Home / Guides / Underground vs irrigation leak

Guide

Underground leak vs irrigation leak

A wet patch in the yard, a sinking spot near the driveway, or a meter that won’t stop can come from the buried water line that feeds the house, or the irrigation system that waters the landscape. Telling them apart early decides who you call and whether anyone needs to dig.

How can you distinguish a buried water-line leak from irrigation?

Turn off the irrigation system at its controller and its own shutoff valve, if it has one

Turn off all water use indoors

Watch the meter—if it stops, the leak is likely on the irrigation side; if it keeps moving, the loss is likely on a supply line or elsewhere in the house

Then look at where the wet spot is and when it appears. Irrigation leaks usually follow zones and watering times. Supply-line leaks usually stay wet all the time.

How do the two water systems differ?

	Main supply line	Irrigation system
Pressure	Always pressurized while the supply is on	Laterals pressurized only when a zone runs; mainline may stay pressurized up to the valves
Where it runs	Between the meter (or well) and the house	From a tie-in point to valve boxes, then out to zones
When water shows	Constantly, day and night	Often only during or after watering cycles
Typical wet spot	Along the path from meter to house	Near heads, drip emitters, valve boxes or along lateral runs
Who usually repairs	A plumbing contractor	An irrigation or landscape contractor, sometimes a plumber

What clues point toward an irrigation leak?

The wet spot sits near a sprinkler head, drip line or valve box

It is wetter after watering and dries between cycles

One zone runs weak, sprays oddly or won’t shut off

Water collects in a valve box

The meter stops when the irrigation shutoff is closed

The problem started after landscaping work or a controller reset

What clues point toward a buried supply-line leak?

The wet spot is on or near the route between the meter and the house

It stays wet regardless of watering schedule

The meter keeps moving with irrigation and the house turned off at their own valves

There is a sinking or softened area along that route

Water pressure in the house has dropped

You can hear water near the meter box with everything off

See underground water line leak detection.

Other sources of yard water

Storm runoff—summer monsoon rain can pool in low spots and stay damp under gravel for days

Drain or sewer lines—wet ground that smells, or appears when fixtures drain

Evaporative cooler drain lines—a steady trickle from the roof or a side yard

Pool or spa overflow and backwash

A neighbor’s irrigation or runoff crossing the property line

A hose bib or outdoor tap dripping into the ground

See plumbing leaks versus sewer, roof or monsoon moisture.

Safe checks you can do

Run each zone separately and walk the yard while it runs. Look for geysers, pooling, weak heads or a wet valve box.

Turn the controller off for a day or two. Does the wet spot dry?

Close your own irrigation shutoff or backflow valve (not a utility valve) if your system has one and it turns easily. Do not touch the backflow test cocks. Then watch the meter.

Close the house shutoff (on your side of the meter) and watch the meter again.

Mark the wet spot’s edge and check it the next day.

Photograph what you see, including the meter reading before and after.

Never force a stiff valve or turn utility-side valves at the meter.

How should you interpret the signs?

Irrigation off	House shutoff closed	Meter	Likely branch
Yes	No	Stops	Irrigation system
Yes	No	Still moving	House plumbing, supply line or an unknown branch
Yes	Yes	Stops	Inside the home or after the house shutoff
Yes	Yes	Still moving	Between the meter and the house shutoff, or an un-isolated branch
No (zone running)	—	Wet spot appears or grows	Irrigation—check that zone

These results narrow the branch. They do not give the exact location.

Why should you avoid digging for an unconfirmed leak?

Digging around a suspected leak can damage gas, electric, telecom or water lines—and it often misses the leak. Contact Arizona 811 before any digging; allow at least two full working days for marking.

Multi-unit excavation exception: for excavations at apartment communities or mobile-home parks, A.R.S. § 40-360.22 adds a certified-mail inquiry to the landlord, who may take up to ten working days to respond with marking. 811 marks utility-owned lines; private lines may need a private locator. 811 does not find leaks.

Street or property?

If water is coming up in the street, sidewalk or right at the meter box, contact your water provider first. Where the provider’s responsibility ends depends on the provider and property. See Kingman water main versus private water line for how to route the call.

Who should you contact for each possible source?

Situation	Usually start with
Water surfacing in the street or at the meter box	Your water provider
Leak confirmed on irrigation, zone or valve	An irrigation-capable contractor
Meter moving with irrigation off, no obvious spot	A leak investigation for the buried supply line
Wet spot that smells or appears with drain use	A drain or sewer professional
Storm-related pooling only	Watch it dry; no leak investigation needed if the meter is still

Frequently asked questions

My yard has a wet spot but my meter isn’t moving. Is it a leak?

Probably not a supply leak. Check whether it follows watering times, rain or drain use.

Can an irrigation leak raise my water bill?

Yes. Irrigation leaks can run unnoticed, especially on drip systems or zones that water at night.

Does gravel or rock landscaping hide leaks?

It can. Water may spread under gravel or decomposed granite before showing. Look for darker patches or plant growth in odd spots.

Should I turn off my irrigation if I suspect a leak?

Yes, turning off the controller and, if present, the irrigation shutoff is a safe first step.

Who fixes a buried supply line versus irrigation?

Supply lines and irrigation may fall under different work classifications. Check what is included in a proposed repair and whether permits or licensing requirements apply.

Can a monsoon cause a leak?

Storm water itself is not a pipe leak, though it can make wet spots harder to read. Use the meter check to tell the difference.

Want a second opinion?

If you’ve run these checks and still aren’t sure which system is leaking, call Kingman Leakcrest at (928) 437-2800.

Call (928) 437-2800