Updated 2026-10-23
How much water can a borehole in hard rock give?
A hard-rock borehole that hits a productive water-bearing fracture can give hundreds of cubic metres a day; one that misses it may give almost nothing. In WaterLocation projects, wells in granite, basalt, limestone and dolomite gave 200 to 864 m³ a day, for example 300+ m³ a day from basalt in Ulrichstein and 10 litres a second from limestone in Altmannstein.
Yields by rock type
| Site | Before | Result | Yield |
|---|---|---|---|
| Granite, Bavaria | Four dry holes | Water at 22 m | 200 m³/day |
| Basalt, Ulrichstein | All boreholes failed | ≈200 m well | 300+ m³/day |
| Limestone, Altmannstein | Old well 2 l/s | Water at 88 m | 864 m³/day |
| Dolomite, Namibia | One steady well of nine | Water at 21 m | 350+ m³/day |
Why the spread is so wide
Yield depends on whether the borehole intersects an open, water-bearing fracture and how far that fracture extends. Siting the hole on the fracture is what separates a 200 m³-a-day well from a dry one a few metres away.
Questions
How is yield measured?
With a pumping test after the water-bearing zone is reached.
Can yield be increased later?
A second well sited on another fracture is the usual route; the survey can identify more than one point.