One day, about a year ago, I came home from work to find a geyser in our front yard. Water was shooting some five feet into the air, and had been doing so all day long, turning the lawn into a swamp.

Our landscape contractor quickly discovered the cause: a broken sprinkler head, which he easily replaced.

The problem was observed, diagnosed and repaired in under 30 minutes.

We got off easy. Unfortunately, when something goes wrong with an irrigation system, the cause isn’t always as dramatically obvious as in this example.

The process of figuring out the cause of a problem can be more like something out of that old doctor show, ‘House.’ In any episode, there were usually three or four incorrect diagnoses until the last ten minutes of the show, when grumpy old Doc House would finally figure out what was wrong with the patient.

The medical analogy is apt, said Tom Horn, owner and president of All-n-One Outdoor Solutions, Inc., in Jefferson City, Missouri, and a Rain Bird Academy instructor. The process of troubleshooting an irrigation system isn’t that different. You rule out one cause of a problem, then another, and another. If it isn’t cause A, B, or C, then it’s probably D.

According to Kurt K. Thompson, owner of K. Thompson and Associates, LLC, an outdoor water-use training, evaluation and planning company in Milton, Florida, problems with irrigation systems fall into three basic categories: electrical, mechanical or hydraulic.

“When something is physically not working, such as water not coming out, most people think it’s probably something electrical,” he said, “and it often is. But of the three broad classes of problems, hydraulic is the one that’s most overlooked.”

Before you attempt any troubleshooting assignment, you should have a few things in your doctor bag—er, toolbox. First, a good volt/ ohmmeter, to check voltage and resistance. Next, a wire locator, to help you track wiring paths, and a fault detector to find wire breaks. Finally, a set of wire strippers and splices for making repairs. For working on 2Wire systems, a clamp meter that reads out in milliamperes is essential.

Problem: turf or plant matter is dry, or dying

Either the system just isn’t irrigating at all, or one or more zones aren’t working. When an entire system isn’t working, the cause is often electrical. “We frequently see problems with power supplies,” said Horn.

If there’s no power to a system, first you need to determine if the cause is external, such as a power outage in the area. If the power is indeed ‘on,’ but the system isn’t, it may be that a power surge, such as a lightning strike, has tripped a circuit breaker or ground-fault circuit interrupter (GFCI).

If so, resetting the breaker or GFCI should fix it, unless there’s a problem with the breaker box or the GFCI receptacle itself, or an issue with the irrigation controller.

Problem: the controller’s display is blank

“We get a lot of customer calls about this,” says Horn. The first thing you check is that the controller has power to it. Believe it or not, technicians often find that controllers have simply been unplugged.

If it does have power, and the display comes on, then you need to check the settings, and go through each one to see if any of the zones will activate. If an entire zone doesn’t work, then it’s time to start thinking about a valve problem.

The valve to that zone may be stuck closed, have a shorted-out solenoid, or a damaged diaphragm.

Problem: the system is irrigating too much 

When Dustin Reitzer, irrigation manager at Green Thumb Landscape and Maintenance, Inc., in Salem, Oregon, is asked if there is a commonly-seen cause of problems in most residential irrigation systems, he starts laughing: “Yes, there is— the homeowner! He’ll get into that controller and, not understanding how it works, mess around with the start times.”

What typically happens is that someone will think he’s adding time to a single zone, when he’s actually added it to every zone. Most controllers can be set to start irrigating up to four times a day. A homeowner will set ‘start time 1,’ thinking he’s adding time to zone 1, and does the same thing with start times 2 – 4.

“Pretty soon, the entire system is kicking on four times a day, when he only wanted it to come on once,” said Reitzer. “He didn’t understand that you enter an ‘on’ time just once, and the controller automatically starts each zone back-to-back, in sequence.”

Problem: leaky or broken sprinkler heads

Leaks in irrigation heads are often misunderstood, according to Thompson. “People think that if a head’s leaking, then it must be broken. What they don’t understand is that water isn’t always present in the pipes, fully pressurized, 100 percent of the time.”

The problem is often a valve, specifically, a valve bonnet. “I’ve had homeowners replace a bunch of sprinkler heads, and then call me because they never stopped leaking,” Thompson said. “I replace the bonnet in the valve, and I’m in and out in 20 minutes, where they’d spent half a day trying to figure out what’s wrong.”

If the system is off, but sprinkler heads are leaking, it could be the result of a valve that’s become stuck in the ‘on’ position. It may not be closing because of something mechanical with the valve itself. If it isn’t any of those things, check the wiring that feeds it. If the wiring is intact, then the cause may be hydraulic.

If only part of a zone isn’t working, then it’s time to check for broken or damaged sprinkler heads.

These things are out in the sun, all day long, year after year. That takes a toll, as does the everyday wear and tear on the little gears inside of them. Anything with moving parts in it eventually fails.

Heads also get broken from people walking on or kicking them, or because landscape workers inadvertently hit them with edgers or run over them with mowers. Reitzer said that wiper seals, the little white plastic rings around the shafts of pop-up sprinklers, are often the first things to fail. The telltale sign is seeing water coming out around a popup’s head, but not out of its nozzle.

Problem: uneven coverage

A property owner or groundskeeper, walking along a lawn or turf area, notices a distinct pattern. While most of the turf looks green and lush, one particular area seems to be suffering, with brown spots or discoloration.

The first step is to go to the controller and activate the affected zone. Observe the sprinklers. Is the trajectory of one or more of the heads off-target, or is plant material blocking the spray?

If it’s not immediately obvious what the source of the problem is, go to each head that should be hitting those browned areas, and inspect them. You may need to adjust their arcs and radii. Sprinkler heads may have sunk over time or become tilted. Nozzles can break, too.

A homeowner may have played around with one or more sprinkler heads, attempting to adjust the throw. “The edge of a lawn will be brown, an obvious sign that it’s not getting water,” said Reitzer. “So, he’ll try to open up the head a little more, to make his lawn look nice and green.”

“But he doesn’t really understand the mechanics of it,” Reitzer continued. “For instance, most people don’t realize that only one side of the arc can be adjusted by turning that little screw.”

If he was baffled by regular pop-up sprinklers, a non-professional will really be out of his league with rotors. Adjustment of these types of sprinklers is a kind of art, Reitzer said, “because there are so many different types available.”

“One model will have the left stop adjustable, but on another, it’ll be the right stop. For another brand, you turn the entire body clockwise. So, a property owner will try, struggle, fail, and then finally, call us.”

Thompson says that the most overlooked factor in sprinkler performance is the water source itself.

“When you see performance problems, it’s usually a pressure or flow situation. These are often built in, at the time of construction.”

The system could have been changed over time, and on an older property, probably has been. Components require a certain pressure in order to run properly, and may no longer be getting it. Also, as neighborhoods add more homes, water pressure often decreases.

Sprinkler heads could have been added. Changing the types, sizes and numbers of sprinklers or nozzles will alter their hydraulics, and that’s going to affect performance. For instance, if you have a rotor that needs 55 psi to run optimally, then you’re going to need more than 55 psi at the source, because some pressure will be lost by the time the water gets all the way out to the rotor itself.

Those rotors might have worked fine when they were first installed. But if some additional rotors were added later, without increasing the water pressure, none of them will function the way they’re supposed to.

Problem: underperforming drip, micro or low-flow system

Locating and determining a problem in a micro sprinkler or low-volume system would be done in pretty much the same way as a conventional one, since both types employ sprinklers.

Drip is a little different. As with other coverage issues, the first indication of malfunction in a drip system usually comes when plant material starts looking bad. The problem is generally either mechanical or hydraulic in nature. Power isn’t always a factor, unless a valve to the drip system is electrically closed.

“In drip, the classic problem is that water isn’t coming out of most or all of the emitters,” said Thompson.

“But it can be difficult to pinpoint precisely where you’re losing water pressure, because dripline and emitters are often covered with mulch, decorative rock, or weed-barrier fabric.”

“The tubing could have been cut by a tool, or chewed on by an animal,” said Reitzer. “Or, the sun has made the tubing so brittle over the years that it finally split.”

To diagnose, you first identify the beginning and endpoints of the dripline. The valve will be found at the beginning point.

The next step is to test the pressure at the end of the line, to see if it’s fairly close to the pressure at the beginning. A big difference in pressure could indicate a leak or collapsed tubing.

Tubing or emitters could also have become plugged by water contaminated by debris. Micro, drip and lowvolume emission devices, because of their small orifices, are more susceptible to particulate clogging than rotors or sprays. “The smaller the hole the water has to go through, the more chances of problems with dissemination,” said Horn.

That’s why these types of systems need good filtration. If lines or emitters are clogged, the filters may need cleaning, and if they are not present at all, you should install them. Filtration is especially important if a system draws dirty, particle-filled water from a lake, pond, river, or an outlet pipe for reclaimed water (partially treated sewage water that’s safe for irrigation, but not for drinking).

Another thing that micro, drip and low-volume systems need is pressure regulation, as they’re designed to operate at much lower pressures than conventional components. Emitters have been known to pop right out of dripline when subjected to water pressure that’s too high.

Problem: 2Wire system malfunction

The troubleshooting of 2Wire systems deserves its own article, but we’ll touch on it here. First, determine that water is flowing, and that the controller is putting out power. Go to the last valve that doesn’t work, then to the last valve that does. The problem probably lies somewhere along that path—a broken wire, decoder or valve.

If a decoder has power, then its valve should open. If it doesn’t, then the problem is within that valve.

The great thing about 2Wire systems is that they’re self-diagnosing. For instance, if you suspect a problem with an individual decoder, you simply unplug it from its location, and plug it into the back of the irrigation controller. The controller’s ‘fault log’ should give you a detailed description of what’s going on with the system, and scroll it right across its screen.

If you’re fortunate enough to have an ‘as-built,’ a map of the irrigation system, your detective work will be much easier. Unfortunately, these are usually only created for large commercial systems.

As-builts for residences are rare, so if you think the wire might be broken, you’ll need to break out the wire trackers and fault finders, if you suspect a short somewhere.

When you don’t have a map, then you may have to do some digging, literally. Thompson relates a story about a valve hunt he was recently forced to go on at a residence.

He and his ‘right-hand’ irrigation tech spent 12 man-hours one day looking for six valves. “This guy is probably the best electrical and wire tracker on the planet, and I’m pretty doggone good at it myself. Taking this long to find six valves is just outrageous, but it happens regularly.”

If you want to learn more, there are plenty of educational opportunities out there, through the Irrigation Association, other green industry associations, colleges and irrigation manufacturers. With some education, persistence and experience, you might even become as adept as Dr. House at diagnosing any ‘illness’ an irrigation system can throw at you.