Troubleshooting Common Sprinkler Problems

Most sprinkler problems trace back to a handful of causes — a clogged nozzle, a partially closed valve, a bad solenoid, or heads spaced too far apart. This guide walks each symptom to its likely cause and the fix, so you can diagnose in the right order instead of guessing.

How to diagnose in the right order

Before diving into a specific zone, rule out the whole‑system basics: is the main water supply fully open, is the controller powered and programmed, and has anything changed recently (new plantings, a mower incident, a freeze)? Working from "affects everything" toward "affects one head" saves time. Keep this table handy as a quick index, then read the detailed sections below.

Symptom	Likely cause	First fix to try
Weak spray / low pressure	Too many heads per zone, closed valve, clog, leak	Clean nozzle & filter; fully open supply valve
Dry spots / uneven coverage	Bad spacing, wrong nozzles, tilted heads, wind	Check head‑to‑head spacing and nozzle sizing
Head won't pop up or retract	Debris, low pressure, broken riser	Clear grit; check zone pressure
Zone won't turn on	Wiring, bad solenoid, no common wire	Test solenoid & wiring at the valve
Zone won't shut off	Debris in diaphragm, stuck solenoid	Clean valve diaphragm; tighten solenoid
Leak or geyser	Cracked pipe, broken head	Locate wet spot; replace head or pipe
Controller not running	Power, programming, rain sensor	Check power, program, and sensor override

Low pressure or weak spray

Symptoms: heads barely dribble, rotors turn slowly or not at all, spray doesn't reach as far as it used to.

Likely causes: too many heads on one zone for the available flow; a supply or zone valve that's only partly open; a clogged nozzle or dirty inline filter; or a hidden leak bleeding off pressure.

Fixes:

• Confirm the main and any backflow shutoff valves are fully open — a half‑closed valve is a classic culprit after any recent plumbing work.
• Unscrew a head's nozzle and rinse it; pull and clean the small filter screen at the base of the head.
• If every head on a zone is weak, the zone may simply have more heads than your flow can support. Check your numbers with water pressure and GPM and, if needed, split the zone using how to calculate sprinkler zones.
• A sudden pressure drop with a soggy area points to a leak — see the leaks section below.

Dry spots and uneven coverage

Symptoms: brown patches between green ones, one corner always dry, coverage that looks fine up close but leaves gaps.

Likely causes: heads spaced too far apart, the wrong nozzle arc or radius, heads tilted or sunk below grade, or wind drifting the spray.

Fixes:

• Sprinklers are designed for head‑to‑head coverage — each head's spray should reach the next head. If yours don't, you likely need closer spacing or larger‑radius nozzles. See sprinkler head spacing.
• Check that each head sits vertical and flush with the soil; straighten tilted heads and raise sunken ones.
• Match nozzle radius and arc to the area — a quarter‑circle nozzle throwing into a full‑circle spot leaves gaps. Compare options in spray, rotor, and drip heads.
• If dry spots only appear on windy days, shift watering to early morning when wind is calmest.

Heads that won't pop up or retract

Symptoms: a pop‑up stays down while others rise, or a head won't sink back after the zone shuts off.

Likely causes: grit binding the riser, low zone pressure that can't lift the head, or a cracked/broken riser stem.

Fixes:

• With the zone off, gently pull the riser up and down and flush out dirt; clean the wiper seal at the top of the body.
• If the whole zone is low on pressure, the heads may not have enough force to pop up — solve the pressure issue first (above).
• A head that won't retract usually has debris under the spring or a broken internal — replace the head; they're inexpensive and swap in minutes.

A zone that won't turn on

Symptoms: the controller says a zone is running, but nothing happens at the heads.

Likely causes: a wiring fault between controller and valve, a failed solenoid on that valve, or a broken/disconnected common wire.

Fixes:

• First test whether the valve itself works: at the valve, gently open the solenoid a quarter turn (or use the manual bleed screw). If water flows, the valve is fine and the problem is electrical — wiring or controller.
• Inspect wire connections at the valve and controller for corrosion or breaks; outdoor splices should use waterproof connectors.
• A single dead zone often means a bad solenoid — unscrew and replace it. If no zones fire, suspect the common wire (shared by all valves) or controller power.

A zone that won't shut off

Symptoms: water keeps running after the controller ends the cycle, or a zone runs even with the controller off.

Likely causes: debris caught in the valve's rubber diaphragm holding it open, or a stuck/failing solenoid.

Fixes:

• Shut off the water, open the valve body, and clean the diaphragm and seat — a tiny piece of grit is the usual offender.
• Make sure the solenoid is snug and fully seated; a loose solenoid can weep and keep the valve cracked open.
• If cleaning doesn't help, replace the diaphragm (repair kits are cheap) or the whole valve.

Leaks and geysers

Symptoms: a fountain of water where a head should be, a constantly soggy patch, or a zone that never builds pressure.

Likely causes: a head snapped off (often by a mower or vehicle) or a cracked underground pipe/fitting.

Fixes:

• A geyser at a head is the easy case — unscrew the broken head and thread in a matching replacement.
• A soggy area with no visible break usually means a cracked lateral pipe. Run the zone, find the wettest spot, and dig carefully to expose and replace that section.
• After any freeze, cracked pipe and backflow damage are common — see how to winterize a sprinkler system to prevent it next year.

Controller not running at all

Symptoms: blank display, or the schedule never starts.

Likely causes: lost power, a tripped breaker or dead backup battery, a programming error, or a rain/freeze sensor holding the system off.

Fixes:

• Confirm the controller has power — check the outlet, breaker, and transformer.
• Verify the program: correct start time, run times, days, and that the dial isn't set to "off." A common gotcha is an accidental second program or an A/B/C schedule conflict.
• If everything looks right but nothing runs, a rain or freeze sensor may be tripped — check its status and any bypass switch.
• Revisit your watering schedule to make sure the program matches the season.

Most of these fixes take minutes and a few dollars in parts once you've correctly identified the cause. If you're troubleshooting a system that was never quite right to begin with — chronic dry spots, zones that can't keep up — it may be a design problem, not a repair. Design your system from a satellite photo to check your spacing and zoning, or start from how to design a sprinkler system.