Can You Locate and Trace a Domestic Water Pipe?

Can you locate and trace a domestic water pipe? Here is the honest answer from our surveying team.

Why domestic water pipes are hard to detect

Most domestic water pipes in the UK are plastic and around 1 inch / 25 mm in diameter. Because they are non metallic and so small, they are very difficult, often impossible to locate with the same techniques we use for bigger mains and other utilities. Electronic locators like CAT and Genny need a conductive pipe or a connected tracer wire to work reliably. Ground Penetrating Radar (GPR) can sometimes see plastic, but small diameter services at typical depths are frequently below the radar’s reliable detection threshold and results depend heavily on soil conditions, moisture and clutter.

In short, instruments that are excellent for mapping larger mains and cables are rarely decisive for a single, small domestic service pipe.

The most reliable way to work out your pipe’s route

Domestic supply pipes usually run in a straight line from the external stop tap in the pavement to the point where they enter your property. The external stop tap is often identifiable by a small cover in the pavement. Inside, you should have a stop tap near this entry point. The straight line between these two taps is normally the pipe route. However, installers sometimes route around obstructions such as trees, walls, driveways or drainage runs, so allow for gentle deviations where needed.

1. Find both stop taps. Mark the straight line between the pavement cover and the internal stop tap location.
2. Look for likely obstructions along that line and adjust your expected route slightly to skirt around them.
3. Confirm the route and depth by carefully hand digging short, narrow trial trenches across the suspected line. Use insulated tools and proceed slowly.
4. Measure the depth where the pipe is exposed, then backfill carefully. If the pipe is not on a straight line, repeat with two or three trial trenches to map the actual route.
5. Record your confirmed line and depths for future reference.

How deep are domestic water pipes?

Depths vary, but as a guide in the UK a water service should be between 750 mm and 1350 mm below ground level to protect against frost. In reality they can be shallower, especially near property entrances, under drives, or where ground levels have changed over time. The only dependable way to know your pipe’s exact depth at a given point is to expose it by careful hand excavation.

Safety and good practice before you dig

• Assume other utilities may be present. Even if the water pipe is hard to trace, use a cable avoidance tool to scan for power and telecoms nearby and review any available utility plans.
• Hand dig with insulated tools and never use power tools directly over the suspected line.
• Wear appropriate PPE and support trenches as needed, especially in soft or made ground.
• If you suspect a leak or find damage, isolate at a stop tap and contact a qualified plumber or your water supplier.
• Backfill with care, protecting the pipe and restoring ground in layers.

When technology can help

While small plastic domestic services are often beyond the reliable limits of instruments, technology is very effective for mapping larger water mains and other utilities, or where tracer wires or access points allow us to induce a signal. Our Underground Services Tracing team combines multiple methods to build a robust picture of buried infrastructure. For a deeper look at how methods complement each other, see our guide on combining Ground Penetrating Radar and radio detection.

If you are planning works, it can be valuable to integrate utilities tracing with a measured site plan. Here is how to combine underground utilities with a topographical survey so that confirmed routes and depths sit accurately on a georeferenced drawing.

Key takeaways

For most homes, the practical approach is to identify both stop taps, assume a straight line between them, account for obvious obstructions, and then verify the route and depth by cautious trial holes. This method is usually faster and more reliable than relying on instruments designed for larger or metallic utilities.

If you need a comprehensive underground services map for a project or you are dealing with more complex utilities, we can help. Request a quote for Underground Services Tracing or explore our service overview here: Underground Services Tracing by Bury Associates.

Not sure what you need? Get in touch with our team for guidance: contact Bury Associates.