My uncle was a water dowser for his entire adult life.
He was actually very good at it, was used by farms and large companies looking to build. He would be called in when more scientific means failed.

He used a wooden dowsing stick he got from a tree. Nothing fancy.

I always thought maybe it had something to do with the electrical current running through his body, when he came close to a lot of water.

It's been said it runs in families, although i've never tried it myself.

Interesting article.