How to Detect Utility Lines

How to Detect Utility Lines

Locating underground utility lines before digging is highly important. Running into a utility line at a job site can lead to project delays, loss of services, and even injuries and deaths.

Luckily, your company doesn’t have to do any guesswork. There are plenty of methods that you can use to detect utility lines. This article will go over these methods and also give you some extra knowledge.

Even if you know about some methods for detecting utility lines, read on. You’ll probably learn a lot of things that you didn’t know.

Methods for Detecting Utility Lines

Keep in mind that some services are more accurate than others. Also, some services may be too costly for your company to pull off. Try to research the pros and cons of different services before deciding which one is best for your company.


Dowsing is probably the most low-tech method of detecting utility lines. All that you need is a forked stick from a tree. It should be under 20 inches but above ten inches long.

You can then walk around looking for water. Your forked stick should start to bend down when you get close to water. You won’t know the depth of the utility lines, but gentle digging can help you find lines without any issues.

Keep in mind that science hasn’t proven the technique to be effective or ineffective yet. But many expert dowsers will insist that dowsing works. Humans have also used the technique for the bulk of human history.

So it may be a good backup plan if you find yourself in need of low-tech options. But don’t rely on it too much. Also, it only works on water lines.

Ground Penetrating Radar (GPR)

Ground penetrating radar (also known as GPR) uses high-frequency pulses. A utility line detector will send radio waves into the ground. The utilities will then deflect the radio waves back up, and the equipment will display the objects.

It’s great for locating tanks, cables, and other objects. Unfortunately, it’s not the easiest method to use. People have to undergo extensive training to run GPR equipment.

There are also plenty of downsides to using this technology as well. Some soils are difficult for GPR to penetrate. In situations with crowded utilities, it can be difficult to separate one utility line from another.

You can also use such locating technology with horizontal directional drilling technologies. If you’re interested in this technology, learn more at

Electromagnetic Utility Locating (EUL)

Electromagnetic utility locating is perhaps the most common method for locating private utilities. The utility line locator generates an electromagnetic radio frequency. It then detects the conductive materials on some kinds of subsurface utilities.

This technique can do an excellent job of detecting most lines. Such lines include gas, storm, sewer, cable, and many more lines. However, EUL cannot locate unmarked plastic, concrete, asbestos, terra-cotta, or non-ductile pipes.

Also, this technology doesn’t work well if the lines are below a certain depth. Luckily, the answer to the question “How deep are utility lines?” can vary.

Consider the type of utility lines that you’re looking for and if EUL can detect them. If they’re closer to 20 feet deep or more, consider using a different type of detection technique.

Hydro Vacuum Excavation

Unlike the other two methods above, hydro vacuum excavation methods don’t use any form of electrical pulses. They instead use air or water to pull away the soil. By doing this, workers can get a good look at the utility lines without resorting to harsh digging.

For vacuum excavation, equipment users will use high-pressure air. This will break up the soil. The workers will then vacuum up the soil into a tank.

Hydro excavation is pretty much the same. The only difference is that users use water instead of air to break up the soil. Experts also call this technique potholing, hydro-trenching, hydro-digging, or soft digging.

This technique is perfect for difficult soil conditions.

Tips For Avoiding Utility Lines When Digging

Once you’ve detected the utility lines, you still need to avoid them while you’re digging. Consider trying the following techniques:

Don’t Trust Utility Line Markings

You may want to rely on utility lines instead of a utility line detector. However, utility line markings aren’t always accurate. The ground can shift over time and make the utility markings inaccurate.

Use the Right Shovel

Shovels with sharp edges are more likely to cut into utility lines. Don’t use this type of shovel if you know you’re working around utility lines. Get a rounded or blunt-edged shovel instead.

Dig to the Side

Don’t start digging right on top of the utility line. Start digging to the side of it. You can then locate the utility line as you approach it from the side.

Don’t Pry Around a Utility Line

Everything’s not over when you find the utility line. You can still end up damaging the line. Avoid prying around a utility line to remove soil, as this could cause damage.

Take Notes and Make Marks

Once you detect utility lines, make sure that you note their depth. Then keep these notes in a safe place and refer to them while you’re working on your project. It may be a good idea for you to have several copies of these notes.

Also, make sure to make the proper color markings on the ground. The color code system for utilities usually looks like the following:

  • Blue: potable water
  • Yellow: gas, oil, and/or steam
  • Green: sewer
  • Red: electric
  • Orange: alarms and communications
  • Pure: irrigation and reclaimed water

More Interesting Information Ahead

Yes, it can be annoying to have to do all this work to find utility lines. But remember that utility lines provide us with the resources we need in everyday life. It’s important to treat them with the respect they deserve.

Also, are you looking for weird, random, or OMG facts? If so, check out the rest of our site. You’re sure to impress your friends, family, etc., with all sorts of cool information. 

About Saif Jan

A great passionate about learning new things, Blogger and An SEO consultant. Contact me at [email protected]

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