I have been using well water for several years now with no problems. I just use a basic water conditioner that also removes heavy metals, and a tiny bit of salt just to keep maladies at bay.
We have really nice well water though, so you want to be sure that your well water is not too hard or such first. If you drink it and it works out really well, then it is probably better than tap water, that is for sure. :)
Make sure temperature is between 75 and 80 degrees- I have ours in a 2 1/2 gal bowl with a tiny heater designed for that type of set up. I change the water weekly. Plants help too if you can get them to grow.
