How to Troubleshoot Your Lawn Irrigation System

The first step in troubleshooting a lawn sprinkler system is to carefully observe the problem and identify which part is malfunctioning. Next, refer to the manufacturer's website or manual for specific instructions on the repair or replacement of the problem unit.

General solutions to the most common problems are outlined here, but if you need more information to fix the system, it's always best to check manufacturer guidance.

If Individual Sprinkler Heads Aren't Working

One of the most common problems with a lawn irrigation system is when sprinkler heads get damaged, which is usually easy to spot. Damage to sprinkler heads is common if the heads are set too high and are run over by lawnmowers or cars.

1. Find the Issue

   First, confirm if a broken sprinkler head is the problem. Look for:

   • Damage to the plastic casing on the sprinkler heads
   • Sprinkler heads that don’t pop up
   • Water that sprays wildly or not at all
   • Sprinklers with heads that are completely broken off

2. Clear the Sprinkler Head

   Once you find the damaged head, clean it of debris and reset its spray pattern. Keep an eye out during the next cycle to see if the spray head performs correctly or needs to be replaced.

3. Replace the Sprinkler Head (If Needed)

   If the head still isn't working after a clean and reset, replace it. This can typically be done by simply unscrewing the sprinkler head from the riser tube, then screwing a new one on.

If the Sprinklers Are Producing Low Water Pressure

This problem shows itself through sprinkler heads that barely spray water— or sometimes, the heads won't even pop up. There are several possible causes and solutions.

1. Check the Backflow Device

   The backflow device is normally located above ground where the main water pipe descends to the valve box. To determine if it's malfunctioning, start by ensuring the water valves at the backflow device are fully turned on.

2. Look for Water Pipe Leaks

   A more serious cause of low water pressure is a water pipe leak somewhere along one of the underground irrigation lines. If this is the culprit, you may find areas of soggy lawn where water is pooling or gurgling up. This shows where you need to dig down and repair the water line.

3. Find Issues in the Irrigation Line

   If you can't find an obvious leak, the irrigation line may be crushed or compressed by tree roots or a vehicle, restricting water flow. The only option here is to systematically dig up the lawn until you find the bad pipe and replace it.

If Sprinkler Zones Do Not Turn On

If a sprinkler zone doesn't turn on at all it's usually a problem with the electrical signals running from the controller to the valve solenoids. Sometimes—but more rarely—this can be caused by a faulty valve that needs to be rebuilt or replaced.

If Only a Single Zone Is Inactive

1. Check the Voltage

   The problem may be insufficient voltage to the terminals feeding the wires leading to one of the valves. Use a multimeter to test between the common terminal and zone terminal—if the voltage is too low (anything under 24 volts) you will need to replace the entire controller.

2. Consider the Low-Voltage Wires

   The low-voltage wires leading from the controller to the zone valve's solenoid may be damaged or disconnected. Check the wires to make sure they are intact and properly connected to both the controller and the zone valve solenoid.

3. Inspect the Valve Solenoid

   The solenoid on the valve may be faulty and need replacing. With the controller in the OFF position, remove the wires on the solenoid and unscrew it from the valve. Screw on a new solenoid, and reconnect the wires.

4. Check the Sprinkler Valve

   The valve itself may need to be cleaned or replaced. In some cases, simply disassembling and cleaning the diaphragm will solve the problem. In other cases, replacing the diaphragm and spring will be the fix. In more severe cases, replacing the entire valve will be the solution.

If Multiple Zones Are Inactive

1. Test the Transformer

   The problem may be with the transformer supplying power to the controller. Use a multimeter to test the wire terminals marked "24-vac." If the reading is below 22 volts, replace the transformer.

If There Is Leaking Around the Zone Valve

Leaking around a zone valve could be caused by several issues.

1. Tighten Screws

   On valves where the anti-siphon device is built into the valve, you may need to simply tighten the screws holding the cover to the body of the valve.

2. Install a New Diaphragm

   Leaking can also be caused by a torn or damaged diaphragm inside the valve. In this case, disassemble and rebuild the valve with a new diaphragm.

3. Check the Zone Valve

   A cracked valve body could be the cause leaking. In this circumstance, call a professional to help replace the zone valve.

If There's a Leak at the Sprinkler Head Farthest From the Zone Valve

When there is standing water or leaking water at the sprinkler furthest from the sprinkler zone valves, there are a few possible causes.

1. Check the Sprinkler Head

   The leaking could be caused by a dirty or damaged sprinkler head that needs to be cleaned or replaced. Inspect the head and correct any problems you find.

2. Rebuild the Zone Valve

   A worn-out or damaged zone valve can also cause this issue. It may be a sign that the valve is failing to close completely. Dissemble, clean, and rebuild the valve. If this does not solve the problem, the valve may need to be replaced.

3. Look at the Flow Direction of the Valve

   A valve that is installed backward may also cause this problem. Check the valve to make sure the flow direction is correct.

When to Call a Professional

A DIYer with an understanding of the components and some plumbing or electrical experience can fix many common issues with an irrigation system. However, there are some instances where it's safer to call a pro.

Since sprinkler systems involve both electricity and water, there can be a risk of shock when trying to fix or replace valves and wiring. If you discover a severed wire between the controller and a solenoid or a cracked valve that needs replacing, it's best to seek help from an irrigation system specialist.