Sprinkler System Troubleshooting Guide

Low Water Pressure

Symptoms: Heads barely pop up, spray distance is short, rotors barely rotate or don't reach full distance, poor coverage on zones that previously worked fine.

Possible causes and fixes:

• Main valve not fully open: Check that the irrigation shut-off valve is turned completely open. After winterization, it's common to forget to fully reopen it.
• Backflow preventer partially closed: Both handles on the backflow preventer must be fully open (parallel to the pipe). A 45-degree handle reduces flow dramatically.
• City water pressure dropped: Test static pressure with a gauge at an outdoor hose bib. If pressure is below 40 PSI, contact your water provider.
• Pipe leak: A leak anywhere in the system reduces pressure for all downstream heads. Look for unexpectedly soggy or green areas. See the pipe leaks section below.
• Too many heads on one zone: If heads were added to an existing zone, the total GPM demand may exceed supply. The zone may need to be split. See our zone planning guide.
• Clogged filter: Some systems have an inline filter after the backflow preventer. Sediment buildup restricts flow. Clean or replace the filter screen.

Broken or Stuck Sprinkler Heads

Symptoms: Head doesn't pop up, water gushes from a head location, head pops up but doesn't spray properly, rotor doesn't rotate.

• Head won't pop up: Dirt or debris in the riser mechanism. Pull the head up manually with the zone running. If it moves freely, debris may have washed out. If stuck, replace the head ($5–$25).
• Water geyser at head location: The head body is cracked or broken, usually from being hit by a mower or vehicle. Unscrew the head, take it to a hardware store, and buy a matching replacement. Screw the new head onto the existing riser.
• Head sprays sideways or in wrong direction: The head has rotated in its socket. Turn the zone on, grip the head body (not the nozzle), and twist it to the correct orientation.
• Rotor won't rotate: Internal gear mechanism is worn or debris is jamming it. Replace the rotor internals or the entire head. This is a common post-winter issue — debris from fall enters the mechanism.
• Nozzle sprays unevenly or mists: Clogged nozzle. Unscrew the nozzle, remove and rinse the filter screen underneath, and clear any debris from the nozzle openings with a pin or thin wire.

Leaking Valves

Symptoms: Water seeping from valve box, zone continues to run after controller shuts it off, low constant flow from heads when the system is off.

• Zone won't shut off: The valve diaphragm is likely torn or has debris stuck under it. Turn off the water, open the valve bonnet (top cap), remove the diaphragm and spring, clean everything thoroughly, and reassemble. If the diaphragm is torn, replace it ($10–$20 rebuild kit).
• Seeping from valve body: The solenoid (electric actuator) may be loose. Tighten it by hand — do not use pliers. If seeping continues, the solenoid O-ring may need replacement.
• Multiple valves leaking: Could indicate excessive system pressure. Check static pressure — if above 80 PSI, install a pressure regulator to protect your entire system.

Controller Issues

Symptoms: System doesn't turn on at scheduled time, display is blank, zones skip or run out of order, manual start works but auto doesn't.

• Blank display: Check that the controller has power. Look for a tripped breaker or blown fuse. Check the backup battery — if it's dead and power was interrupted, the schedule may be lost.
• Schedule doesn't run: Verify the controller isn't in "off" or "rain delay" mode. Check that the current time/date is correct. If a rain sensor is connected, check if it's stuck in the "wet" position.
• Smart controller not connecting: Reset the WiFi connection. Check your router. If you changed your WiFi password since winterization, the controller needs the new credentials. See our smart controller guide for model-specific troubleshooting.
• One zone doesn't activate: Test the zone manually at the controller. If it works manually but not on schedule, the programming for that zone is likely off. If it doesn't work manually either, the valve wire may be damaged. Check wire connections at both the controller and valve.

Zone Not Turning On

Symptoms: Controller says the zone is running, but no water comes from any heads in that zone.

• Check the valve manually: Open the valve box and manually turn the solenoid (rotate it 1/4 turn counterclockwise). If water flows, the issue is electrical — the solenoid isn't receiving signal.
• Cut or damaged wire: The most common cause in Idaho — especially after winter. Gophers, frost heave, or digging can damage the low-voltage wire between the controller and valve. Trace the wire and look for breaks or damage.
• Bad solenoid: If the valve doesn't open manually via the solenoid, the solenoid may be dead. Replace it ($15–$30) — they simply screw on and connect with wire nuts.
• Valve stuck closed: Debris in the valve body can prevent the diaphragm from opening. Disassemble, clean, and reassemble the valve.

Uneven Coverage

Symptoms: Some areas of the lawn are brown/dry while others are green and lush, even within the same zone.

• Heads out of alignment: Heads that have shifted or tilted spray water in the wrong direction. Run the zone and walk the entire area, checking each head's spray pattern. Straighten and adjust as needed.
• Obstructed heads: Grass, mulch, or soil has grown over the head and blocks the spray. Clear a 2–3 inch radius around each head. You may need to raise heads that have sunk — trim riser extensions are available at hardware stores.
• Mixed head types on one zone: If sprays and rotors are on the same zone, the spray areas get 3x more water. They must be separated onto different zones. See zone planning.
• Pressure variation: Heads closer to the valve get more pressure than distant heads. Install pressure-regulating spray bodies or check valves to equalize performance.
• Sun/shade differences: What looks like a coverage problem may actually be a scheduling problem. South-facing areas need more water than north-facing areas.

Pipe Leaks and Repair

Symptoms: Soggy area in the yard that shouldn't be wet, water bubbling up when a zone runs, unusually high water bill, reduced pressure on one or more zones.

• Locating the leak: Run the suspected zone and watch for water surfacing. The leak is usually at or near the wet spot, though water can travel along the pipe trench and surface several feet from the actual break.
• PVC pipe repair: Dig down to expose the break. Cut out the damaged section with a hacksaw, leaving clean square cuts. Use a repair coupling and PVC primer + cement to splice in a new section. Let cure 2+ hours before pressurizing. Materials cost: $5–$15.
• Poly pipe repair: For polyethylene pipe, cut out the damaged section and use barbed insert couplings with hose clamps to reconnect. Simpler than PVC but requires the right fittings for your pipe size.
• Freeze damage: If you're finding multiple leaks after winter, the system likely wasn't properly winterized. Check every zone thoroughly before assuming a single-point repair will fix everything.

When to Call a Professional

While many sprinkler problems are DIY-fixable, some situations call for professional help:

• Main line leak (between the water source and the valve manifold) — high pressure, high flow
• Backflow preventer failure — requires certified testing after repair in some cities
• Multiple zones with problems simultaneously — suggests a systemic issue
• Electrical problems beyond simple wire splicing
• Redesigning or adding zones — requires hydraulic calculations to avoid pressure issues
• Any work that requires digging near utility lines (always call 811 before digging)

NewHome Finishers connects you with vetted irrigation professionals across Idaho Falls, Pocatello, and Rexburg for fast, reliable repairs.