[stickfigure]

This is far too charitable. The first question we should ask is "does it actually work?" and the answer is NO.

The wikipedia page lists quite a few scientific studies that establish this. The net summary is:

The scientific evidence shows that dowsing is no more effective than random chance. It is therefore regarded as a pseudoscience.

https://en.wikipedia.org/wiki/Dowsing

[the_fury]

You have to be careful of what you mean by "does it actually work".

Does the dowsing find water hidden in a random spot or is the dowser tapping into subconscious knowledge about the land to find it. The parent is talking about the latter.

Look up "Ideomotor phenomenon" in your source. It's right above the pseudoscience bit.

[eesmith]

It's not like subconscious knowledge must be valid subconscious knowledge. The ideomotor phenomenon is an expression of internal belief, which may be little different than a wild-ass guess.

There's no evidence that the dowser is tapping into subconscious knowledge in a way that gives results any better than - or different from - chance.