Locating underground water pipes

Underground water pipes can be hard to find. If you have a leak, you will need to find your buried pipes fast. If you want to undertake excavations or landscaping, you will need to know where your underground water pipes are so that you do not damage them. You may want to find your buried water pipes so that you can add an extra tap or undertake renovations.

Dial Before You Dig plans will show the location of the utility’s water mains and water inlet service up to the water meter. However, they do not show the location of privately owned water pipes.

I have been in this industry since 1985. Rarely will you find marker tape indicating that there is a buried water pipe below. However, if you come across marker tape while excavating, stop excavating immediately. Marker tape generally indicates that you are digging directly above a critical buried service. You must either expose the underground service by shovel or hydrovac, or move your excavation.

In most Australian states, house plans for single dwellings do not show the location of water pipes. Site plans for multi dwelling developments will show the location of common water pipes.

Underground metal water pipes are the easiest to locate. Copper water pipes and galvanised steel water pipes are conductive. A metal detector in the hands of an experienced operator is all you need. If you do not have a metal detector you could try using a sharp spike to test the hardness of the soil in the vicinity of the water pipe trench. When you find a number of soft spots running in a straight line, it is likely that you are spiking the line of the trench that the water pipe is buried in. This method can be more miss than hit. We prefer to induce an electronic signal into the copper pipes and galvanised steel pipes and then use a locating device with an inbuilt receiver to find that signal. This method is very accurate and allows us to determine the depth of the underground water pipe.

Underground plastic water pipes with a metal tracer wire can be found using the same methods used for finding underground metal pipes. However, we would not recommend the spike method as you could easily pierce the wall of the plastic pipe.

Underground plastic water pipes without a metal tracer wire are extremely difficult to find. The ability to find these pipes takes years or experience and intuition. It is possible to locate buried plastic water pipes with an internal diameter greater than 25mm by using a small CCTV camera with a locating sonde attached, or using a locating sonde on the end of a push rod. Smaller diameter plastic pipes can be located by inserting a tracer wire into the pipe and using a metal detector. It is also possible to induce an electronic signal into the internal tracer wire, then use a locator device with an inbuilt receiver to find that signal. We use this method as it is the most accurate and will provide the approximate depth. These methods require access to a pipe end and can only be done in lengths of pipe with no tight bends or Ts.

A Thermal camera can sometimes be useful when trying to find underground hot water pipes and some cold water pipes. This method is not very accurate and depends on specific climatic conditions.