Irrigation Repair Guide: Fixing Sprinkler Heads, Valves, Broken Pipes, and Controllers
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A lawn irrigation system has a few hundred feet of buried pipe, a dozen or more sprinkler heads, several electric valves, and a controller that orchestrates the whole thing. When something breaks — a head gets hit by a mower, a pipe cracks from freezing, a valve sticks open, or a zone stops working — the fix is usually straightforward if you understand how the system works. Most irrigation repairs take 30 minutes and cost under $20 in parts. This guide covers the common failures and how to fix them.
Sprinkler Head Replacement
Pop-up sprinkler heads are the most commonly damaged component. Mower blades crack the caps, foot traffic breaks the risers, and age causes the seals to fail (resulting in a head that runs constantly or never fully pops up). Replacement heads cost $3 to $15 and install in minutes.
To replace a head: dig around the head to expose the riser fitting. Unscrew the head from the riser (it threads on). Screw on the new head. Run the zone to verify spray pattern and coverage. Adjust the arc and radius on the new head to match the area it covers — most pop-up heads have adjustment screws for both.
Match the new head to the old one. Spray heads and rotor heads are different products — spray heads cover small areas with a fixed fan pattern, while rotor heads cover large areas with a rotating stream. Using the wrong type creates either flooding or dry spots. Note the brand, model, and nozzle size of the old head before shopping.
Broken risers (the threaded fitting that connects the head to the lateral pipe) are a common collateral damage when a head breaks. If the riser is cracked or the threads are stripped, replace the riser too. A swing joint assembly (a flexible riser using multiple funny-pipe fittings) allows the head to flex on impact instead of breaking — a worthwhile upgrade from a rigid riser.
Valve Diagnosis and Repair
Each zone in your irrigation system has an electric valve that opens when the controller sends power and closes when the power stops. A valve that will not open, will not close, or leaks externally is a common problem. The fix is usually a diaphragm replacement ($5 to $15) rather than full valve replacement.
A zone that will not turn on: check the controller first (is the zone programmed? is there power?). Then check the wire connection at the valve (corrosion and broken wires are common). If power is reaching the valve solenoid, the solenoid may be dead — test it with a multimeter or swap it with a known-good solenoid from another valve. If the solenoid clicks but water does not flow, the diaphragm is stuck closed.
A zone that will not turn off: the valve diaphragm is stuck open or torn. Manual override left on is the first thing to check — turn the solenoid clockwise until snug (some valves also have a bleed screw that must be closed). If the valve still runs, the diaphragm needs replacement. Turn off the water supply, disassemble the valve top, replace the diaphragm, and reassemble.
A valve leaking from the bonnet (the join between the valve top and body) usually means the diaphragm or the bonnet seal is worn. Disassemble, inspect, clean the seating surfaces, and replace the diaphragm. Reassemble with even torque on the bonnet screws — uneven tightening warps the bonnet and causes continued leaking.
Fixing Broken Pipes
Lateral pipe breaks are usually caused by freezing (improper winterization), tree roots, or accidental digging. The repair is a slip-fix coupling — a telescoping fitting that slides over the pipe, spans the break, and glues in place with PVC primer and cement. Cut out the damaged section, clean the pipe ends, and install the coupling.
For PVC irrigation pipe (the most common type), use PVC primer (purple) and PVC cement (clear or blue) for all joints. Apply primer to both surfaces, then cement to both surfaces, and push the fitting onto the pipe with a quarter-turn twist. Hold for 30 seconds. Let the joint cure for the time specified on the cement can (usually 15 minutes to 2 hours depending on pipe size and temperature) before pressurizing.
Funny pipe (flexible polyethylene tubing used for sprinkler head connections) repairs with barbed fittings and clamps. Cut out the damaged section, push barbed couplings into each cut end, and secure with stainless steel clamps. This flexible pipe handles the last few feet from the lateral to each sprinkler head.
When digging to access a broken pipe, dig carefully. Other utility lines (gas, electric, cable, sewer) may run nearby. Call 811 before you dig to have utility lines marked. Within the irrigation system, other lateral pipes and valve wiring may run close to the break — a careless shovel strike can turn a single-pipe repair into a multi-pipe disaster.
Controller Troubleshooting and Winterization
If no zones run: check power to the controller (is the outlet live? is the transformer producing 24V AC?). Check the common wire (the white wire that completes the circuit for all valves). A broken common wire kills all zones simultaneously. Test by connecting the common wire directly to a valve terminal — if one zone then works, the common wire is intact.
If one zone does not run but others do: the problem is the zone wire, the solenoid, or the valve. Test the wire by measuring resistance from the controller terminal to the valve solenoid — it should read 20 to 60 ohms. Infinite resistance means a broken wire. Zero ohms means a short. Resistance within range but no operation means the solenoid or valve is the problem.
Modern smart controllers (Rachio, Hunter Hydrawise, Rain Bird ESP-TM2) connect to WiFi and adjust watering based on weather data. If a smart controller stops responding, check your WiFi network first, then power-cycle the controller. Most smart controllers have a manual override mode that runs zones independent of WiFi connectivity.
Winterization prevents freeze damage. In climates where ground freezes, blow out the system with compressed air before the first hard freeze. An air compressor delivers 50 to 80 PSI through the system, pushing water out of all pipes and heads. Run each zone for 2 to 3 minutes until only air comes from the heads. Do not exceed 80 PSI — higher pressure damages pipes, fittings, and heads.
Frequently Asked Questions
Why is one zone not spraying as far as it used to?
Most likely low water pressure in that zone. Check for a partially closed valve (manual gate valve or the zone valve itself). Check for a broken pipe or head in the zone that is leaking water before it reaches the other heads — one broken head can rob pressure from the entire zone. Also check the nozzle on the underperforming heads for clogs — dirt and debris in the nozzle restrict the spray.
Can I add a sprinkler head to an existing zone?
Yes, but adding heads reduces the pressure available to each existing head on that zone. If the zone already has marginal coverage, adding another head makes all of them underperform. Calculate the total GPM (gallons per minute) of all heads on the zone and compare it to the system's available GPM. If adding the new head pushes the total past the available GPM, the zone needs to be split into two zones with a new valve.
How do I winterize my irrigation system?
Blow out each zone with compressed air at 50 to 80 PSI (never exceed 80 PSI) until only air exits the heads — typically 2 to 3 minutes per zone. Shut off the main irrigation water supply. Drain any water from the backflow preventer. Open manual drain valves if the system has them. Set the controller to rain mode or off. In spring, reverse the process: close drains, open supply, run each zone briefly, and check for leaks.