The term, "water-witch", a.k.a. "well-witcher", etc., means a dowser, a person skilled at finding water and other objects underground. The practice involves the use of a forked stick or branch, though in more modern times metal rods are used.
A "water-witch" is not a witch. According to my grandmother, our family had a lot of water-witches who were paid for their service. They helped locate places to dig wells.
Being a water-witch in no way implies that a person does conjure work. It's a completely separate practice. Also, the practice spread to Native Americans and Black as the Scott-Irish and other Europeans taught them the art or skill.
One more thing, there wasn't the stigma attached to dowsing or being a water-witch as there were to other traditions. Even very educated, professional people, such as people in the oil industry, once used the services of water-witches or dowsers to locate things. I like to think that the reason why there was no stigma attached to the practice and why water-witches were respected is because finding water is a matter of life or death. It's kind of hard to sit there and condemn someone that saved your family's life by locating a source of drinking water.
Hal Hopper, Professional Water-Witch
Water-Witch In Colorado (Note the traditional forked branch.)
Dowser Find Water In The Desert