How to Locate Underground Water Lines

Easy access to clean water is one of the foundations of modern society. The transportation of water from city treatment plants to individual residences and businesses is an often overlooked, but critical part of day-to-day life. Beneath our towns, cities, and back yards, a web of interconnected pipelines works daily to deliver the water that we need.

Why You May Want to Locate Underground Water Lines

Like all complex systems, water supply networks require maintenance and occasionally have sections that need to be repaired or replaced. Sometimes other utility maintenance or construction activities need to occur in the same area as an underground water line. In these situations, proper location and identification of water lines is critical to ensuring that they are not damaged and that customers have continued access to water services.

Finding Different Types of Underground Water Lines

Piped water systems have existed since at least the time of the Roman Empire. Pipeline technology has changed drastically over the last two-thousand years and pipeline materials have been updated along with the times.

Some of the most ancient pipeline materials can still be found in use on older water supply systems today, although many are quickly being phased out as cities upgrade their pipelines. These older pipeline material types can include clay, ceramic, brick, lead, cast iron (especially prevalent in the southeastern US), and asbestos. In extremely rare circumstances, wooden pipelines might still be in use and these can easily be over 100 years old.

Despite the occasional presence of older materials, most modern pipeline infrastructure is built of newer piping material such as ductile iron, concrete, or forms of plastic such as CPVC, PVC, ABS, or HDPE. When compared with older material options, modern materials are safe, inexpensive, easy to repair, and easy to replace.

Difficulties in Locating Underground Water Lines

When a new pipeline is installed today, the locations are usually quickly entered into mapping software using highly accurate GIS systems. For water lines installed before the 2010s, however, there is a good chance that any map produced was hand entered onto computer mapping systems or drawn on city plans by with pen or pencil.

For many municipalities, these maps can be notoriously unreliable and many smaller water supply organizations have traditionally relied on the knowledge of senior employees to find pipeline locations. The downside to this is that, as the older generation of water supply managers retire, the knowledge they have of system locations can be lost, leaving new water works employees in the dark when lines have to be repaired or replaced.

Underground Water Line Location Tools

Fortunately, a variety of utility location tools are available to water service professionals. These locators can remove time consuming and expensive guesswork on repair and replacement projects. The type of locator used is dependent on several factors including the material of line being that is being located, the presence or absence of trace wires, and the environment in which a water line is buried.

Traced vs Non-Traced Underground Water Lines

For the purposes of locating underground lines, pipelines materials can be divided into two broad categories: conductive and non-conductive. Conductive lines allow the conduction of electrical signals along the length of a pipeline. Materials for these lines can include ductile iron, cast iron, copper, lead, and brass. Non-conductive pipeline materials include plastic/PVC, ceramic, concrete, and asbestos.

Non-conductive lines can be more difficult to locate, and water supply engineers often install copper trace wires along sections of non-conductive pipelines to help in future locating efforts. The presence or absence of trace wires or conductive pipeline materials will determine which line locating device is most appropriate for the job at hand.

AML / All Material Locators

All Material Locators or “AMLs” are produced with proprietary technology by Subsurface Instruments. An AML works by projecting an ultra-high radio frequency into the ground. When a signal is reflected back to the receiver, it is interpreted by an onboard computer and the operator is alerted to any density change. This technology allows the user to search for any item with a density different than the surrounding environment. This can include both conductive and non-conductive pipelines. These locators are an excellent all-around tool for identifying all types of buried pipelines in areas that are relatively free of other buried materials such as rocks, concrete, and tree roots.

Utility Locators

Utility locators have long been the industry workhorse for finding conductive and traced non-conductive pipelines. Utility locators work by projecting an electromagnetic signal along the length of a pipeline or cable with a transmitter device. A receiver wand is then used to scan the ground along the length of the pipeline and to interpret the signal received from the transmitter.

Utility locator transmitters can create a signal along a line using either conduction or induction.

Conduction involves a direct connection between the transmitter and the pipeline or trace wire. This is usually done with connector cables. A ground stake is also used to complete the circuit. Direct transmitter conduction is usually more powerful than induction and allows the pipeline to be traced at a further distance from the transmitter box.

Induction involves indirect signal transmission. The transmitter box is placed over the pipeline to be traced and emits an electromagnetic signal into the ground near the pipeline. This signal induces an electromagnetic signal in the pipeline or trace wire.

Alternatively, a transmitter clamp can be used to trace a line that may be encased in PVC. Induced signals usually do not travel as far along the pipeline since a large amount of the transmitter wattage is expended in projecting the signal through soil or air.

Utility locators are very accurate and can even provide an estimate of the line depth. However, they are of limited use if the line is non-conductive (plastic/concrete) or if the trace wire has been broken.

If it is believed that a pipeline has a broken trace wire, a ground fault locator such as the A-Frame by Subsurface Instruments can help to locate the trace wire break for repairs.

Sewer Cameras

Sewer cameras, sewer snakes, and trace rods can be used in conjunction with utility locators. If the snake or trace rod is made of a conductive material, the transmitter box of a utility locator can be connected to create a traceable signal inside a non-conductive pipeline. An alternative method is to use the sonde or transmitting head on a sewer camera. These sondes typically transmit at industry standard frequencies and can easily be read by most utility locator receivers.

Magnetic Locators

Magnetic locators can be used to find pipelines if they are made of ferrous materials such as iron and steel. Magnetic locators can also be used if a non-conductive pipeline is equipped with ferrous joints, valves, or hydrants. The magnetic locator is limited in scope since it can only read ferrous components.

Subsurface Instruments produces a combination utility locator / magnetic locator known as the PL-TT. This powerful locator incorporates the advantages of both a magnetic locator and traditional utility locator systems.

Can you Locate Underground Waterlines Yourself

Line strikes and breaks can be dangerous and very expensive. It is always advisable that water and other utility lines are located prior to breaking ground on a project.

Private utility location services are generally provided free of charge through your state’s 811 telephone line. Calling 811 automatically routes you directly to your local 811 center and each state has its own specific locating guidelines. If your state accepts online requests from homeowners and contractors, you may be able to file an “online request”.

If you are a contractor, water service provider, or private citizen, utility location tools can also be useful devices for double checking locations provided by the 811 service. A second reading is never out of place and ensures that all lines have been located properly. Having a utility locator on hand can also be useful in time sensitive projects where an 811 technician may not be able to arrive immediately.

Contact us with Questions about Underground Water Line Locators

If you are deciding on whether to purchase a locator for underground water lines, please feel free to reach out to us at Precision Outdoor Tech. We will discuss your needs and project specifications and will point you in the right direction to a line of products that can help you to locate the water lines on your system. Give us a call with your questions, and we will be happy to help you out. If it is after hours, please use the contact form listed in the municipal contact section directly below and we will respond shortly.

Municipal and Government Customers

We love our municipal and government customers. If you need to request a quote or have alternative payment requirements, please visit our government customers page.

If you have already decided on the type of locator that you would like to use for your project, you can find our product collections via the following links.

All Material Locators (AMLs)

For all pipeline types, including non-conductive materials. All Material Locators work best in non-rocky soils away from tree roots.

Utility Locators

Utility Locators for conductive pipelines or trace-wire equipped non-conductive lines.

Sewer Cameras

Work great for tracing non-conductive pipelines with the help of a utility locator receiver. Sewer cameras can also record videos of pipeline interiors to inspect for damage.

Magnetic Locators

Magnetic Locators are appropriate for steel, iron, or cast-iron pipelines, valves, and pipeline joints. The size of the target determines the depth that at which it can be read.