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How to Find a Broken Sprinkler Pipe Underground

When it comes to maintaining a healthy, lush green lawn, a sprinkler system is a lifesaver.

However, having a broken sprinkler pipe can rob you of your joy.

Muddy pools can ruin your beautiful landscape. Plus, you can get dry patches on one side because the water can’t get through to all the sprinkler heads.

The most horrifying part of it all is that water leaks will make your water bill obscenely high.

The only solution is to find the broken sprinkler pipe and plug the water leak before the bills get out of hand.

Let’s talk about how to find the exact location of a damaged pipe.

Sprinkler systems
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Locating an Underground Broken Pipe

Tracing the leak is the only way to find the cracked pipe. Here’s how you can follow the leak to get to the damaged pipe. 

Step 1: Trace the Path of the Irrigation Sprinkler Lines

The first step to locate a leak is to understand how the underground irrigation lines in your sprinkler system are laid out.

If you’re lucky, the people who installed your system might have given you a map of the entire system. If you don’t have the irrigation system plan, you will have to do a bit of digging to figure out how the system is laid out.

Thankfully, you don’t have to dig out the whole yard. If you know these basic facts about irrigation system installation, you’ll have an idea of where to start digging: 

  • Irrigation pipes are made up of straight and T-joint pipes. This means that if you find one, the next pipe should be straight ahead or to the left or right at a 90 degree angle.
  • The sprinkler pipes are buried about 8–12 inches into the ground. Because you won’t find the pipes buried too deep in the ground, there’s no reason to keep digging in one spot if you don’t see anything within the 12 inch range. 
  • Most irrigation system pipes are made of PVC (older systems had metal pipes), so you can use pipe detectors to pinpoint their location.

To locate the first pipe, dig near the valve boxes and areas close to the sprinkler heads. Once you unearth the first pipe, keep mapping your system. Use tape or spray paint to mark the rest of the pipe layout.

You can dig again after 2–3 feet to confirm you are in the right direction.

Tip: Dig very carefully and hold your shovel at an angle to the ground (don’t hit straight down) to avoid hitting the pipes.

Step 2: Isolate the Source of the Leak

Now that you know the layout of the pipes, it’s time to single out the area where the underground leak is coming from. You can either dig or use more sophisticated sound detecting tools.

Find it by Digging

Each zone on the sprinkler system is connected to the water supply separately. To identify the area where leaks happen, you will need to shut off water to the irrigation system to let the ground dry up. 

  1. Turn off all water supply to the sprinkler system.
  2. If your system is connected to a sprinkler controller, you can set it to rain mode or shut it off for a few days. Turning off the irrigation controllers stops the electrical clock so be sure to reset the timer once you’re done.
  3. Wait for a few days until the ground is completely dry. How long this takes will depend on the weather. 
  4. Once the ground is completely dry, cover all the sprinkler heads with caps.
  5. Open one zone at a time and inspect the ground above each marked area (the ones you spray painted before) to see if there are any wet pools or if the lawn feels elevated. 
  6. Once you identify any wet areas, shut off the water and dig in those places to expose the pipes. 
  7. Now, open the water once again. You will see a gush of water or small bubbles on the line with the leak, depending on how big the crack on the pipe is. 

Following the Sounds

Water meter reading noise tool
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You can also isolate a leak if you pay attention to the sounds of water flowing through the pipes. This requires specialized equipment like:

  • Leak noise locators
  • Leak noise correlators
  • Acoustic testing kit with water leak microphone and headset

Use these specialized tools to listen for the sound of an underground leak along the irrigation lines. Follow the spray-painted areas that you marked out before.

How do sound tools work?

The science behind noise detecting and acoustic tools is based on soundwaves. The devices are designed with a highly sensitive transducer (that’s the part that can “hear” the sound waves).

They can detect the difference in the sound of the water flow inside a pressurized sprinkler pipe. Much like how you can hear a hissing sound when the watering hose is broken.

These tools can pick up on the disruption in the normal flow of water even when the soil covers the pipes.

Leak noise correlators are the most sensitive. They can pinpoint the exact location of a leak by using algorithms to calculate the distances it takes to get from the sensors to the leaking pipe.

Using noise detecting tools makes locating damaged pipes an easy one-person task. It’s faster, and there’s less digging involved.

However, the catch is that these specialized devices for pinpointing underground pipe leaks are usually highly technical, and you will have to do some research to understand the readings.

Once you’ve pinpointed the leak, dig to expose the pipe and confirm the position of the damage.

Watch this video for a detailed guide.

Note: Whichever option you choose to locate the leak, you should know that leaks can be tricky. The position where you see the water leak is not always the exact place where the pipe is broken.

You will have to inspect the pipe several inches on either side of the point where you spotted the leak to locate the cracked pipe.

How to Repair a Broken Underground Pipe

Once you’ve located the pipe, it’s no good to leave it like that. You have to take care of it quickly. Apart from the obvious water bill situation, underground leaks can cause a lot more water-related damage to your house. For instance:

  • The water may seep into and weaken your home’s foundation, decks, patio, and any other nearby structures.
  • A steady leak can ruin utility lines. 
  • If the leakage is excessive it may cause underground cavities and sinkholes.

Here’s how you can repair the pipe before the leak wreaks havoc on your home:

  1. Carefully dig at least 1 on foot deep and 1 foot wide to fully expose the pipe to prevent any dirt from entering the irrigation system while you work. 
  2. Measure the broken pipe and cut out a new length of piping of the same length
  3. Cut off the length of the broken pipe from the irrigation system about 4–10 inches long depending on the extent of the leak. 
  4. Put in a new length of PVC pipe and attach it using couplers on either side. Use pipe cement and PVC primer to keep the joint in place.

    Good luck
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  5. Leave it to dry for 24 hours to dry completely.

    You guys have no loose wiring
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  6. Now turn on the water at low pressure initially. Gradually increase water pressure and see if the joint holds out. If there’s no leaking, cover the hole.

And that’s it, your cracked pipe and water leaking problem is sorted. 

Tip: Cut out the lawn on the parts you want to repair into small square patches making sure not to disturb the roots. Ensure to carefully lift the grass patches with the soil and roots intact.

Once you’re done, you can simply replace the patch of grass, and it will grow right back as if nothing happened.

Proper Maintenance of Your Sprinkler System

Valve body
Sprinkler Valves

Your sprinkler system is an investment worth protecting. Once you’ve handled the problem with the pipe and fixed the leak, seize the opportunity to check for any other issues with your system and replace any worn parts.

Take a look at the sprinkler heads to rule out any leaking heads. You can do this by putting a cap on each sprinkler head and turning the sprinkler stations on. If the sprinkler heads are working well, the cap prevents water from coming out.

If you notice any water leaking out, you may need to readjust or change the leaking sprinkler head.

You should also check if the sprinkler valve system works the way it should. Close the valve box and open the main water supply to release water into the irrigation system.

If the valves are leaking, you will notice some water coming out of the closed valves, and you’ll need to replace the valves with a new set.

If you need any help figuring out the best replacement parts like your sprinkler valves, irrigation controller,  and other sprinkler system parts, turn to the Sprinkler Supply Store. We are happy to help you figure out how to keep your system in tip-top shape.

"Absolutely one of the best in the business! The sales staff has come through for me on multiple occasions with advice on replacement parts and technical information on the operation of my sprinkler system." — Peter Staire

Contact the Sprinkler Supply Store today for all your sprinkler part needs.

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