This article originally appeared in The Skeptic, Volume 3, Issue 3, from 1989.
Water divining, or dowsing, is the locating of underground water by individuals who walk over the search area, usually holding a forked stick in a particular way. In areas of low rainfall, water diviners can make a good living by telling people where to dig. There is no question that digging in these spots often produces a viable well.
To ask whether water divining works is an over-simplified question. What is at issue is the mechanism. Diviners often talk of underground aquifers and water courses. Except in limestone areas, this is nonsense. Rock below a certain level, called the water table, is saturated. Above it the rock is not saturated. If you dig to below the water table, anywhere, you will have a well. Depending on the porosity of the rock, the well fills quickly or slowly.
With practice, it is possible to learn where to sink a well for best results. In low-lying ground between extensive higher areas, called an artesian basin, the water table is nearer the surface. These areas can be found from contour maps alone. There are other more subtle pointers, such as vegetation patterns, which might be learned, consciously or unconsciously.
Diviners’ sticks move dramatically in the hand at the places they advocate digging. Pragmatic diviners admit not to know why, and are satisfied with empirical success. This category also includes ancestral peoples who were able to survive in arid regions. Theirs is a tenable position, if unenquiring. Others claim psychic powers, or ‘magnetic influences’ of the water—nonsense, as any physicist will confirm. The stick is held tightly, in a ‘sub-critical’ position in which a small movement of the hand can cause a sudden large movement of the twig. The effect is dramatic, but it is perfectly reasonable that diviners, without being aware of it, tweak the stick at the best location according to the lie of the land.
This explanation was indirectly confirmed by experiments performed by conjuror James Randi in 1979-80, which rule out the psychic explanation. A network of pipes was hidden under a test area, and water passed through different pipes at different times. The diviners asserted in advance that they could locate the path of the flowing water. They performed at chance level.
In summary, experience, no matter how it is dressed up, is the best guide to finding water; and there is nothing psychic about the process.
