Nowadays, water engineers can use a variety of hi-tech technologies to find underground water. For example, acoustic doppler current profilers detect water movement within a pipe; electrical resistivity tomography devices detect groundwater by through electrified wires dropped into the ground, and magnetic resonance sounding equipment finds underground water using the technology of MRI scanners.
But before all this wizardry existed, people depended on dowsing (otherwise known as water divining) to ‘see’ into the ground and locate things such as water wells, hidden metal, oil, buried treasure and even lost golf balls! And rather than using equipment that costs a bucket load, modern day dowsers use the same technology: simply placing either two bent rods or a forked stick in front of them and walk over a target area to ‘find’ water. When the stem of the twig pulls towards the ground or the two rods cross over, it indicates that water is near. This process can then be repeated from a different direction to pinpoint the location.
Dowsing has been practiced for millennia and, as with anything with such a history, there are many enthusiasts who swear that it works; some water engineers even use it in their professional work. Dowsing is a practice that has also been extended to finding missing people (although a few more items are needed, namely a map and a pendulum) and is described as map dowsing.
But finding underground water relies not just on technology, but on an understanding of the land – a realisation that certain areas are more likely to accumulate water than others. Such knowledge of geology and the landscape is used by hydrologists and dowsers alike – whether they realise it or not. And so most scientists argue that the dowser’s twigs or rods move not through detection of ‘earthrays’ (the force that dowsers believe exist) but through the ideomotor effect, whereby the dowser unknowingly moves the device. Much like how tears can be brought on emotions, tiny ideomotor movements and twitches are driven by unconscious beliefs, in just the same way that involuntary hand movements drive an Ouija board reading.
It is likely that an experienced water dowser will have learnt from previous failures and successes in which areas underground water commonly occurs – in the same way a hydrologist can make a best guess from their understanding of geology. And so while a hydrologist may say that they have a hunch about underground water, a dowser will let it come out in their sticks.
Answer By Dr Stu and Chloe Westley
Read more: Water Dowsing by USGS (a thorough appraisal)