Updated 2026-10-23
How do you find water for a borehole in granite or hard rock?
In granite and other hard rock, water sits in fractures, so the survey has to locate a water-bearing fracture rather than an aquifer layer. WaterLocation records seismic and resonance signals across the site and gives a drilling point, depth and forecast yield; on a granite hilltop in Bavaria this found 200 m³ a day at 22 m.
Why hard rock is different
Sand and gravel aquifers hold water across a wide area. Solid rock holds it only in cracks and fault zones that may be a few metres wide. A survey that looks for layers sees no aquifer and returns a negative forecast, even when a productive fracture runs nearby.
How a fracture survey works
The method is related to hammer seismic surveying, but in addition to the echo it records the resonant response of the ground. Software interprets both and shows where a fracture runs, how deep it lies and how much water it can give. Field work usually takes 2–3 days.
Hard-rock wells
| Site | Before | Result | Yield |
|---|---|---|---|
| Mitterfirmiansreut, Germany | Granite hilltop, four dry holes | Water at 22 m | 200 m³/day |
| Ulrichstein, Germany | Basalt hills, all boreholes failed | ≈200 m well | 300+ m³/day |
| Altmannstein, Germany | Jurassic limestone, old well gave 2 l/s | Water at 88 m | 864 m³/day (10 l/s) |
| Kalahari, South Africa | Rock and quartz, 4 of 25 wells steady | 150 m borehole, static level 28 m | ≈200 m³/day |
Questions
How deep are hard-rock wells?
Usually less than 200 m. In these projects water came from 22 m to about 200 m.
What rig is needed?
An air-flush rig; if drilling fluid is unavoidable, cellulose-based only.