Why Is My Sprinkler System Not Working? 10 Common Problems

The short answer: most sprinkler complaints come down to one of ten things, and only about half are actual failures — the rest are design or set-up issues that were present from the beginning. The quickest way to narrow it down is to ask whether the problem affects one head, one zone, or the whole system. That single question eliminates most of the list.

Whole system will not run

1. The controller has lost its program or its power

Start here, because it is both the most common cause and the easiest to check. A power interruption can wipe a schedule on older controllers, and a controller left in the wrong mode after winter will sit there doing nothing. Confirm it has power, that it is not in an "off" or "rain delay" mode, and that a start time is actually programmed.

2. The water supply is still shut off

After winterization the irrigation supply is closed. If a system will not run at all in spring, the valve not being reopened is a genuinely frequent explanation — and a good reason to have the start-up done properly rather than piecemeal.

3. A failed rain sensor

A sensor that has failed in the "wet" position tells the controller it has rained, indefinitely. The system then never runs and the controller shows no fault. Sensors are inexpensive and are worth testing every spring.

One zone will not run

4. A failed valve solenoid

Each zone is opened by an electric solenoid on its valve. When one fails the controller advances through its cycle normally and that zone simply never comes on. It is a contained repair, but it is at the valve manifold rather than anything a homeowner can reach from the lawn.

5. A wiring fault to the valve

Buried wire, a corroded connection or a splice that has let water in all produce the same symptom. Aeration and digging are common causes — which is worth remembering before anyone puts a fork in the lawn.

6. Debris in the valve

Grit that has worked into the system can hold a valve partly open or stop it seating, which shows up as a zone that will not shut off properly or one that weeps continuously.

One head is the problem

7. The head is sitting below grade

The most common single finding in spring. Years of mowing and soil settling leave a head low, so it sprays into the grass around it instead of over it. The symptom is a soggy ring with dry lawn beyond it. Resetting heights is routine start-up work.

8. A blocked or worn nozzle

Grit blocks nozzles and years of use wear them, and both distort the spray pattern. A head that mists, dribbles, or throws a lopsided fan usually needs its nozzle cleaned or replaced rather than the whole head.

9. The head is out of adjustment or obstructed

Heads get knocked out of plumb or rotated, and planting grows in front of them. A shrub that has thickened over three seasons will block a head that used to clear it, leaving everything behind it dry — with nothing wrong with the system at all.

Everything runs, but the lawn still has dry patches

10. The zone has more heads than the water supply can run

This is the one that is not a failure, and it is behind more complaints than any mechanical fault. If a zone is asked to run more heads than the service can supply at proper pressure, every head throws short, the designed overlap between heads disappears, and dry rings appear between them. The system looks like it is working — water comes out of everything — so the usual response is to run it longer, which soaks the covered areas and leaves the gaps dry.

The fix is re-zoning rather than scheduling. How many zones a lawn needs explains how that number should be worked out.

What is worth checking yourself

Four things are safe and often solve it: confirm the controller has power and a programmed start time and is not in rain-delay; confirm the irrigation supply valve is open; look at the rain sensor; and walk each zone while it runs, noting any head that is low, blocked, misting or aimed wrongly. That walk-through is the single most useful thing a homeowner can do, because it tells whoever attends exactly where to look.

What is not worth attempting: anything inside the valve manifold, buried wiring, or charging a system you suspect has freeze damage. Running a cracked line under full pressure turns a repair into a flood.

How to avoid most of this list

Looking back over the ten, the majority are prevented by two seasonal visits and one habit. The visits are a proper spring start-up, which catches sunken heads, blocked nozzles, failed sensors and winter damage before the season starts, and a thorough fall blow-out, which prevents the freeze damage that causes the worst of the spring failures.

The habit is simply watching the system run once a month. Five minutes while a couple of zones cycle will show you a head that has dropped, a nozzle throwing oddly or a shrub that has grown into the spray — all of which are cheap to correct when caught and annoying when they are allowed to run all summer.

What tends to be a small repair and what does not

Without quoting figures that would be guesswork for your property, the general shape is this. Nozzle cleaning or replacement, resetting a head's height, re-aiming a head and replacing a rain sensor are small items, usually handled inside a normal service visit. A failed solenoid is a contained repair at the manifold. A wiring fault can be quick or slow depending entirely on where the break is, because finding it is most of the work.

Freeze damage is the expensive category, and it is also the avoidable one — which is the whole argument for having the blow-out done in October rather than hoping for a mild November.

When to stop and call

Three situations are worth a call rather than further investigation: water appearing at the surface where no head is running, which suggests a split line; a zone that will not shut off, which can waste a great deal of water quickly and usually means a valve is not seating; and anything you suspect is freeze damage. In the second case, shutting off the irrigation supply at the valve is the right first move.

One note on servicing: we happily service, repair, start up, maintain and winterize our existing clients' systems across the GTA. If you have a system installed by someone else and are only looking for seasonal maintenance, that is usually something we cannot take on. If an existing system needs upgrading or significant modification, we may be able to help — give the office a call and we will tell you straight away.

If a system has not been through a proper spring start-up or was not winterized correctly, start there — a large share of mid-season faults trace back to one of those two visits being skipped. Our service packages cover both, and the support and resources page has Hunter and Rain Bird controller manuals if you want to work through your controller's programming.