The detection of leaks in an irrigation system is a necessary practice for both environmental stewardship and property management. A seemingly small leak can waste thousands of gallons of water over a season, directly translating to higher utility costs. Since much of the system, including the main supply lines and control valves, is buried underground, leaks often remain hidden until they cause noticeable damage or excessive water use. Proactive inspection is the most effective way to ensure system longevity and prevent the financial and environmental consequences of water loss.
Identifying the Signs of a Leak
The first indication of a leak often appears not on the lawn itself, but on the monthly water bill. An unexplained, significant spike in consumption is a strong signal that water is escaping the system somewhere on the property. Even without a bill spike, visual cues in the landscape can alert a property owner to a problem.
A localized area of soggy turf or overly lush grass, particularly when the irrigation system has not been running, suggests a consistent underground water source. This excessive saturation can lead to mold or mildew growth. Visible pooling or runoff near sidewalks or pavement, especially outside of scheduled watering times, is another sign of a leak.
A less obvious sign is the presence of brown, dry patches in the lawn, which can be an indirect result of a large leak elsewhere in the zone. The pressure drop caused by the leak may prevent water from reaching the farthest or highest sprinkler heads, leading to inadequate coverage. Finally, if you hear a faint hissing, bubbling, or constant running water sound coming from an area of the yard, this can indicate a pressurized leak in a buried pipe, even when the system is off.
Confirming the Leak with a Water Meter
Before investigating the system itself, the property’s main water meter can provide confirmation that a leak exists. Begin by ensuring all water-using appliances indoors and outdoors are completely shut off, including toilets, faucets, and the irrigation controller. This step isolates the water meter from all intentional water use.
Next, locate the water meter, which is typically housed in a buried box near the street or sidewalk. Inside the meter face, look for the low-flow indicator, a small component that is sensitive to water movement, often appearing as a small triangle, wheel, or asterisk. If this indicator is spinning or moving when no water is being used, it confirms a continuous leak is present.
If your meter lacks a low-flow indicator, record the meter’s main numerical reading. After ensuring no water is used for 15 to 30 minutes, check the reading again. Any increase in the digits confirms that water is flowing through the meter and escaping the system somewhere on the property.
Pinpointing Main Line and Valve Leaks
Once a leak is confirmed, the next step is to isolate the problem to the main line or the control valves. The main line is always pressurized, even when the irrigation controller is off, meaning a leak here is constant and often the most wasteful. To isolate the main line, shut off the water supply to the entire irrigation system, usually by closing a ball valve located near the backflow prevention device.
If the water meter’s low-flow indicator stops moving after the irrigation isolation valve is closed, the leak is within the irrigation system itself. If the indicator continues to move, the leak is in the service line between the meter and the irrigation shut-off valve. Visual checks for main line leaks involve looking for consistently saturated soil or sinking ground along the path the main pipe is expected to take.
Valve leaks, often called weeping valves, occur when the internal diaphragm seal fails to close completely, allowing water to slowly seep into a zone. To check for this, visually inspect the valve manifold box for standing water, which suggests a constant drip from the valve body or its fittings. You can also manually activate a zone at the valve box and listen closely for a hissing or bubbling sound after the zone is shut off, indicating water is still passing through the valve.
Checking Sprinkler Heads and Drip Emitters
The final stage of inspection involves component-level leaks that occur downstream from the zone valves. These leaks are usually only evident when the system is running or immediately after it shuts off. To check sprinkler heads, manually run each zone one at a time and walk the area for visual inspection.
Look for heads that are broken, cracked, or spraying an abnormal pattern, as physical damage is a common cause of water waste. Inspect the base of the sprinkler head riser for water bubbling up, which suggests a leak in the connection between the head and the lateral line. A common issue is low-head drainage, where water slowly trickles out of the lowest heads in a zone after the system has turned off, indicating a weeping valve or a lack of check valves in the heads.
For drip irrigation systems, the process is similar, requiring you to run the drip zone and walk the line to look for visible water loss. Check the main drip tubing for severed sections, punctures, or holes, which can be caused by gardening tools or rodents. Missing or damaged emitters will cause a noticeable stream or geyser of water rather than a slow drip.