Troubleshooting Sprinkler Systems

Lawn and Garden Sprinkler Troubleshooting Guide

Backflow Device

Water shoots out of the top of the device.

Water shoots out of the top in a thin spray.

Water seeps from top of unit.

Check the bonnet kit for cracks and debris in the seal and seat, “O” ring or entire bonnet kit failed replace if necessary. Screw the old bonnet kit out. Screw the new bonnet kit in. Use a small amount of lubricant on the “O” ring. Hand tighten only.

Backflow device will not seal

Close both valves (blue or green handles) on the back flow device.  Turn both valve handles clockwise to the stop at the off position with the handles perpendicular to the valve. Then open the first valve on the backflow device. Just follow the pipe from the house to the first valve in line, quickly turn the handle counter clockwise to the fully open position with the valve handle parallel to the valve. This will build pressure and seal the bonnet kit unless it is damaged.

To charge the valves in the valve boxes. On the back flow device, slowly crack open the second valve 1/8th of a turn. If you lose the seal on the bonnet kit, close the 2nd valve again. Check for open drains in the valve boxes, zone valves manually or electronically turned on, leak in the main line can cause this problem.

Replace bonnet kit if needed.

The back flow device requires around 40 psi from the house to pressurize.

Water drips from test cock valve

Slowly rotate screw driver slot to the off position or perpendicular to the test cock valve. Replace the test cock valve if necessary. Unscrew the bad valve, then screw in the new valve with 7 to 10 wraps of plumbers tape.

Test cock valve drips when the system is in the winterized condition. Replace the sprinkler main tap inside the house if necessary.

Butterfly Valves on the back flow device

Water sprays out of the butterfly valve

Water sprays out the side when the handle is turned

Check for a hairline crack on the butterfly valve. Replace the butterfly valve or backflow device as needed. If you have this problem every spring. It can be caused by not being winterized properly, or the sprinkler main tap inside could be passing water while in the off position.

Water drips from butterfly valve handle

Remove the butterfly valve handle and slightly tighten the nut behind the handle with a small wrench. Over tightening this nut will not allow the handle to rotate. Spray rusty nuts with penetrating fluid for easy removal. Careful the nut can bust off if over torqued and then the valve will likely need to be replaced.

Controller or timer

Controller will not run

Program lost check program for start time, run days and run times.

Check electrical supply.

Check for a blown fuse or tripped reset.

Check rain sensor or turn it off on the controller.

Back up battery saves the program only, and will not run the zones.

Controller blinks and/or stops at a zone

Tends to be a shorted valve solenoid in the valve box outside. Check the zone valve that trips the controller.

Lost Program caused by loss of power,replace back up battery or do not unplug controller.

Digging for Problems

Always call for utility locates before digging. To get a professional restoration first cut the sod in a square rectangle or circle by inserting the shovel about 4” into the ground. Then pry up the sod until it can be rolled over and placed next to the hole. Then put down a tarp or something to put the dirt on. Carefully dig around the pipe or head to avoid damaging the pipe. Give yourself plenty of room, the bigger the whole the belter the repair. To back fill, replace the dirt in the whole making sure it even and level. Then roll the sod back into the same position that it was previously in. Step on the bump to compact. You can add water to compact or use a tamper to compact the dirt down. A rubber mallet makes a good compaction tool.

High Water Bill

Leak in valve box, leak in main line pipe, zone valve passing water or stuck on.

Before running the system, check for water in valve boxes, puddles around heads, water running down the street and wet areas. You can also check and see if your city water meter is running before and after you shut off the sprinkler main turn-on. If the city water meter continues to run while the sprinkler main tap (or sprinkler turn-on) is shut off, it is not the Sprinkler system causing the high water bill.

If your water bill doubles it can be caused by many things, sometimes it is how often you run the sprinkler system. Sometimes it is a leak in the main line pipe of a sprinkler system, or a lazy zone valve that takes hours to shut off after running. The main line pipe goes from the sprinkler main turn-on inside the house, to the valves in the ground. The main line pipe is under water pressure all the time 24 hours a day 7 days a week and can leak 24/7. Causing huge water bills. Many cities will give you a break on the water bill when you prove you fixed the problem. 

Down line drainage is when a zone pipe has residual water leak out after the zone runs, causing water to puddle around a head or running down the street. This normally dries up within a couple hours of running the zone. Down line drainage can be mistaken for a leaking zone valve.

Zone valve repair

See valves.

Sprinkler Heads

Head won’t rotate

Heads that rotate are either a gear rotor or an impact rotor. Gears can break or get debris in the gears. These heads tend to need to be replaced once this condition occurs. Impact heads use water flow to rotate the head. If the water pressure is adequate, these heads can sometimes be fixed by cleaning the inside of the heads.

Spray heads pop up, but no water comes out

Debris in nozzle. Center screw turned in on spray head nozzle. Clean or replace nozzle

Water shoots straight up from head

Rotor heads probably have the top of the head broke off or debris in the seal. Replace head if needed.

Spray heads have a broken or missing nozzle or a possible damaged seal. Flush replace head or nozzle if needed.

Puddling around a head or heads

Causes are: cracked head, broken riser under head, break in the pipe below head, down line drainage or zone valve passing water.

You can flush a seal by holding the head down while the zone runs. This will allow water to flow out the seal and flush it. The nozzle can break on spray heads. They can be replaced by holding up the stem with the water off. Do not drop stem into head without a nozzle on it, or you will have difficulty retrieving the stem. Unscrew the old nozzle and screw on the new nozzle. Make sure you replace the old nozzle with the same spray pattern that was removed.

Sometimes you can dig up the head and find a broker riser or a leak under the head. If so, just replace the fitting.

Sometimes heads will need to be replaced unless you have down line drainage or the zone valve is passing water. Down line drainage should dry up within a couple of hours of running the zone. If the puddle does not dry up it is probably a zone valve passing water. You can test it by turning off the sprinkler main tap (sprinkler turn on valve) for a day and see if the puddle dries up. Or shutting off the valves on the back flow device works too. If the water dries up with water off, the cause is normally a seeping zone valve for that zone.

Debris in valve seals, bad diaphragm, or solenoid can cause seeping and passing of water while in the zone is not running. Clean, rebuild or replace valve. See valves for repair details.

Lawn Discoloration

Brown spots

Partial plug in head nozzles, head not rotating, station run time to short or not frequent enough, Leak in the zone, a head not popping up above the surface, zone not coming on, part of the zone not working, loss of pressure, single coverage or bad installation.

Check that all heads are spraying correctly and that rotor heads are rotating. Make sure all the zones are actually coming on, check run times and frequency on controller, check for a puddle in the zone.

Part of the zone does not work

A tree root can pinch the lateral zone pipe partially or completely. The heads up stream from the pinch will work great. Heads downstream from the pinch will perform badly or not come up at all.

Heads do not pop up

Normally caused by low pressure due to a leak in the zone, also see low pressure on system for repair details.

Leaks in the system

2 types of leaks

Main line leak

The main line pipe goes from the main tap inside to the valves in the valve box and is under pressure 24/7. To depressurize the main line pipe turn off the Sprinkler Main Tap inside and drain. Or you can close the valves on the back flow device by turning them clock wise to the stop or perpendicular to the valve. You can drain the main line pipe by opening a manual drain or by running zone valves for up to 2 minutes. Tends to be ¾ or 1”Copper PVC or PEX in the house to the back flow device, then to ¾ or 1” PVC or poly pipe after the back flow device.


Lateral pipe leak

This pipe goes from the zone valve in the valve box to the heads, and is only under pressure when the zone valve in the valve box is activated. In Colorado lateral pipe is mostly ¾” or 1” poly pipe. This can be repaired with a poly insert. Just insert a new section of pipe with 2 inserts. Do not kink the pipe. Inserts can be wiggled in or tapped in with a rubber mallet. Pinch clamps are the best clamp. Gear clamps rust and cannot be easily removed. Loosen pinch clamps by wiggling a small screw drive in the pinch point of the clamp.

Water never dries up

Indicates a leak in the mainline pipe. Tends to because by a seeping zone valve or break in the pipe.

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Water Pressure problem

Low pressure on a zone or station

Tends to be caused by a leak somewhere between the zone valve and the heads. Other causes are roots pinching the pipes, zone valve not opening completely, too many heads on the zone.

A leak in the lateral pipe will take pressure from the entire zone and make all the heads perform poorly or not at all. Look for puddles in the area the zone waters looking towards the valve box that the zone valve is in. Check around each head as the zone runs for water bubbling up around a particular head. When you find a wet area where water is bubbling up from the ground. Dig up the puddle and follow the water the leak.  You may need to turn the zone off and on as you dig the whole.

If a root has pinched a pipe it can be difficult to find unless the root has broken the pipe and a leak bubbles up from the ground. Look where you think the lateral pipe runs and determine if a tree is close by. The best Way to find the pinch is to listen for water being impinged. I find these problems by sticking a long screw driver in the ground and putting my ear to the screw driver handle while the zone is running. My trained ear can actually hear the water rushing through the pinch.

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Low pressure on the entire system

Tends to be a problem with the main line pipe, somewhere between the Sprinkler Main Tap in the house and the valves in the valve boxes in the ground.

Causes: sprinkler main tap or back flow device valves not fully open, multiple zones turned on manually or electronically at the same time, main line leak, master valve, roots pinching the main line pipe.

Start simple check the sprinkler main turn on and make sure it is fully open. Check the backflow device make sure the valves are fully open. Handles should be parallel to the valve. Then make sure the zone valves are manually turned off in the valve box. Check the zone valve bleeder screws by hand turning them to the right. Also make sure all the solenoids are hand tightened to the right. Look for a puddle between the valve boxes to locate any leaks. Maybe a tree root is pinching the main line pipe. If all else fails you can check the house water pressure.

Zone Valves

Are located in the valves boxes or directly buried in the ground on old systems. The valve is activated when the solenoid receives a 24 volt electrical charge from the sprinkler controller. The solenoid has a copper coil that pulls up a plunger when turned on with a 24 volt signal. When the plunger is lifted up it allows water to flow on top of the diaphragm in the valve body. This creates pressure on the diaphragm and open up the diaphragm, turning on the zone. When the electricity shuts off the plunger goes back down under pressure from a spring. This will stop the water flow through the pilot hole and equalize the pressure on the diaphragm. Then the diaphragm will close with the assistance of a spring. Turning off the zone or station.

There are three ways to activate a zone valve manually. The first, is to use the timer or controller. Second, you can also turn the solenoid on the zone valve to the left about a half turn. Third, Turn the bleeder screw or switch to the left.

Zone Valve Repair

A seeping valve can be caused by debris in the valve, you might able to clean the valve seating surfaces around the diaphragm. A zone valve can be repaired by replacing the top half of the valve with a like valve. Make sure the water is off and depressurize the main line pipe, drain it if you can. Unscrew the top half of the valve in the ground and remove all the guts including the diaphragm. Do not allow water to enter the valve and always keep debris out of the valve and off sealing surfaces in the valve. Install the new guts and top of new valve to the valve in the ground. Do not over tighten. Use water tight wire connections but polarity does not matter with the wires there is no positive or negative wire it doesn’t matter. Just cut the 2 wires that go to the old solenoid and splice in the 2 wires for the new solenoid just like they were originally.

If that does not work replace the valve if needed.

Finding the problem valve

You can determine which valve runs the problem zone by going into the valve box and manually starting that zone buy opening the bleeder screw or rotating the solenoid about a half turn to the left. You might be able to go to the controller and look at the wire colors and find the wire color to the problem zone. Then go to the valve box and look for the solenoid wire with the same color. The wires can be changed when wires are extended with a splice so this does not always work.

The fastest way I find a leaking valve is by logic and sound. We want the valve box that is closest to the zone with the leak.

Then I listen to each valve for water flow in that valve box. I use an old-school mechanics trick. With a long screw driver, I place the screw driver on the valve. Then I put my ear on the screw driver handle at the opposite end of the screw driver. Cover the other ear and listen for water flow. The more water passing the easier it is to hear the water flowing. The valve making the most sound is the one with the leak. You can practice hearing the sound by running a zone and listen to the back flow device or valves with a screw driver. It’s a swooshing sound.

Zone Valve stuck on

Common causes: solenoid is damaged, wore out or manually turned on, bleeder screw not closed, debris inside any of the sealing surfaces, diaphragm inside of the valve is damaged or wore out, diaphragm spring wore out, valve installed backwards.

Start simple make sure the controller is not manually turned on. Make sure the solenoid and bleeder screw are turned off and hand tightened to the right or clockwise. Inspect the inside the solenoid to make sure the plunger and spring are functioning.

You can disassemble and clean the diaphragm sealing surfaces inside the valve, or remove debris to repair the stuck valve. Make sure to inspect all components for damages and debris. You can remove the top half of the valve and all the internal components. Then replace them all with the top half and components from a new valve of the same model. The valve can be removed and a new valve installed. Inspect the valve for cracks.

Solenoid Replacement

Turn off the water and drain manually if possible or run a zone for a couple minutes with the water off to activate the auto drains. Gently unscrew the solenoid. Install a new solenoid of the same model. Cut the 2 old solenoid wires and connect the 2 new solenoid wires just like they were. One wire will be a common wire the other will be the hot wire. The solenoid does not care about the direction of electrical flow. Connect the 2 wires from the new solenoid to the common and hot wire you just cut. It does not matter which wire goes to the common or hot as long as you have a common and a hot wire it will operate.

Replacing a valve

Be careful you can damage the manifold while doing this. If the manifold breaks it will probably have to be replaced causing a much bigger job and expense. Unless it is an easy job, I suggest hiring a professional for this job. Remove all water pressure from the system and drain it. Dig a hole to the lateral pipe without damaging the pipes. I expose at least one foot of lateral pipe downstream from the valve for room to work. The bigger the whole the easier the job. Cut the lateral pipe. Then you can unscrew the pipe you just cut from the valve. Then the valve can be removed and replaced. Pay attention to the direction of flow marked on valve. Use at least 7 wraps of plumbers tape on threads when installing the new valve. Replace the lateral pipe fitting and run a new piece of pipe to where you cut the lateral pipe and couple it together. Cut the wires from the old valve leaving room to connect the new valve wire. One wire will be a common wire the other will be the hot wire. The solenoid does not care about the direction of electrical flow. Connect the 2 wires from the new valve to the common and hot wire you just cut. It does not matter which wire goes to the common or hot as long as you have a common and a hot wire it will operate.

Diaphragm replacement

The method of replacement depends on the valve type. Always shut off the water and drain system manually or by running a zone for a couple minutes with the water off to activate the auto drain.

Jar valves unscrew the outer ring or jar top to disassemble the valve. Gently remove the top of the valve to expose the diaphragm. Keep the removed portion of the valve clean. Place it in a plastic bag or on a clean surface. Replace the diaphragm making sure you keep all surfaces clean. If the diaphragm has a hole in it, make sure to line the hole in the diaphragm up to the pin hole in the valve where the solenoid sits. Reinstall the top of the valve making sure to include the spring. You will need to be very careful to make sure the pin goes into the center of the diaphragm. Hand tighten the top of the valve. If the valve seeps you can gently use a large pair of channel locks to slightly tighten the ring or jar top.

Valves with screws carefully remove all the screws with a long screw driver or drill set on low. Gently remove the top of the valve to expose the diaphragm. Keep the removed portion of the valve clean. Place it in a plastic bag or on a clean surface. Replace the diaphragm making sure you keep all surfaces clean. If the diaphragm has a hole in it, make sure to line the hole in the diaphragm up to the pin hole in the valve where the solenoid sits. Reinstall the top of the valve making sure to include the spring on top of the diaphragm. Gently reinstall the screws the same way you mount a tire. Install the first screw and screw it ¾ in and the install a screw on the opposite side of the valve the same way. Once you have them all ¾ tight, go back to the first screw and screw it in loose. Repeat the process until all screws are just loose. Then with a screw driver hand tighten them in the same manor.  

Slow Closing Valve   

Also known as a lazy valve, sometimes this happens in the early spring and can improve with warmer weather and getting used. Otherwise it can be corrected by rebuilding the valve by replacing the diaphragm, spring and the solenoid, or replacing the valve.

Zone Valve Chatter or pipe hammer

Can be caused by a worn out diaphragm in the zone valve. Rebuild or replace the valve if need be. A hammer arrestor can be installed in the main line pipe to help with water hammer caused by design flaws.

Zones issues

Individual Zone won’t start

Caused by bad a solenoid, bad valve diaphragm, bad wire connection, damaged or cut wire, plug in the valve pin holes, or a controller problem.

Start by manually turning on the valve. Rotate the solenoid to the left a half turn to run the problem valve manually. If the zone comes on consider replacing the solenoid. If the zone does not run you may need to rebuild the top half of the valve or replace the valve if needed.

If the valve runs manually it is likely an electrical problem. To check the controller move the zone wire that is not activating to a station number that is not used or a zone that you know is working. If that runs the zone it is the controller. Otherwise, you can test the valve solenoid with an ohm meter you should get about 24 ohms or just replace the solenoid. Disconnect the solenoid and put a probe to each of the two solenoid wires. Set the tester for continuity and you should get a reading, if you do not get a reading the valve solenoid is faulty. You can test the controller with an ohm meter by activating the station and putting the probe to the common wire screw and the station number screw. You should get around 24 volts.

If the entire sprinkler system won’t start check to make sure the water is on. Inspect wires for being cut. See Controller repair for more solutions.