A systematic approach is required to restore efficiency when a home sprinkler system’s performance declines. Before inspecting buried components or electrical parts, safety is the first consideration. Always shut off the main water supply and disconnect the power to the controller to prevent accidental activation or electric shock. Troubleshooting aims to isolate the failure, moving methodically from the power source to the terminal components. This guide addresses the most frequent issues affecting residential sprinkler operation.
When the System Fails to Start
When the entire sprinkler system fails to activate for a scheduled cycle, the problem is usually related to power or programming. The initial step involves verifying the power supply to the irrigation controller, often a low-voltage transformer. Check the circuit breaker for the outlet to ensure it has not tripped, preventing the controller from receiving input power.
If the controller display is blank or non-responsive, confirm the programming clock is set correctly. Ensure the system is not inadvertently set to “System Off” or “Rain Delay” status, as these settings override scheduled watering cycles. A functioning controller that still fails to initiate watering may be blocked by an active rain sensor.
A rain sensor interrupts the common wire circuit when it detects moisture, preventing the valves from opening. To test if the sensor is the cause, locate the bypass switch on the controller and temporarily disable the sensor’s function. If the system activates when bypassed, the sensor may be faulty or still drying out. Finally, ensure the main manual shut-off valve, which supplies water to the system, is fully open.
Resolving Poor Coverage and Low Water Pressure
A system that activates but delivers inadequate water suffers from a hydraulic performance issue, manifesting as poor coverage or low pressure at the sprinkler heads. Begin by examining the individual sprinkler heads, as restricted flow is often caused by debris lodged in the nozzle or filter screen. Pop-up heads contain small internal screens that clog with sediment, requiring removal and cleaning to restore the intended flow rate.
If low pressure is isolated to a single zone, the problem is localized to that lateral line or its control valve. If the issue is system-wide, a restriction in the main line or a faulty backflow device may be the cause. Undetected leaks in the lateral lines downstream of the zone valve also reduce pressure. Water escaping from a puncture diverts volume away from the heads, reducing spray distance.
To confirm a lateral line leak, observe the ground while the zone is running for signs of pooling water or unusually lush turf. Some control valves have an external flow control screw that regulates the maximum water permitted through the valve. While this screw can optimize flow, turning it too far restricts the water supply, mimicking low pressure. Adjusting this screw must be done cautiously, as over-tightening can damage the valve diaphragm.
Identifying and Repairing Constant Leaks
Continuous water flow or seepage when the system is off indicates a zone valve failure, allowing water to escape past the sealing mechanism. A valve that refuses to close is typically due to debris, such as sand or small stones, preventing the rubber diaphragm from seating properly. This obstruction allows water pressure to leak through the valve, constantly supplying the downstream zone.
The valve’s solenoid, the electromagnetic component that opens the valve, can also malfunction from an electrical short or a stuck internal plunger. If the plunger fails to reseat, it holds the valve partially open by allowing water pressure to act upon the diaphragm. Repairing a constantly leaking valve involves turning off the main water supply, disassembling the valve’s bonnet, flushing debris, and inspecting the diaphragm for damage.
Catastrophic gushing leaks, presenting as geysers, usually result from a mainline or lateral line broken by digging, freeze damage, or vehicle traffic. The immediate action is to shut off the system’s main water supply valve to prevent extensive water loss. A physically broken sprinkler head causes a significant leak and requires full replacement. A final leak type is low-head drainage, where water weeps out of the lowest head after the cycle finishes due to gravity. This issue is resolved by installing check valves beneath the lowest sprinkler heads, which hold water in the line when system pressure drops.