Overview: Simple system, easy fixes
An automatic lawn irrigation system
is the best way to keep your
lawn looking fresh and green.
Correctly designed and programmed,
it'll deliver the right amount of water to your yard—
no more moving the sprinkler! But like any other system, it
occasionally breaks down or requires maintenance.
The good news is you can handle 90 percent of the repairs
yourself, even without in-depth knowledge of the system. We'll
show you how to identify and fix the most common problems.
Calling in a professional could cost at least $100, even for a
simple problem you can fix yourself in 10 minutes.
Don't be intimidated by the prospect of working on a system
that involves both plumbing and electricity. The pipes are plastic
and much simpler to repair than the plumbing in your
house. The electrical lines are low voltage, so they're not
hazardous. You don't need special skills to make the repairs, but you'll
need a multimeter to diagnose electrical problems.
Figure A: How a sprinkler system works
Figure A: How a Sprinkler System Works
The controller sends a signal to the control valves in the control
valve box. The valves open, sending water through the underground
water line, which causes the sprinkler heads to pop up and spray.
Sprinkler heads not working? Solution 1: Replace the heads
1 of 1
Replace a sprinkler head
Dig around the sprinkler head to expose the riser.
Unscrew the broken sprinkler head from the riser.
Install the new head, turning it tight with your hands.
Broken sprinkler heads are easy to identify. Simply
look for cracked or broken plastic casing on the
heads, heads that don't pop up, or water that sprays wildly
or not at all. It's common to find the top of the head
completely broken off. This typically happens to heads
that are set too high and are run over by vehicles or hit by
Replacing the head is one of the simplest fixes.
Replacement heads are available at home centers and
online. Be sure to buy the same type of
head that you're replacing.
To change a broken head, turn off the system and dig a
2-ft.-diameter hole around the head. Using a square
shovel, slice the sod into easy-to-remove pieces. Set the
sod on a tarp so you can set it back into place at the end
of the job.
Dig down to the “riser” (the vertical pipe that branches
off the main line) which is connected to the sprinkler
head. Dig with a light touch to avoid damaging the plastic
water line, which is 8
to 12 in. underground.
Turn the head counterclockwise
it from the riser. While
the head is off, take care
not to spill dirt into the
riser. Sprinkler heads
are installed only hand-tight,
but after being in
the ground for several
years, they may require the use of wrenches to unscrew.
If the head doesn't turn easily, hold the riser with slip
joint pliers to keep it from twisting loose from the fittings
Attach the new sprinkler head by placing it on the riser
and turning it hand-tight (photo). Don't use Teflon
tape or joint compound on the riser threads.
Sprinkler heads are factory tested to make sure they
work. As a result, they're often packaged still wet, so don't
be surprised to see water in a new head.
Before filling in the hole and replacing the sod, set the
desired sprinkler pattern (see “Reset the Spray Pattern,”
Before you start digging
to access the underground
water lines, electrical wires
or spray heads, dial 811 to have
your underground utility
lines identified and marked.
Sprinkler heads not working? Solution 2: Clean and reset heads
1 of 3
Photo 1: Unscrew the top
sprinkler head by
unscrewing the top
from the canister. Rinse
away soil and debris in
a bucket of water.
2 of 3
Photo 2: Clean the screen basket
Remove the screen
basket from the
bottom of the head,
then clean it with
3 of 3
Photo 3: Adjust the spray
Adjust the watering range of the sprinkler head
before installing it. Place the head in the canister
so the nozzle is at the edge of the area to be watered.
Make final adjustments with the water running.
Dirt sometimes gets inside sprinkler heads, causing
them to clog up. Clogged heads may rise but fail to
spray, not lower after watering, or produce an erratic
To clean the head, dig it out and remove it from the
Riser (Photo above). Take the head apart by holding the bottom
of the canister and turning the top of the head counterclockwise.
Once it's unscrewed, lift it out of the canister
Remove the plastic screen basket, which serves as a filter,
at the base of the head. If you can't pop the basket out
with your fingers, pry it out with a flat-head screwdriver
or pull it free with a pliers. Rinse the basket in a bucket of
clean water, washing out the debris (Photo 2). Clean the
rest of the sprinkler head by rinsing it with water. Replace
the head on the riser. If it still doesn't work, replace it
with a new head.
Note: In areas of the country that
experience freezing temperatures,
pipe is used for the irrigation
water lines. PVC pipe is
used in areas that don't freeze.
Reset the spray pattern
When putting on a new sprinkler head or using the same
head after cleaning, you may need to adjust it to water a
specific area. Adjustment methods vary. You can adjust
some head types by turning a slot at the top with a screwdriver.
Others require a special key that you insert into the
head and turn (Photo 3). Some heads also allow you to
adjust the spray pattern by turning a tiny screw located next
to the nozzle.
Adjust the heads before installing them, then fine-tune
them once they're in place with the sprinkler running.
First, turn the top clockwise until it stops. That nozzle
location is the starting point (the head will turn counterclockwise
Adjust the head to set
the watering rotation
anywhere from 40
degrees to 360 degrees
the starting point.
Set the head in the
canister. Standing behind
the head, align the nozzle
with the right edge of the area you want to water, such as
along a driveway. Tighten the head in the canister. Carefully
backfill the hole and replace the sod.
Turn on the sprinklers at the controller. Allow the head
to make a few rotations, then make additional adjustments
while the system is running.
Low water pressure? Solution 1: Turn on valves at backflow device
1 of 1
Check the valves
Check the valves on the
backflow device to make
sure they're open. Turn
the valve on the horizontal
pipe first, then the vertical
Low water pressure will result in the
sprinkler heads barely shooting
water. In extreme cases, many of the heads
won't even pop up. Start with the easiest
solution. Make sure the valves at the backflow
device are fully open. The backflow
device is located above ground, with the
valve at least 12 in. above the highest
sprinkler head in the yard. Most backflow
devices have a valve on the horizontal and
vertical pipes. Turn the valves to their open
positions as shown. The valve is open
when the handle is parallel with the pipe.
Low water pressure? Solution 2: Find and repair leaks
1 of 2
Photo 1: Install a slip coupling
Cut out the damaged section
of line and replace it
with a slip coupling.
Secure the coupling with
2 of 2
Photo 2: Close-up of slip coupling
A slip coupling easily
expands and contracts
to replace a damaged
section of line.
Then check for leaks in the water line.
Look for a series of sprinkler heads
that aren't watering properly. The water
line problem is always located between the
last working head and the first nonworking
Look for signs of leaking water, such as
water bubbling up from the soil when the
sprinklers are running, a depression in the
ground, or a very wet area. If you find running
water, follow the water to the highest
point to find the source.
Once you locate the approximate leak
site, dig straight down to the water line.
Then enlarge the hole along the line, following
the flow of the leaking water until you
find the break or crack. Before making the
repair, make sure the system is turned off at
Use a slip coupling to repair the leak.
This special coupling contracts to make
insertion easy. Find these couplings and other repair parts at irrigation supply
To fix the leak, use a hacksaw to cut out
a 4-in. section of line at the leak. Place a
clamp on one of the line ends, insert the
coupling, then tighten the clamp.
Place a clamp on the second pipe end,
expand the coupling while inserting the
nipple into the pipe, then tighten the
clamp. Backfill the hole with dirt and
replace the sod.
Low water pressure? Solution 3: Repair crushed pipes
1 of 2
Photo 1: Crushed pipe
Tree roots can grow around a pipe and squeeze it closed after several years.
2 of 2
Photo 2: Splice in new pipe
Cut out the damaged section of line.
Replace it with a new section of line,
making connections with standard
couplings and band clamps.
If you can't locate a leak, the water
line may be crushed or obstructed.
Sometimes, roots wrap around the
line and squeeze it closed over the
course of several years (photo 1).
Or vehicles may have compressed the
soil and collapsed the line. These problems
are harder to find and often require
a lot of digging. Again, look for the
problem after the last working head. Dig
along the water line until you find the
damaged section. If the line runs near a
tree, start your digging there.
Once you locate the damaged section,
cut it out with a hacksaw. If the
line was damaged by tree roots, reroute
the line by digging a new trench away
from the tree.
Cut a new section of pipe to replace
the damaged one. Then replace the section
of pipe, connecting it at each end
with regular couplings and band
clamps (photo 2).
Zone not working? Solution 1: Check for voltage to the bad zone
1 of 1
Check for low voltage
Check the voltage to the nonworking zone
using a multimeter. Touch the leads to the
common terminal and zone terminal. If the
voltage is too low, replace the controller.
Your watering system is divided into a
series of zones. Each zone has an
electrically activated valve that controls the
heads for a designated area.
Generally, if you have a zone that's not
turning on, you have an electrical problem.
To solve the problem, make sure the zone
wires are firmly attached to the terminals
in the controller, the transformer is
plugged in, and the circuit breaker at the
main panel is on.
Next, test for voltage to the nonworking
zone, using a multimeter (at home centers
and hardware stores). Turn on the nonworking
zone at the controller. Turn the
multimeter dial to voltage and place one
lead on the common terminal (marked “c”
or “com”). Place the other lead on the terminal
of the zone that's not working (photo
left). It doesn't matter which lead goes to
Refer to your owner's manual to see
whether the voltage reading falls within the
required range (usually 24 to 28 volts). If it
doesn't, the controller needs to be replaced.
(If you don't get any voltage reading, see
“Check Fuse and Transformer,” below.)
Fortunately, controllers rarely go bad
unless struck by lightning. New ones start at
$175 and can cost upward of $400. Replace a
damaged controller with the same brand
and model as you currently have. To replace
it, label each wire that's connected to the
controller with a piece of tape. Unhook the
wires, then attach them to the new controller
in the same sequence.
Zone not working? Solution 2: Check fuse and transformer
1 of 1
Test the transformer
Test the transformer voltage
by placing the multimeter
leads on the transformer terminals
marked “24 vac” with
the transformer plugged in. If
the reading is less than 22,
replace the transformer.
If no zones will turn on, first turn the controller to the manual
setting to see if the system will run. If it turns on manually, the
controller is good but the rain sensor may be stopping the automatic
programmed watering, which is what it's designed to do.
Rain sensors conserve water by preventing the system from running
when the ground is already saturated and doesn't need additional
watering. Some states require rain sensors on all new systems. (Your
rain sensor is bad if the system runs when the ground is already wet.)
If the system doesn't run in the manual position, check the controller
for power. If it has a fuse, make sure it's not blown. Or, if it
has a circuit breaker reset button, press the button, then try the
system again. If the system is plugged into a GFCI receptacle,
press the GFCI reset button.
If it still doesn't turn on, make sure the outlet that the power
transformer is plugged into is working by plugging in a power
tool. If it's working, plug the transformer back in, turn the system
off and test the transformer for voltage. Using a multimeter, place
a lead on each of the two transformer terminals. It doesn't matter
which lead goes to which terminal.
The transformer terminals are marked “24 vac.” A 24-voltage
transformer should normally test between 24 and 28 volts. If the
voltage falls below the manufacturer's range, replace the transformer. Simply unscrew the terminals that hold the two
transformer wires in the controller and remove the transformer
(photo). Insert the wires on the new transformer through
the designated opening in the
controller. Attach the wires to
the controller terminals marked
“24 vac” by placing the wire
ends under the screws, then
Zone not working? Solution 3: Replace defective valve
1 of 3
Photo 1: Replace the solenoid
Disconnect the wires and
unscrew the defective solenoid
from the control valve. Insert a new
one and turn it until it's finger-tight.
2 of 3
Photo 2: Reconnect the wires
Connect the two wires on the
new solenoid to the common
wire and a field wire, using waterproof
3 of 3
Photo 2A: Waterproof connectors
Special connectors are filled with silicone to make the connections waterproof.
If the controller, fuse and transformer check out OK,
test the resistance “ohms” between the common
terminal and the nonworking zone. Turn off the system,
turn the multimeter to test for ohms (the omega symbol),
and place the leads on the common
terminal and zone terminal,
just as you did to
test for voltage.
Compare the ohms
reading with the range listed in
your owner's manual (usually 20 to 60
ohms). If the ohms fall below the
required amount, the switch
(solenoid) that operates the
control valve for that zone is
defective and needs to be
replaced. The defective solenoid will
be connected to the same color wire as
the zone wire at the controller. (If the
reading is too high, see “Repair Damaged
Control valves are typically grouped
with three to six valves in one box (Photo
1). The boxes are located in the ground
with a cover that simply lifts off. They
can be located anywhere in the yard but
are usually close to the main water
Although valves themselves rarely need
to be replaced, solenoids do occasionally
fail. Replacing them is quick and easy.
Be sure the controller is in the off position
(you don't need to shut off the
power) and the water valves on the backflow
device are turned off. Inside the control valve box,
remove the wire connectors and disconnect
the two wires on the defective solenoid
from the common and field wires.
Turn the solenoid counterclockwise to
unscrew it from the valve (Photo 1).
Water will slowly seep out of the valve
opening, even with the water turned off.
Place a new solenoid in the valve and
turn it until it's finger-tight.
Twist the ends of the new solenoid
wires onto the same common and field
wires that the old solenoid was attached to
(Photo 2). It doesn't matter which solenoid
wire goes to the common and which
one goes to the field wire. Twist a new
waterproof wire connector over each connection
(Photo 2). To make waterproof
connections, use a silicone-filled “direct
bury” connector (Photo 2A), available at home centers.
Repair damaged wires
If the ohms reading between the common
terminal and nonworking zone terminal is
too high (it's sometimes an infinity reading),
the problem is a severed or bad wire
to the control valve. If only one zone isn't
working, the field wire is damaged. If none
of the zones in a control valve box is
working, the common wire is damaged,
although the field wires could also be bad.
To find a bad wire, bypass each in turn by
temporarily substituting a 14-gauge wire
for the original that you run above ground.
Make the wire connections with the controller
turned off. Then turn the controller
back on. Test the field wire first. If the zone
turns on, the old field wire is bad. Replace it
with an 18-gauge wire rated for underground
burial. Bury the wire at least 8 in.
underground. Follow the same procedure
to test the common wire.