Acoustic Leak Detection

Pressurised water escaping from a pipe makes noise: a hiss at the orifice, a rumble where the jet hits surrounding soil, a whistle through a crack. Most of it is far below anything a human ear picks up through a metre of ground. Acoustic leak detection is the discipline of amplifying, filtering and interpreting those sounds to put a mark on the ground directly above the leak.

The acoustic toolkit

• Ground microphones: high-sensitivity sensors placed on soil, tarmac or paving in a grid over the suspected run. The leak is loudest directly above itself.
• Listening sticks: direct contact on valves, stop taps and fittings to establish which pipe carries leak noise at all.
• Leak noise correlators: two sensors clamped on the pipe either side of a suspected leak measure how long the leak's sound takes to reach each one. The time difference computes the leak's position along the pipe, even under a driveway.
• Pipe and cable locating: you cannot survey a pipe you cannot find, so we trace and mark the actual pipe route first, not the route on a 40-year-old drawing.

Where acoustics shine, and where they do not

Acoustic methods are at their best on pressurised metal and rigid pipes, where sound travels far and clean: mains supplies, galvanised and copper services, and external stop tap to house runs. They struggle on modern plastic pipe, which absorbs sound, and on very small seeps. That is not a problem for you, because we simply switch to tracer gas when the acoustics go quiet. Every survey carries both.

Quiet, methodical, evidenced

Acoustic work rewards patience. Surveys are done with pumps off and traffic noise minimised, sometimes early in the morning by arrangement. Findings are cross-checked against flow readings and, where possible, a second method before we recommend excavation. The result goes in your written report with the leak position marked on photographs.