Sprinkler problems always show up when you need the system most. Hot dry July. You turn on the sprinklers and something is wrong. A head does not pop up. A zone does not turn on. Water sprays onto the sidewalk instead of the grass. Here is how to diagnose and fix the most common sprinkler problems yourself.
Problem 1: Sprinkler Head Does Not Pop Up
You turn on the zone and one head stays down. The rest work fine.
Likely cause: The head is clogged with dirt or debris. Fix: Turn off the zone. Pull up the stuck head by hand. Clean around the stem with a cloth. Remove the nozzle and check for debris. Flush with clean water. If the head is physically damaged or the spring is broken, replace the entire head.
Other cause: The head is installed too deep and grass has grown over it. Fix: Dig up the head. Add a riser to raise it to the correct height. The top of the head should be flush with the soil.
Problem 2: Zone Does Not Turn On At All
You activate a zone from the controller. Nothing happens. No water. No sound.
Likely cause: Wiring problem. Fix: Check the controller first. Is the correct zone number programmed? Is there a run time set for that zone? Check the wire connections at the controller. Tighten any loose terminal screws. Check the wire connections at the valve solenoid. Waterproof wire connectors can fail. Cut them off and install new ones. Check for cut wires. The most common location for cut wires is where the wire exits the house or crosses garden beds where shoveling happens.
Other cause: Bad solenoid. Fix: The solenoid is the cylinder on top of the valve with two wires. Unscrew it. Screw on a new one. Reconnect the wires. If the zone now works, the solenoid was bad.
Problem 3: Low Water Pressure or Weak Spray
The sprinklers run but the spray is weak. Heads barely pop up. Coverage is terrible.
Likely cause: Too many heads on one zone exceeding your flow rate. Fix: Check your design. Each zone should not exceed your available GPM. Remove one head or split the zone into two. Likely cause: Main shut-off valve is not fully open. Fix: Locate the shut-off valve. Turn it counterclockwise until it stops. Likely cause: Leak in the main line. Fix: Look for wet spots in the yard where the main line runs. A constantly wet area with no heads nearby indicates an underground leak. Dig up the leak. Cut out the damaged section of pipe. Splice in a new section with couplings.
Problem 4: Sprinkler Head Leaking or Water Pooling Around Head
When the zone shuts off, water continues to seep out around one or more heads. Low spots in the yard have standing water.
Likely cause: Low-head drainage. Water in the pipes drains out of the lowest head after the zone shuts off. Fix: Install heads with built-in check valves like the Hunter PGP-Ultra or Rain Bird SAM series. The check valve holds water in the pipe instead of letting it drain out. Alternatively, install a separate check valve below the head.
Other cause: Worn wiper seal. Fix: The wiper seal is the rubber ring around the pop-up stem. Over time it wears out and leaks. Replace the entire head or rebuild it with a new seal kit.
Problem 5: Spray Pattern Is Wrong or Uneven
The sprinkler waters the sidewalk more than the grass. Or there are dry spots in the middle of the zone.
Likely cause: Head is out of adjustment. Fix: Adjust the arc and radius on the problem head. Use the adjustment tool or a flathead screwdriver. Adjust while the zone is running so you can see the changes. Likely cause: Nozzle is clogged. Fix: Unscrew the nozzle. Clean it with the included cleaning needle or a small wire. Flush the head before reinstalling the nozzle. Likely cause: Head is tilted. Fix: The head should be vertical. If it is tilted, dig around it. Adjust the swing joint to make it straight. Pack dirt back around it.
Problem 6: Valve Will Not Shut Off
A zone runs continuously even after the controller shuts it off. You have to turn off the main water to stop it.
Likely cause: Debris stuck in the valve. Fix: Turn off the main water. Unscrew the valve bonnet. Remove the diaphragm. Clean the valve body and diaphragm with clean water. Check for a tiny rock or piece of debris holding the valve open. Reassemble. Likely cause: Valve diaphragm is torn. Fix: Replace the diaphragm. Valve rebuild kits include a new diaphragm, spring, and O-rings. Unscrew the bonnet. Replace the old parts with new ones. Reassemble.
Problem 7: Controller Display Is Blank
The controller screen shows nothing. The system does not run.
Likely cause: No power. Fix: Check that the controller is plugged in. Check the outlet with another device. Check the circuit breaker. Many controllers are on GFCI outlets that can trip. Press the reset button on the outlet. Likely cause: Blown fuse. Fix: Open the controller cabinet. Look for a small glass fuse. Remove and inspect. If the wire inside is broken, replace with the same amperage fuse.
Problem 8: Backflow Preventer Leaking
Water drips or sprays from the backflow preventer.
Likely cause: Freeze damage. If the backflow was not properly winterized, internal parts can crack. Fix: This is a job for a licensed plumber in many areas. Backflow preventers protect drinking water. Repairs often require testing and certification after the fix. Do not attempt this repair unless you are confident.
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