You find a leak in an underground water pipe by first checking for unexplained flow at the water meter, then using specialist equipment to pinpoint the source. Surface signs can narrow the search, but they are not reliable enough to determine where to excavate.
Check the water meter
A meter test can confirm unexplained water use downstream of the meter, but not whether the leak is underground. If the suspected loss may instead be inside the building, see how plumbers find hidden leaks behind walls or floors.
- Turn off all taps, irrigation and water-using appliances. Check that toilets are not refilling, but leave the meter supply on.
- Photograph or record the complete meter reading.
- Use no water for at least 10 minutes, then check the meter again.
- If the reading or low-flow indicator has moved, check again for dripping taps, running toilets, automatic irrigation and appliances.
Continued movement indicates water use or loss somewhere on the property side of the meter. The source could be inside the building, underground or at a connected fixture.
Do not dismantle the meter or plumbing. If water is escaping rapidly, avoid flooded areas and electrical hazards. Turn off the property’s normal isolation valve only if it is safely accessible and you know how to operate it. Otherwise, seek urgent assistance.
Look for surface clues
Persistent wet or soft ground, pooling during dry weather, unexplained runoff or an unusually green patch may indicate the general leak area. Water can travel through soil or along a service trench, so it may surface well away from the damaged pipe.
Low pressure across several outlets may support suspicion of substantial water loss. Low pressure at one tap or shower is more likely to be a local fixture problem.
Do not probe or excavate. Concealed electricity, gas, communications and water services may be present, and plans alone cannot confirm their exact on-site positions.
How specialists pinpoint the leak
A plumber or leak-detection specialist identifies the likely pipe route and chooses equipment suited to the pipe and site. Common tools include:
- Pipe locator: Traces the service alignment. Finding the pipe route and locating its leak are separate tasks.
- Acoustic detector: Listens for vibration from pressurised water escaping through a defect.
- Ground microphone: Compares leak noise at different points across soil, paving or concrete.
- Leak noise correlator: Uses sensors at two accessible points to calculate the likely leak position from sound timing and pipe data.
- Tracer gas equipment: A specialist introduces a detectable, non-flammable test gas into an isolated pipe, then scans for gas reaching the surface. This can help when acoustic results are weak.
Pipe material, depth, pressure, ground conditions, thick slabs, traffic noise and access can affect accuracy. Specialists may combine methods before recommending targeted excavation. Once the fault is located, the guide to underground leak repair quote factors explains why a generic price is unreliable.
If the meter continues moving with all water use off and you cannot find the source, contact Fixed Today for professional underground leak detection. Our licensed plumbers can locate the fault, explain the evidence and recommend targeted repair without guesswork excavation.