Irrigation System Won’t Turn Off: Here’s What to Do


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Approximately 30 percent of the water a household uses is for outdoor purposes. That number is even higher in dry regions. If your irrigation system won’t turn off, then not only are you raising that percentage, your bill will also go up, and you take the risk of damaging your lawn.

If your irrigation system does not turn off, you need to isolate the problem. This starts by checking the main water line and the controller. If those are working, then you need to locate the valves and check to see whether they are dirty, the diaphragm is torn, or the solenoid is broken.

No one wants to waste water or have a surprise on the next water bill.  This guide will guide you through the troubleshooting steps so that you can have your irrigation system watering your lawn on your schedule.  

How an Irrigation System Works

The sprinkler heads are the most visible sign of a sprinkler system—besides the green grass, that is. However, there’s a lot under the ground that you do not see. Unless you installed the system yourself or stood watching while it was installed, you might not be aware of all the components.

  • Main and Zone Lines. These are the pipes used to take water through the system. Zone lines run from the main lines to send water to individual zones. The advantage of using this system, instead of having one primary line, is that zones can be isolated to determine where there could be leaks in pipes. 
  • Controller. Commands for valves in each zone to turn on and off come from the controller. Programming water schedules for the entire system or individual zones is done through a controller.
  • Shutoff Valve and Backflow Preventer. In case the entire system needs to be shut down, you need to have access to the valve that will control the system’s water supply. A system also needs a way to prevent water from flowing back into the water supply. Over time, dirt gets into the irrigation pipes, and that dirty water should not be reintroduced into municipal water.
  • Valves and Heads. The heads are what you see on the surface. The valves control the flow of water. Malfunctioning valves are often to blame for an irrigation system not turning off.

Each of these components plays a vital role in a properly functioning irrigation system, and we will explain how to troubleshoot

Check the Main Water Supply

It’s always good to make sure that the problem isn’t with your main water supply valve. If you shut off the valve, and the sprinkler has not stopped, then there is a problem with the valve. Dirt might have gotten into it, it isn’t closing completely, or it is broken.  

If the water stops, then you can move on to the controller. If it does not, you might have other problems, but you need to get that main water supply valve fixed.  

Check the Controller

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Let’s assume that after you tested the main water supply that it worked properly. Now it’s time to check the controller.  

The Display Is Blank

If the display is blank, then in all likelihood, your controller experienced a power outage and went offline. If that’s the case, find the controller’s reset button. It’s most likely the kind of inverter button that requires something thin, like a paper clip end. Once you get your paper clip into the reset slot, press down until you see that the controller is online.

However, do not assume that a working display means your controller is getting power. Controllers typically have a battery back-up, so there may be enough juice in the battery to keep the display going. Take out the battery and see what happens.  

Let’s assume the display remained lit. That means the controller is getting power.   

Other Controller Checks

While you are at the controller, you might as well check a few other things. First, ensure that your controller is set to either run or auto. Remember that if you set watering times, they won’t work until you set the controller to auto.

Also, look at the watering times. You might have forgotten to set them, so if you do not see watering times, you need to set them. While doing this, confirm that the settings are correct for the date, time, and watering days. 

Checking the Transformer on Your Controller

On rare occasions, a controller malfunctions because it is not getting enough power. You need to test for that and make sure the transformer is working correctly. To do this, you will need a multimeter, such as the Mestek Digital Clamp Multimeter (link to Amazon).  

If incoming voltage is 110-120 volts and the transformer is putting out somewhere between 19-30 volts, move on to the terminal strip and valves. If each valve has a reading between 19-30 volts, then your controller is not the problem.  

If those readings are off, you need to decide whether it is time to replace the controller or get an electrician to come out. That’s because you’re going to be testing ohms, disconnecting field wires, terminal strips, and more. Unless you are well versed in electricity, you may decide it’s not worth any more of your time. 

How to Replace a Controller

If you determine the controller is the problem, then it is time to replace it. Maybe you have been thinking of upgrading to a smart sprinkler controller, then check here (link to Amazon) for some options. Not only will you be able to control the sprinkler from your phone, but many smart controllers will adjust watering based on the weather.

When choosing a controller, pick one that has wiring for at least as many zones as you currently have. If you think you might want to add a zone at some point, go ahead and buy a controller with an extra slot.

If you like the settings you have, then make a note of them.

  1. Either unplug the controller or turn off power at the breaker box. It’s essential that there will be no electricity going into the controller. 
  2. As you disconnect the field wires, label them. The wire labeled C or common is the one that carries the power to the controller. If your system does not have a pressure tank, look for PS or MV, which starts the pump.
  3. Each zone will have a set of wires. Either write them down or snap a picture on your phone.
  4. After all wires have been removed, it’s time to remove the old controller and attach the new one.
  5. After you reconnect the wires, plug in or turn on the controller at the breaker box.
  6. Check that each zone comes on.

Hopefully, that will have solved the problem, and water will turn off correctly. If not, then you need to move on to the valves and heads. 

Pro Reminder: Replacing a controller is not complicated unless you forget to label wires, so make sure you keep up with the location and purpose of the wires.  

Fix the Irrigation Valve

How Do Valves Work?

For a sprinkler valve to work, it needs to register that a signal is being sent for it. The solenoid receives the current from the controller telling the valve to open.  

  • When the solenoid receives the signal, it opens the diaphragm, which lets the water out. You can easily spot the solenoid—it’s the part of the valve that has wires attached to it.
  • The housing attached to the solenoid holds the diaphragm. The diaphragm works in conjunction with the solenoid to let water out.  
  • Typically there is a flow control knob or handle that lets you set how much water you want coming out. On most sprinkler valves, the flow control cannot be turned off completely.  
  • Many valves also have a bleeder, which you can use to try and flush out the valves. Sometimes a bleeder will flush out the debris, but not always.
  • A valve also has an anti-siphon device. That is the part that keeps water from going back into the system.   

If you are interested in a more detailed explanation of how an irrigation valve works, check out this fascinating video:

Finding the Valves

Sprinkler valves can be above ground, which makes them easy to spot. They are more typically covered by a valve box that holds the lid in place. Sometimes they were buried in the ground. Finding them can be difficult. Here are several tips:

  • Look for a rectangular top. If you open it up, you should see a series of irrigation valves. Sometimes the lid gets covered by dirt or grass. You can poke around the area where you think the valves could be, but if you are not sure there’s a lid over the valves, this is not recommended.
  • If you do not find a lid, your valves will be buried underground, which will make finding them more difficult.
  • Hopefully, your irrigation system was permitted, so you can call the city or county permitting office for the irrigation blueprint. If you know the company that installed the system, they should also have a plan.
  • Typically the sprinklers nearest to the valve are the first to pressurize, so turn the system on and off.
  • If you can find a wire locator (wire tracer) to rent, use this option. Tracers used by electricians are not powerful enough to sense a signal two feet under the ground (which is how deep the irrigation wires should be buried).  

Pro Tip: The box is dug into the ground so that it is level with the dirt. If the ground shifts over time—as the soil will do—the edge of the box might have shifted so you cannot access one of the valves. In that case, you will have to pull the valve box out. This could require a shovel as the lip on the bottom of the box might be caught on dirt. 

Troubleshooting the Valves

Once you have access to the valves, you can begin troubleshooting. Your first step is going to be determining which valve is causing the problem.  

This is going to be easy if you know which valve controls the sprinkler that will not shut off. If that’s the case, you can move on and make repairs to that valve.

If not, you need to figure out who the troublemaker is.

Identify Which Valve Needs to Be Repaired

If you do not know which valve controls the problem sprinkler, then you need to identify it.

  • Lightly tap the side of the valve several times. What you want to hear is a rattling noise. This means that plastic is hitting plastic, and you can eliminate that valve.
  • Continue tapping on the valves. If you don’t hear the rattling noise, it means that you have water inside the valve. You have likely found the culprit.

Once you have identified the problem valve, double-check that it is turned off, and get ready to take it apart. If you cannot determine which valve is the problem, then, unfortunately, you are going to have to check each of them.

Identify What Kind of Valve You Have

You need to know the brand of the valve. You will either replace it or replace individual parts. Most valves will have the manufacturer’s name stamped on them. In most cases, you will have one made by Orbit, Hunter, Rain Bird, Toro, or K-Rain.   

If you cannot find a model number, you are going to have to do some research. Replacing an entire valve is difficult, and you might need to call a plumber for that.

Repairing the Valve

Now comes the time to inspect the valve. 

Carefully unscrew the lid of the valve. Make sure you note and keep up with all the parts to put it back together correctly. Location is not the only important thing. Pieces like the diaphragm also must be placed in the correct direction. Take a few pictures with your phone if you need to.

  • Dirt. If you see dirt or pebbles in the valve, then you need to clean it out. Dirt or a tiny pebble can keep the solenoid or diaphragm from functioning correctly. Clean out the dirt carefully.
  • Flush. Do not assume there is no dirt just because you don’t see any.  
  • Diaphragm. Inspect the diaphragm. If it has any holes or cracks, you will need to replace it.
  • Solenoid. The wiring around the solenoid should be intact. If your system is otherwise working correctly, you should not be having an issue with the electricity. Turn the solenoid over and make sure there isn’t a piece of dirt inside it. Check that the button inside the solenoid moves freely.

Once you have identified the broken part, you can replace it, put the valve together again, and test the system to see if the problem has been fixed.

What to Do if Your Yard Is Flooded

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Should a valve burst and flood your yard, you might have a problem with the pressure regulator valve (PRV) to your house. The purpose of this is to control the pressure coming into the house from the water company.  

Water pressure in a city needs to be high enough that fire hydrants work properly. Your city’s water pressure might be as high as 200 psi, and the appliances in your house are designed for much lower pressure, typically around 50-60 psi.

Some PRVs have a meter—if yours does, it’s easy enough to check the pressure. You can also rent or buy a water pressure meter and check the pressure that way. If it is too high, then you will need to have the PRV replaced.

Sprinkler Head Problem After Winterizing

Should the irrigation system not turn off the first time you start your system, you could have trapped air. If so, your valves will not function properly.

Air can get trapped in the valve’s tiny pores, thereby stopping the flow of water through the port. Without an adequate flow of water, the valve diaphragm stays open, causing the water to flow.

To fix this, follow these steps:

  1. Turn the main water supply on.
  2. At each valve, you want to get the air bubble to come out, so locate the manual control, which will be either a screw-on top of the valve or a lever on the valve.
  3. If it’s a screw, you want to loosen it enough for water to come squirting out.
  4. After a few seconds, set the screw to the closed position.
  5. Wait a minute to see if the valve closes.  
  6. If it doesn’t, then you will need to repeat the procedure.   

Bottom Line

If the water on your irrigation system will not turn off, the problem is usually with the valves. However, you might also need to troubleshoot other parts of the system, including the controller. Replacing the components inside a valve is not difficult for a DIYer, but if you must replace the entire valve, you might want to call up an expert.

Lars

I am always happy to share all my knowledge about how to keep your garden in good condition and make it special.

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