My engineering teacher showed us last year how to use dowsing rods, it was very odd watching the rods cross over a puddle. The article focuses heavily on the historical "witching" use case for these, which is of course nonsense, but it makes sense that dowsing rods work for decomposing bodies, considering that there's not that much difference between a dead body and a puddle of water.
We don't know how or why dowsing rods work over bodies of water, but they're good enough for our water companies to use. If it was completely luck, then they (hopefully) wouldn't do it.
Dowsing has in fact not been proven to work. There is instead overwhelming evidence that it does not work better than chance.
Wikipedia sums it up nicely, with citations:
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The motion of such dowsing devices is generally attributed to the ideomotor phenomenon,[7][8][9] a psychological response where a subject makes motions unconsciously. Put simply, dowsing rods respond to the user's accidental or involuntary movements.
The scientific evidence is that dowsing is no more effective than random chance.[10][11] It is therefore regarded as a pseudoscience.
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https://en.m.wikipedia.org/wiki/Dowsing
For an entertaining time, check out the late James Randi and his debunking of dowsing
>If it was completely luck, then they (hopefully) wouldn't do it.
I remember an article in Analog, a very long time ago, that touted how dowsing was used to locate mines in Vietnam. John W. Campbell was into a bunch of silly things.
We don't know how or why dowsing rods work over bodies of water, but they're good enough for our water companies to use. If it was completely luck, then they (hopefully) wouldn't do it.