Signs of an irrigation leak in a Tucson yard
The most reliable sign is at the meter: it moves when the irrigation shutoff valve is open and stops when you close it. Around the yard, look for:
- A valve box full of water or mud when the system hasn't run.
- An emitter or sprinkler head that drips constantly at the lowest point of a zone. That means a valve isn't closing.
- One wet, dark patch in the gravel, or a spot where the rock has sunk.
- One plant flooded while others on the same line are dying. Water is escaping before it reaches the end of the run.
- Weak flow at the far emitters on a zone that used to work.
- White mineral crust or a mud stain on a wall, curb, or sidewalk next to a planting bed.
- Water running down the street gutter after a watering cycle.
- A water bill that climbs in summer by far more than the extra watering explains.
Irrigation mainline leak or zone leak: why it matters
An irrigation system has 2 kinds of pipe, and they leak in different ways.
The mainline runs from the backflow preventer to the valves. It's under full pressure day and night. A mainline leak never stops, shows on the meter at any hour, and costs the most.
The lateral lines run from each valve out to the emitters and heads. They hold water only while that zone is on. A lateral leak wastes water for the minutes the zone runs, and it mostly shows up as poor coverage and stressed plants.
A weeping valve sits between the two. Grit or mineral scale on the diaphragm keeps it from sealing, so water trickles into a zone around the clock. It looks like a slow lateral leak but bills like a mainline leak.
Why drip irrigation leaks stay hidden in Tucson yards
Most Tucson yards are rock or decomposed granite over bare soil, watered by buried drip tubing. There's no lawn to turn green over a leak, and dry desert soil takes in a great deal of water before anything shows on the surface. A split in a drip line under 3 inches of rock can run for an entire summer and the only evidence is the bill.
3 local conditions cause much of the damage we find:
- Sun and heat. Polyethylene drip tubing and exposed PVC turn brittle after years of Tucson sun. Tubing that has worked up to the surface cracks first.
- Wildlife. Rabbits, pack rats, ground squirrels, and javelina chew through drip tubing and emitters to get at the water, especially in the dry months before the monsoon.
- Winter freezes. Tucson averages around 12 nights a year at or below freezing. That's enough to crack an exposed backflow preventer, a vacuum breaker, or an above-ground PVC riser. The crack often goes unnoticed until the system is turned up in spring.
If you own a rock-landscaped yard, check the meter with the irrigation on and off at the start of each summer. It's a 10-minute check, and it catches the kind of leak that otherwise runs until fall.
How irrigation leak detection works
- Isolate irrigation from the house. We close the irrigation shutoff and read the meter, then open it and read again. This shows how much of the water loss belongs to the irrigation system.
- Test the mainline. With every zone off, a pressurized mainline should hold. If the meter moves, the leak is in the mainline, the backflow assembly, or a valve that's passing water.
- Find the valves. Valve boxes get buried under rock and roots. Valves and their control wires are traced with a locator from the timer.
- Run each zone. One zone at a time, we compare flow at the meter with what the emitters should be using and walk the line looking and listening for the loss.
- Pinpoint mainline breaks. A ground microphone is used along the mainline route. Small or deep leaks in plastic pipe can be confirmed with tracer gas.
- Mark everything found. Breaks, weeping valves, and damaged sections are flagged, with the zone number noted for each.
If the meter still moves with the irrigation shutoff closed, the leak isn't in the irrigation system. The next place to test is the underground water line between the meter and the house.
What affects the cost of irrigation leak detection
- Number of zones and the size of the lot.
- Whether the valves can be found. Buried or unknown valve locations add time.
- Mainline length and material. Irrigation mainlines are almost always plastic, which is harder to trace and quieter than metal.
- Ground cover. Deep rock, landscape fabric, pavers, and dense planting slow the search.
- Condition of the system. One clean break is a short job. A system with brittle tubing throughout may have many small leaks, and at that point we'll tell you that replacing a zone makes more sense than chasing each hole.
- A working shutoff and timer. We need to be able to turn zones on and off.
When an irrigation leak is urgent
Close the irrigation shutoff valve right away if a backflow preventer or mainline has broken open and is gushing, or if water is running toward the house, pooling against the foundation, or washing out soil beside a wall or walkway. The shutoff is usually a ball valve near the backflow assembly, often at the front of the house. Closing it leaves the house water on.
After that, the pressure is on the plants. In June, shrubs and young trees on drip can go from healthy to badly stressed within days without water. If the system has to stay off, hand water what matters most and get the leak located soon.
How to prepare for irrigation leak detection
- Find the timer and make sure it has power. Know which zone numbers water which areas, if you can.
- Locate the irrigation shutoff and any valve boxes you know of.
- Leave the system off the night before so the ground is dry and leaks are easier to see.
- Tell us about any recent digging, planting, or cable and utility work in the yard.
We locate irrigation leaks and don't repair them. Your landscaper or irrigation contractor does that part. After the repair, repeat the meter check with all zones off.
The meter should be still. Then run each zone and compare its flow with the others. Irrigation is one of several systems we test as part of leak detection for Tucson homes, and it's often the answer when the house itself checks out fine.
Irrigation leak questions homeowners ask
How do I know if my irrigation system is leaking?
Turn off everything in the house and make sure no irrigation zone is running. Read the meter.
Close the irrigation shutoff valve and read it again after 15 minutes. If the meter was moving before and stopped once the irrigation was shut off, the leak is in the irrigation mainline, the backflow assembly, or a valve.
Can you find a leak in buried drip tubing?
Yes. The zone is run while flow is watched at the meter, and the line is walked and listened to.
Larger losses usually show as wet soil under the rock once the zone has run for a while. The harder leaks are in the pressurized mainline, which is found by listening and, if needed, tracer gas.
What is a weeping valve?
A zone valve that doesn't close completely. Debris or mineral scale on the rubber diaphragm lets water pass into the zone all the time.
The sign is a low emitter or sprinkler head that drips for hours after the cycle ends. It's a small, steady loss that adds up on the bill.
Why did my backflow preventer start leaking after winter?
Water left in the brass body or the plastic parts expands when it freezes and cracks them. Tucson has enough freezing nights each year for this to be common on exposed assemblies. Insulating the backflow preventer before cold nights helps prevent it.
Could my high water bill be from irrigation even if the yard looks dry?
Yes. Dry soil and rock cover hide a lot of water. The meter test with the irrigation shutoff open and closed is the way to know.
Do you repair sprinklers or drip lines?
No. Leak Detective locates and marks irrigation leaks. Repairs are made by the landscaper or irrigation contractor you choose.