I'm interested to know what they test your water for.

Is it just minerals or bacteria as well?

We have a borehole (about 250 feet) at our house in the Lancashire Pennines and our problems are too much iron, too much manganese and too acid, all of which are corrected by a collection of cylinders and pipes. It isn't perfect though, we seem to get through a lot of hand lotion!

In the UK every borehole drilled contributes data to a national database so that slowly we are building up a picture of what to expect below ground.