Why One Sprinkler Zone Stops Working, and How I Figure Out Which Problem It Is
Every year around the end of August the phone starts doing the same thing. Somebody notices one section of the yard going off color while the rest of it looks fine. They go out and watch the controller cycle through, and sure enough, zone four runs for its twelve minutes and nothing comes out of the ground.
The first thing most people assume is a leak. Something broke underground, water is going somewhere it shouldn't, and this is going to mean tearing up the lawn.
That's usually not what it is. And the difference matters, because the two problems cost very different amounts to fix.
Start with the question nobody asks
Before anything else I want to know one thing. Is water getting to that zone at all, or is the zone never being told to turn on?
Those are two completely different failures. One is plumbing. The other is electrical. And in my experience the electrical one is far more common, which is good news, because it's cheaper and it usually doesn't involve a shovel.
Here's the simple version of how the system works. Your controller sends a low voltage signal out to a valve. The valve opens. Water flows to the heads in that zone. Three parts, and each one can fail on its own.
If the controller isn't sending the signal, or the wire carrying it is broken, or the solenoid on the valve isn't responding, then the valve never opens. There's no leak. There's nothing wrong with your pipe. The zone is just never getting the message.
What late summer does to a system out here
The reason I get so many of these calls this time of year has to do with what our soil does when it dries out.
Clay expands when it's wet and it contracts when it's dry, and after a stretch of hundred degree days with no meaningful rain, it contracts hard. That movement pulls on everything buried in it. Wire splices that were fine in April get stressed apart. Fittings that were holding get pulled loose. Risers get shifted enough that a head stops seating right.
Then we finally get a real rain, the ground swells back, and something that was hanging on gives up.
I see this pattern all over the area, and it's worse in places with heavier clay and mature trees pulling moisture out of the ground. In Corinth I run into it a lot in the older neighborhoods where the systems went in with the houses and the wiring has been through twenty-some cycles of this.
None of that is a reason to panic. It's just what irrigation systems do here, and it's why a system that ran perfectly all spring can drop a zone in September.
What you can check before you call anybody
There are a few things worth ruling out yourself, and none of them require tools.
Check the controller is actually running the program.
Sounds obvious. But I have driven out to houses where a power blip reset the controller to a default schedule, or somebody bumped it to off, or the rain sensor is stuck engaged from a storm two weeks ago and is suppressing the whole system. Put it in manual and run the zone by hand. If it runs manually but not on schedule, your problem is the program, not the plumbing.
Look at the other zones.
If every zone is weak, that's a pressure or supply problem and it's a different conversation. If it's one zone and everything else is normal, you've narrowed it down a lot.
Walk the zone while it's supposed to be running.
Even if nothing is coming up, listen at the valve box. A valve that's getting the signal makes a soft click when it opens. No click at all points electrical.
Check whether anything happened recently.
New fence, new tree, somebody trenching for a dog fence or a gas line. I have found more cut wires from unrelated projects than I can count, and homeowners almost never connect the two events because the sprinkler didn't fail until the next time that zone was scheduled.
If you've been through all that and the zone still won't run, that's the point where guessing gets expensive.
Why I don't dig first
The reason I'm careful about this is that digging in the wrong place costs you twice. You pay for the excavation and you pay for the repair, and if the excavation didn't find the problem you're paying for the next one too.
So when I come out for sprinkler repair, I test the circuit before I touch the ground. I can tell from the controller end whether the signal is going out. I can tell at the valve whether the solenoid is responding. If both of those check out and the zone still won't run, then we're talking about the water side and I know roughly where to look.
That whole process usually takes less time than digging one hole. And more often than not it ends with a repair that's a wire splice or a solenoid swap rather than anything major.
I'd rather spend twenty minutes finding out than spend two hours in the wrong part of your yard.
One more thing about repair versus replace
Sometimes I get out to a system and the honest answer is that it's near the end. Original valves, brittle wire, heads that have been patched more than once. When that's the case I'll tell you, because I don't think it serves anybody for me to keep charging for repairs on something that's going to keep failing.
But that's less common than people expect. Most of the systems I look at are worth fixing, and the fix is smaller than the homeowner had braced for. A single zone going down is almost never a sign that the whole system is finished.
If your zone is out
If you're looking for sprinkler repair in Corinth, Lewisville, Flower Mound, or somewhere else in North Texas, tell me what it's doing, or not doing, and I'll come take a look at it. I'll find the actual cause and give you the number before any work starts.
Rob Dilts
Owner
RD Services
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