pressure at the leak. the looser the soil the faster it will show up

depending on your soil you might be able to cap off the heads which would apply full pressure at the leak. the looser the soil the faster it will show up


Ahh, that's a good idea. When I think about it, I noticed this particular zone seemed a little low on pressure back around in November, but here recently after I noticed a lot of water seeping out around the hedges, I've determined that most of the sprinkler heads in the zone are receiving water (just low pressure) but there are about 2-3 heads that are getting almost zero pressure. Now that would generally point to the line in between the last one that's getting low pressure and the first one that is getting zero, but as I said, I'm not sure how the underground piping is laid out since I'm not the original owner of this place.

Thanks for the idea to cap off the lines...I believe I'll give that a try this weekend.

Just wanted to provide an update. I bought plugs and PVC extensions to cap off all the risers on the zone. Yup, there was a pretty good size leak. The water meter was flowing at almost the same rate as if all the sprinklers were active.

Now begins the fun. This weekend I get to start digging up the ground to find the leak. I figure if it is close to the valve I'll go ahead and replace that also; all of my valves are inline type.

let it run awhile, maybe 10 minutes and it might perc to the surface

I wanted to give everyone an update and the conclusion to this problem.

As I mentioned in my previous post, I decided to give the advice here a try and I capped off all of the sprinkler heads. I quickly began to notice a huge puddle forming in the area. To make a long story short after digging down 2 feet I found the leak. The PVC had literally been ripped apart at a T joint. I spotted the culprit - it was what looked like a very strong root from a tree. I was unable to rip it apart with my hands so I got out the portable saw. After cutting into a bit I notice metal coming off of it and stopped immediately. Well, I tried to pull on it, and was able to loosen a great deal and managed to pull it out of the ground. It was no root, but rather some 1/2" diameter iron rod that was bent into a U or V shape. It was only about 2 feet long, and it baffles me why this was in the ground in the first place. It was not serving as a ground rod or anything similar, but from where it was located, I imagine the ground contracted sufficiently for it rip that PVC like it did.

Repaired PVC and now have 40 psi across that zone.

I utilized this same technique on another zone that I have long suspected had problems with it since we moved here. Yup, ANOTHER leak. This zone was for our long distance rotor sprinklers, which we had 3 of on this zone. So again, I capped them off and let it run for a while. This one took a little while to locate, but after raking away some leaves I found the leak yet again. The damage to this PVC was not as bad. It had simply come apart and it looked like someone had previously tried to repair it in this exact same spot because there was a PVC coupler on the line. I imagine they didn't cement it properly. So, I fix that one quite quickly and lo and behold this zone now has 80 psi of pressure.

I also learn this zone in fact has 4 rotor sprinklers on it, not 3 like I had previously thought. Can you imagine? Ever since I first lived here this particular zone has been leaking. So I replace the old worn out 4th sprinkler with a brand new rotor and now my backyard is getting proper precipitation distribution.

I am very happy to have these leaks fixed, but of course it rather angers to me to remember how much money I have thrown out in the form of excess water bills that I could have saved. Well at least I've found the leaks and fixed them.

Thanks everyone.

glad everything worked out for you and i must say it's great that you got back with the results. thanks for posting the outcome. :thumbup:

I noticed that "kerry" wondered at the beginning of this post whether the heads were weeping or not. In my case, the sprinkler heads in one of my zones are weeping. Also, there are no trees anywhere on my property. I'm wondering if there's a problem with the valve for that zone, but I wanted a bit more feedback with regard to that angle before proceeding (seeing as how the problem for the original person posting ended up being fairly isolated). Any ideas? Thanks!

some valves have a manual bypass. if yours are so designed be sure it is all the way off. also, the lowest head in the curcuit will weep until the lines are drained. if none of the above apply replace or rebuild the valve.

Is this something that can happen a few years after the system has been installed and no person has touched the valves since?