To find a sprinkler system leak, turn off the controller, read the meter, then run one zone at a time and watch for pooling, geysers, low pressure at heads and a meter that does not match the zone's expected flow. The zone that behaves wrongly holds the leak. If the leak turns out to be in the pressurized main or at the backflow device, hire a plumber. Sprinklers are one of several leak sources in our leaks and burst pipes section.
How do you know if your sprinkler system is leaking?
Signs include soggy ground that stays wet long after a cycle ends, a patch of lawn that is greener or sunken, water trickling toward the sidewalk, heads that spit weakly, a wet valve box, and a water bill that rises in the watering months. If the meter moves with the controller off, the leak is in the pressurized line.
Two different kinds of leak look alike but are not the same. Water that appears only while a zone runs points to the lateral lines, heads or valves downstream of that zone valve. Water that appears all the time, even with the system off, points to the main line that stays under pressure up to the valves, or to a valve that does not close.
A wet spot right at the valve box is common. So is a hissing or a chattering valve. A box full of water after a dry week is worth lifting the lid on.
The EPA says the average family wastes about 9,400 gallons a year to leaks inside and outside the home. An irrigation leak does not have to be dramatic to cost real money over a summer.
How can you test a sprinkler system zone by zone?
Do a meter test with the system off, then run each zone for a few minutes while you walk the area. First, with all water off in the house, read the meter. If it moves while the controller is off, the main line or a zone valve is leaking. If it holds, a leak only occurs when zones run.
Step by step:
- Turn the controller to off and make sure no other water is running.
- Read the meter and leak indicator, wait fifteen minutes, read again. Movement means a pressurized leak.
- Turn the controller to manual. Run zone 1 for three to five minutes.
- Walk the zone. Look for geysers, soft ground, heads that do not pop up or that mist heavily.
- Repeat for each zone, and note which one has flow at the meter that looks too high compared with the others.
- Check each valve box for standing water or a valve that weeps after the zone stops.
The EPA's Fix a Leak Week guidance also suggests checking irrigation systems each spring for damage and checking garden hose connections at the spigot. If your meter has a low-flow indicator, a spinning dial with the system off is the clearest sign. Our water meter leak detection page covers how to read one.
Where do sprinkler leaks usually hide?
Most leaks come from a short list: broken or cracked heads, worn seals at the base of a spray head, cracked risers hit by a mower or foot, a split in a poly lateral, loose fittings, valve diaphragms that no longer seal, and failed pipe in the mainline. Heads and risers are the most common and the easiest to fix.
Here is what each tells you:
- Geyser at a head. The riser or head is broken. A cheap part and a quick fix.
- Soggy ring around a head. A worn seal or a fitting at the base is leaking.
- Zone that never fully shuts off. A valve diaphragm or debris keeps it open.
- Low pressure across a zone. A broken lateral line upstream of the heads, or a leak lowering flow to every head.
- Wet ground between zones with the system off. A mainline leak. This is the one to leave to a plumber.
Roots, settling soil and old galvanized or thin-wall pipe can cause breaks in older Valley yards. Mixed-material systems, with plastic joined to metal, leak at the joints as the materials expand and contract in summer heat.
Does a sprinkler system need backflow testing?
Many water utilities require a backflow prevention assembly on an irrigation system and a periodic test of it, since irrigation water can contain fertilizer and soil. The rule differs by utility and device, so ask Burbank Water and Power, or your own water provider, what applies to your property before you assume.
A backflow device sits on the line that feeds the sprinklers. It stops water in the irrigation pipes from flowing back into the drinking water. A leaking assembly, one that spits water from a relief port, or one that has been frozen or damaged, needs repair or testing by a person qualified for it. Our page on backflow prevention testing explains what a test involves, and testing backflow covers the basics.
A sprinkler leak and a backflow problem can be mixed up. If water pours from the assembly every time a zone starts, the cause is the device or a pressure spike downstream, and it needs a plumber's eyes.
When should you call a plumber and not an irrigation company?
A plumber is who you want if the leak is in the pressurized main, where the line ties into your house supply, at the backflow assembly, or whenever the meter keeps running with the system off. Heads, nozzles and controller settings sit with an irrigation or landscape contractor. Many leaks cross both, so describe what you tested.
A local plumber we arrange will visit your property. Report which zone leaks, whether the meter runs with the controller off, and whether you struck a buried line. Put the details on the quote form, and the written price follows the visit.
Before any digging, call DigAlert at 811, which is free according to DigAlert. Valley yards often carry gas, electric and low-voltage lines near sprinkler lines.
Before anyone digs or replaces pipe, look up their license on the state contractors board website, and ask whether your city requires a permit.
How much does it cost to fix a sprinkler leak?
For a broken head or riser, the parts are inexpensive and the visit is often the main cost. A mainline repair costs more because of digging, pipe and restoring the lawn or paving. We have no verified Burbank price list for irrigation work, so request a written quote with parts, labor and any permit itemized.
The main things that raise the cost: line depth and length, hardscape over the pipe, hard soil, the count of leaks, and whether the system needs a new valve or backflow assembly. If the system is old and brittle, the plumber may suggest replacing a zone line rather than patching it again.
Also ask about water-wise changes at the same visit. Burbank Water and Power lists rebates and tips on low-water landscaping on its website, and a repair visit is a cheap time to fix a spray head that overspray has been wasting.
Questions people ask
How long does sprinkler system leak detection take?
A zone-by-zone test of an ordinary yard takes an hour or two. Tracing a mainline leak with locating gear can take longer, and repairs may be a separate visit. Ask how many zones the system has, and whether the price covers both the meter test and the zone test.
What should I ask before I hire someone for sprinkler system leak detection?
Ask whether they test the main line as well as the zones, who repairs heads and who repairs the pipe, and whether they will call 811 before digging. Ask what is included if they cannot find the leak. Get a contractor license number and check it against the state's records.
Do I need to be home for sprinkler system leak detection?
Be home at the start to open gates, show the controller and valve boxes, and confirm which zones you have seen trouble in. Bring the controller schedule too. Staying for the entire test is optional, but have the plumber phone you before any digging or part replacement.
How much water can a broken sprinkler head waste?
More than most people expect. A head with a broken riser can run the full length of every cycle, several times a week. Your own meter is the best measure, since it shows the actual flow while that zone runs. Compare the reading across zones to see which one is off.
Can I use a sealant on a leaking sprinkler pipe?
For a pressurized fitting, a sealant is rarely a lasting fix. Replace the fitting, or cut out the damaged pipe and couple in new. Our page on water pipe leak sealant explains what sealants can and cannot do on potable lines, and most of that carries over to irrigation.
This guide is one of many on Lankershim Plumbing.
References
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