Sprinkler Zone Repair & Troubleshooting

A zone is the basic unit of an irrigation system: one valve, one lateral line, and the group of heads fed by it. Systems are divided into zones because a typical house does not have enough flow to run every head at once, and because different areas have genuinely different watering needs.

The great advantage of that design is diagnostic. Because each zone has its own valve and its own pair of wires, a single failed zone tells you immediately that the shared parts — the water supply, the mainline, the controller’s power supply, the common wire — are all fine. The fault is in the four things unique to that zone: its station on the controller, its wire run, its solenoid, or its valve. That narrows an intimidating problem to a short list.

When all zones fail, the logic inverts: now it is the shared parts, and you are looking at the water supply, the controller power, the common wire or the mainline.

Symptoms homeowners notice

• One zone does not run at all while every other zone works
• One zone runs but will not shut off
• One zone is noticeably weaker than the others
• A zone that starts, runs briefly and then stops
• Two zones running at the same time when one was programmed
• The controller shows a fault or short circuit on one station
• A zone that only runs when the valve is opened by hand
• A zone that runs at some start times but not others
• Nothing at all runs on any zone

The most likely causes

• Failed solenoid. The most common single-zone failure. The coil burns out or its leads corrode in a wet valve box, so the valve never receives a usable signal.
• Cut or corroded field wire. Two wires run underground to each valve. Fence posts, sod cutters, aerators, planting holes and rodents break them. A nicked wire in wet clay corrodes over weeks, so the failure often appears long after the damage.
• Failed valve. A blocked bleed port or seized diaphragm stops the valve opening; debris on the seat or a torn diaphragm stops it closing.
• Dead station on the controller. One station output fails while the rest of the controller works normally.
• Broken common wire. Every valve shares a common return wire. A break in it kills every zone downstream of the break, which is why a "whole system down" fault is often one damaged wire.
• Programming. A zone with no run time assigned, a zero-minute duration, an active rain delay, or a station excluded from the program. No hardware fault at all.
• Lateral line break on that zone. A large break downstream of the valve dumps the zone’s water into the ground, so heads barely rise. The zone is "working" and still not watering.
• Manual bleed left open. A bleed screw opened during earlier testing and never closed leaves the zone running continuously.

How a technician diagnoses it

• Single-zone faults are the most satisfying irrigation problem to diagnose because the process is genuinely deterministic.
• Step one is the program, because it costs nothing. Does the zone have a run time, is a rain delay active, is seasonal adjust at zero, is the station excluded.
• Step two is voltage at the controller. With that station manually running, we measure across its terminal and common. Roughly 24 volts AC means the controller is doing its job and the fault is outdoors. No voltage means a dead station output or a controller problem, and we move to controller diagnostics.
• Step three is resistance on the field pair with the power off. A reading in the expected range means wire and solenoid are both intact — which points at the valve mechanically. An open reading means a broken wire or a dead coil. A near-zero reading means a short, and that short is what has been tripping the controller.
• Step four is the manual open test at the valve. If the zone runs beautifully when the valve is opened by hand, the hydraulics are fine and the problem is definitively electrical. If it will not run even then, it is the valve or the supply to it. Two measurements and one manual test isolate the fault in the large majority of single-zone calls.

What the repair involves

1. Read the program. Run times, rain delay, seasonal adjust and station assignment checked before any tools come out.
2. Measure at the controller. Voltage at the station terminal, then resistance on the field pair, to place the fault indoors or out.
3. Locate the valve. Accessible boxes opened; buried or undocumented valves found with a valve locator instead of exploratory digging.
4. Manual open test. Opening the valve by hand separates an electrical fault from a mechanical one in under a minute.
5. Trace wire faults. Where the pair is open or shorted, the wire run is traced with a locator to the break rather than guessing at a route.
6. Repair the actual fault. New solenoid, valve rebuild, wire splice with waterproof gel connectors, or controller repair — whichever the testing identified.
7. Run the zone and the neighbours. The repaired zone is cycled several times to confirm it opens and closes, and adjacent zones are checked in case the same damage affected more than one wire.

What affects the cost

Zone repair cost is driven by how far the fault is from the controller and how accessible the valve turns out to be.

• Whether the fault is electrical at the valve (usually quick) or a wire break somewhere along the run (variable)
• Whether the valve is in a known accessible box or has to be located
• Distance from the controller to the valve, and whether the wire route is documented
• Whether the repair is a solenoid, a valve rebuild, a full valve replacement or a wire splice
• How many zones are affected — a broken common wire can take out several at once
• Number of separate faults on the system, which older installations often have
• Excavation depth and soil conditions where digging is needed

For published rates and general North Georgia market ranges by repair type, see the Georgia irrigation repair cost guide.

Does this repair require digging?

Often none. If the valve is in an accessible box, replacing a solenoid or rebuilding the valve happens entirely from the surface.

Digging is needed to reach a buried valve with no box, to expose a wire break for splicing, or to cut out and replace a valve body. Locating first is what makes those holes small: a valve locator finds the solenoid and traces the wire to the break, so we dig one targeted hole rather than trenching along a guessed route. Any excavation is backfilled and the turf reseated, and where we expose a valve that had no box we fit one so the next service call is a lid-lift instead of a dig.

How long does it take?

The diagnosis itself is usually quick — controller measurements and a manual valve test take minutes. A solenoid replacement in an accessible box is typically well inside the first hour on site.

The variable is locating. Finding a buried valve or tracing a wire break across a large property can take longer than the repair. Valve replacements add time for glue joints to set before repressurising. We will tell you on site if a zone fault looks like a locating job before the clock runs.

Should the water be shut off?

A zone that will not turn on is losing no water, so there is no urgency — set the controller to OFF if you prefer and wait for the appointment.

A zone that will not shut off is the opposite. If it keeps running with the controller off, the valve is passing water mechanically and the only thing that stops it is closing the irrigation isolation valve. Do that first, then call.

Will leaving it alone raise the water bill?

A dead zone does not raise the bill, but it does cost money in a different currency: turf that dies and has to be resodded is far more expensive than the solenoid that would have prevented it. In a North Georgia July, a zone left off for a few weeks can lose a section of lawn.

A zone that will not shut off, or a valve weeping into a lateral, absolutely raises the bill, and continuously rather than only during programmed run times. Those are worth treating as urgent.

There is also a hidden cost to leaving one zone dead: people compensate by extending run times on the working zones, which over-waters most of the lawn to make up for a section that is getting nothing.

North Georgia considerations

The single most common cause of a suddenly dead zone in these neighbourhoods is other people’s work. Fence installation, mailbox and sign posts, deck footings, tree and shrub planting, sod replacement and aeration all put steel through shallow wire and pipe. When someone tells us a zone died the week after a fence went in, the fence is almost always the answer, and the break is almost always within a few feet of a post.

Wet clay is the aggravating factor. A wire that was only nicked rather than cut sits in damp soil and corrodes, so the zone works fine for weeks and then fails intermittently before dying completely. Intermittent zone faults on a system with a history of landscaping work are wire faults far more often than valve faults.

Valve boxes disappearing under successive rounds of new mulch and sod is the other local reality, which is why valve locating equipment does more work here than on newer developments where the as-built is still in a drawer somewhere.

Frequently asked questions

Related services

Where we do this work

Irrigation Medics covers Hall County and the Lake Lanier communities, the Gwinnett corridor through Duluth, Suwanee and Buford, and North Fulton and Forsyth. Rates are the same everywhere — see the full service area.