A Guide to Locating Plastic Water Pipes Underground

by James Caviness

Generally, there are many different types of pipes that can be found under a home or building; PVC and plastic pipe or plastic water pipe options are becoming more popular due to their strength and flexibility. PVC pipes also do not leach into the water running through them as some metal pipes will. One of the major drawbacks to using PVC is that the lack of any metal makes it a challenge to locate an underground pipe. An underground leak from a PVC pipe can be one of the most challenging types of leaks to locate and can lead to costly repairs over time.

Whether it is water leak detection, underground utilities, or replacing an underground water pipe because of water or water pressure loss, finding these pipes can be a challenge. There are numerous methods and tools that can be used to locate these objects, and one of the most popular ones is using a plastic pipe detector! This method is especially useful when you need to find water pipes for maintenance work or repairs.

Detecting plumbing issues affecting water supply can save money and water by stopping leaks. Plumbing problems can be difficult to find because buried pipes aren't visible. In some cases, homeowners or landscapers will accidentally break a water pipe while safely digging in an area where they think there is no pipe. Hot water heaters and Water meters can also malfunction, which may be due to a buried water pipe that is a leaking pipe.

1. Determine Your Locating Method

Locating a non metallic pipe has been a challenge since they became popular, but the job goes on, and people have found unique ways to locate PVC and plastic pipes while technology took time to catch up. Now that PVC and plastic pipes can be found just about anywhere there are humans and structures, the demand for locating pipes of these materials has become greater - thus, technology has begun to catch up. Two contrasting pipe locating methods show how things have progressed:

Acoustic Pipe Detection

With no advanced technology available to use, it was not uncommon to hear of workers banging on above-ground structures with an ear to the ground, trying to trace PVC lines. Using ground-rods and probes made it easier to detect vibrations from the pipe, and inserting the rods into the ground can manually locate and trace the PVC. Clearly, this was far from precise or accurate, and new solutions were needed.

Using a similar principle, an acoustic PVC detector like Sconstedt's RD-500 allows for precise location and tracing of PVC and non-metallic pipes underground. This type of locator will send a series of electronic pulses and/or mechanical pulses down the length of the PVC pipe. A sensitive ground probe will be used to listen and follow along the length of the PVC pipe. Since this method uses acoustics, the ambient noise level could be a limiting factor; large machinery, roadways, busy streets, and other outside noises can all affect the ability of the operator to hear the signal. The limits of acoustic detection are made up for by more advanced options.

Ground-penetrating Radar

Ground-penetrating Radar will be able to locate PVC and other non-metallic pipes underground with a high degree of accuracy and precision. Ground-penetrating radar does not rely on acoustics, but rather the system will transmit a signal into the ground and measure the speed at which it returns to the receiver; the differences in signal speed are measured, and it is possible to determine the composition of underground targets. While it may be cheaper to bang a hammer on one end of a pipe and listen, Ground-penetrating Radar is used when errors are not an option.

2. Buy or Rent the Necessary Tools

Locating underground PVC pipes requires more skill than locating a metal pipe with a more traditional detector since in most cases, the success in locating a PVC pipe will come down to the skill and listening abilities of the operator, as well as the conditions the detector will be used. Getting the best equipment possible will increase the chance of locating an underground PVC pipe since these options will have more listening options (like different microphones and ground probes), and filters for eliminating background noise. Acoustic PVC detectors are becoming more popular so rentals may be an option, but if this is something that will be used frequently, the cost of rentals may not make sense. Properties or golf courses with significant irrigation may find an acoustic PVC detector a worthwhile investment.

Ground-penetrating radar is more uncommon in the rental world since it requires a bit more training to be able to use it successfully. While renting this equipment may not be as feasible as an acoustic PVC detector, there may be someone in your area who will perform this task for you if you do not have the time to learn or the money to spend on a brand-new GPR system.

3. Map Out Your Property

The more known reference points we have when creating a map, the more accurate that map will be. Filling in the gaps between a known location, like a valve or spigot, and the opposing end of the PVC pipe might be as easy as drawing a straight line. Most town halls will have easy access to the approximate property boundaries of each plot of land in that town. These maps are a terrific place to start, and marking off your property boundaries yourself by locating the survey pins will translate that map from the town hall into reality. Taking it a step further, take a look at your home's building plans to get the exact location where PVC pipes enter or leave your home. The more information we have up-front will make it much easier to find the buried pipe you're looking for.

4. Begin Your Search

With a basic idea as to where the PVC may be located, you can begin by using your acoustic PVC detector to trace the line. With a careful ear, find the location of the loudest response, walk a few feet, and do the same. The more points you trace out, generally, the better, as more points will allow you to visualize where the pipe really is.

When you start digging, dig small holes or even use a probe to disturb the ground and pipe as little as possible. Digging at an angle or using a smaller probe will be the best way to do this without any unintended damage.

5. Re-Bury Pipes with Detectable Tape

As mentioned, metal detectors are generally easier to operate and more commonly available than acoustic PVC detectors. For this reason, we suggest burying your PVC with some type of metallic target to make future location easier. Using metal tape or a tracer wire attached to the PVC pipe will allow you to more easily find the target in the future.

Indoor Plumbing and Material Types

Locating water lines inside may require the use of a stud finder. This tool is designed to locate the studs in a wall. Pipes will typically be laid out based on where the studs are in a wall.

To locate underground water lines, you'll need to know what types of pipe material your pipes are made of. Plumbing pipes come in many different pipe materials, like:

  • Metallic pipes
  • Clay pipe
  • Cast iron pipe
  • Buried plastic pipe
  • Polyethylene pipe
  • Copper pipe
  • PVC piping
  • Iron pipes
  • Buried PVC pipe

Locating Metal Pipes

Finding metal pipes and fittings can be done with a pipe locator metal detector, also called a magnetic pipe locator, and many plumbers and construction companies use this method to find underground metal water pipes. Keep in mind, Buried utilities can be marked or unmarked, but the metal used for smaller pipes is much thinner and more flexible than what you will find in larger water or sewer lines. Locating utility lines can be challenging because of this, but having a metal detector can help.

The most important thing to look for when trying to find a metal pipe is disturbances in the soil that change the magnetic field of the detector's needle. This means that you need to search outside of where your hole will be dug.

Methods for Locating Underground Water Pipes

  • Tracer wire or locator wire: If you're wondering how to find underground plastic pipes, tracer wires are the most common way. They work by attaching the tracer wire to one of your existing lines, such as a sewer or water line, and then walking along your entire property with your metal detector. The tracer wire emits an electric signal that gets stronger when you get close to it.
  • Pipe Locator: Pipe locators are metal detectors that are used specifically to locate water lines, mostly in the construction industry. These metal detectors can be purchased at many major retailers or online. They work by sending vibrations into the ground and listening to the low sounds that bounce back up.
  • Cable locators: Cable locators are metal detectors that look similar to a long antenna that emits a signal into the ground. The operator lowers the device in front of them while walking along, listening for any changes in tone or volume in the sound emitted from the machine.
  • Utility locator: Utility locators are used in construction to find small metal pipes or lines that are not marked, such as water or sewer pipes. Some utility locators work by sending an electrical current down the line and listening for any changes in pitch in the sound coming back up.

Copyright 2021 Detector Electronics Corp. - Revised August 2022