Wet spots that never dry, water bubbling from the lawn, a soggy valve box or water running down the sidewalk can all mean a sprinkler leak.
Sprinkler leaks can come from heads, fittings, valves, lateral pipes, the mainline or the backflow preventer. When the leak happens tells you a lot about where it is.
Diagnose My Sprinkler Problem See Typical Repair Cost Find a Sprinkler Pro
Quick Answer
Most sprinkler leaks come from a cracked head or fitting, a broken lateral pipe, a leaking valve, or a mainline or backflow problem. The first thing to determine is whether the leak happens only while the sprinklers run, or even when they’re off. Leaks that continue with the system off are usually more serious because that part of the system is always under pressure.
What You May Be Seeing
- Soggy or spongy areas in the lawn
- Water bubbling up from the ground
- A valve box full of water
- Water seeping around a sprinkler head
- Water running onto the sidewalk or driveway
- Water around the backflow preventer
- Low pressure in one zone
- A higher water bill
Leaks on the zone side of a valve only flow while that zone runs. Leaks on the mainline, at the valves or at the backflow preventer can flow all the time because those parts stay pressurized.
The First Question to Ask
Does the leak happen only while the sprinklers run, or even when they’re off?
A leak that appears only during watering is usually on a zone’s lateral pipe, head or fitting. A leak that continues with the system off points to the mainline, a valve that isn’t sealing, or the backflow preventer.
If the Leak Happens Only While the Sprinklers Run
The leak is probably downstream of a zone valve.
Common causes include:
- Cracked head: damage from mowers, traffic or age
- Broken fitting or swing pipe: under or near a head
- Damaged riser: the short pipe feeding the head
- Broken lateral pipe: the pipe carrying water through the zone
If the Leak Continues When the System Is Off
Pressurized parts are more likely involved.
Common causes include:
- Mainline leak: the always-pressurized supply pipe
- Valve not sealing: water seeps through or around a valve
- Backflow preventer leak: a failed part or freeze damage
- Pressurized fitting failure: a cracked fitting on the supply side
The Valve Box Is Full of Water
Standing water in a valve box can come from a leaking valve, a solenoid or fitting leak, or a pipe leak nearby. Rain and groundwater can also collect there, so note whether it refills after being emptied.
Water Is Bubbling Up From the Lawn
Bubbling or a constantly wet patch usually means a broken pipe or fitting underground. Roots, freezes and digging are common causes.
After a Freeze
Freezing can crack pipes, fittings and backflow preventers. Leaks that appear when the system is turned on after cold weather are often freeze damage.
What You Can Check Yourself
- Note whether the leak happens only during watering or all the time
- Run one zone at a time and watch where water appears
- Look for wet areas, bubbling or sunken soil
- Check whether the leak stops when the irrigation shutoff is closed
- Look (without touching parts) at the backflow preventer for spraying or dripping
- If water is spraying or flooding, close the irrigation shutoff
What a Technician May Test
- Zone isolation and run tests
- Leak location and careful excavation
- Pressure tests
- Water meter observation
- Valve and backflow inspection
Most Common Causes
- Cracked sprinkler head
- Broken fitting or swing joint
- Broken lateral pipe
- Leaking valve or solenoid
- Mainline leak
- Backflow preventer leak
- Root, freeze or digging damage
Repair or Replace?
Most sprinkler leaks are repaired by replacing the damaged head, fitting, pipe section or valve part. Widespread brittle pipe, repeated leaks or an aging system may be worth a broader inspection before deciding on larger work.
When to Call a Sprinkler Professional
Call a professional if:
- The leak continues with the system off
- Water is spraying from the backflow preventer
- Water is near the foundation
- You can’t find the source
- Closing the irrigation shutoff doesn’t stop it
Find a sprinkler repair pro or read our emergency shutoff guide if water won’t stop.
Related Sprinkler Problems
- How Do I Know If I Have an Underground Sprinkler Leak?
- Why Is My Sprinkler Valve Leaking?
- Why Is My Sprinkler Valve Box Full of Water?
- Why Is My Backflow Preventer Leaking?
- Why Is My Sprinkler Pipe Leaking?
- Can My Sprinkler System Cause a High Water Bill?
Related Repairs
Typical Repair Cost
What you pay depends on the cause, the parts and your area. See our Sprinkler Leak Repair Cost Guide for typical ranges. Prices vary, and only an on-site diagnosis can give you an actual quote.
Frequently Asked Questions
How do I find a sprinkler leak?
Run one zone at a time and watch for water where it shouldn’t be. Note whether the leak continues with the system off; that tells you whether it’s on a zone or the pressurized supply side.
Why does my sprinkler leak when it’s off?
The mainline, valves and backflow preventer stay pressurized, so a leak in any of them can flow even when no zone is running.
Can a sprinkler leak raise my water bill?
Yes. A continuous leak on the pressurized side of the system can use a lot of water over time.
Is a leaking sprinkler valve serious?
It depends. A small seep may be minor, but a valve that won’t seal can waste water continuously and should be repaired.
Should I turn off my sprinkler system if it’s leaking?
If the leak continues with the system off or is causing damage, close the irrigation shutoff until it’s repaired.
Bottom Line
Sprinkler leaks are usually caused by damaged heads, fittings, pipes, valves or the backflow preventer. Knowing whether the leak happens only during watering or all the time is the fastest way to narrow it down.
A technician can isolate the zone or line, locate the leak and repair just the damaged section.
Diagnose My Sprinkler Problem See Typical Repair Cost Find a Sprinkler Pro
