The news that many water companies use dowsing to locate underground water has prompted outraged demands from scientists that they desist at once from wasting time and money on “medieval witchcraft”. They are right to call this practice deluded. But it reveals how complicated the relationship is between scientific evidence and public belief.

When the science blogger Sally Le Page highlighted the issue after her parents spotted an engineer dowsing for Severn Trent Water, the company responded to her query by claiming that “we’ve found some of the older methods are just as effective than [sic] the new ones” (such as the use of drones and satellite imaging). The engineer concerned told her parents that dowsing works for him eight times in 10.

Further inquiry elicited the comment from Yorkshire Water that “although few and far between, some of our techs still use them!”, while Anglian Water said: “There have been occasions where we’ve used dowsing rods.” Le Page says that 10 out of 12 British water companies she approached have admitted to the practice. But “admitted” isn’t quite the right word; what is striking is the jaunty tone of these responses, as if to say: “Yes, isn’t it extraordinary that these old methods work?”

Let’s be clear: dowsing doesn’t work. Le Page’s blog links to detailed experiments conducted in Germany in the 1980s which showed that the dowsers tested weren’t locating water at levels better than random chance. It’s a good lesson in statistical reasoning: that a few individuals did significantly better than the others, for example, doesn’t attest to a rare talent but to the simple fact that this too is an expectation of random outcomes.

The resistance to basic scientific reasoning may seem lamentable, but it shouldn’t surprise us

One of the earliest accounts of dowsing appears in a 16th-century treatise on mining by the German writer Georgius Agricola, where he says it is used to find metal ore deposits, not water. Agricola’s book was noted for its (literally) down-to-earth practicality, although he shares many of the common beliefs of his time – which makes suggestions that dowsing is medieval witchcraft ahistorical. Witchcraft was widely considered to enlist the help of demons, whereas Agricola was the kind of Renaissance humanist who sought to replace such ideas with rational, natural mechanistic explanations for phenomena.

Dowsers might make the same claim today, but there is no known influence in physics that would account for how buried water would move metal rods. It’s not impossible that an unknown law of physics is being profitably exploited by Severn Trent Water, but hopefully we can agree the likelihood is small.

The resistance to basic scientific reasoning and evidence displayed by large businesses that also deploy cutting-edge space technology may seem lamentable, but it shouldn’t surprise us. It has never been more apparent that an inability to make scientifically informed choices is no obstacle to flourishing in modern society. Besides, regarding superstitions as mere ignorance is itself mistaken; they arise and persist for a reason. When Michael Faraday debunked the table-turning of spiritualist seances in the Times in 1853, saying that (as is probably the case with dowsing) the movements are caused by unconscious small hand movements of the participants, it did nothing to quell the craze. The prospect of communion with the dead was too consoling in that increasingly secular age to relinquish.

Another influence at work in the case of dowsing is the seemingly endless propensity of water to attract pseudoscience. An essential and therefore spiritual substance for all of human existence, water has been so thoroughly imbued with miraculous properties that all kinds of unlikely effects seem to require little leap of imagination. The “memory of water” alleged as an “explanation” of homeopathy was only a pseudoscientific veneer for the longstanding idea of water’s healing powers – which continues to support a quack industry of bizarrely treated bottled waters.

Given that company executives and engineers seem no more immune to pseudoscience than the rest of the population, it’s not obvious that better public education about science is going to dispel the modern-day survival of concepts rooted in Renaissance natural magic. (Whether the public should be expected to bear any costs incurred is quite another matter.) Rather, these beliefs need to be understood – and if necessary confronted – in the way that all magical thinking should be: as an expression of desire and the need for consolation.

• Philip Ball is a science writer