The Natural Philosopher wrote:

In the ultimate analysis, all observations are taken by human beings,
whose perceptions are just as potentially unreliable as any dowsers.

You haven't personally charted the movements of all the planets to
justify Newtons laws of motion ...

Science derives its strength from other areas then the anecdotality of
its observations.

To dismiss dowsing as unscientific because there is only anecdotal
evidence, is to say nothing.

'Anecdotal' is when Bill tells Ben about something he has seen, and
Ben has to take Bill's word for it because Ben cannot also make the
observation. If Ben can go and see for himself, it's not anecdotal.
That still doesn't make either Bill's or Ben's theories about the
phenomenon correct, but if anyone can test those theories, sooner or
later any holes will be found. Think of it as Open Source in action.

Cold fusion looked at first to be 'scientific', but turned out to be
'anecdotal'. We're back to repeatability. It can, of course, go the
other way: something that is anecdotal can become repeatable when
someone spots a condition which was not being replicated correctly
in trials. It may be that we do not yet know the factor which would
make dowsing repeatable at will. The position of the planets, the
date of birth of the dowser, the number of witnesses...