Please do not BUY water. It is environmentally UNsafe and causes harm to the environment in many ways. The production of making plastic is harmful to the environment and the process of recycling plastic is only 40-60%.
If your water has hard minerals in it, for whatever reasons, please do your homework and buy the best house water filter you can get (general upkeep cost of about 6-8 bucks a month maximum) and replace your water filter more often. Then you can buy one of those tap water purifiers too to also reduce the amount of minerals in your house water.
I can guarantee that the "big breeders" do NOT use bottled water on their snakes. Many of them I know just use intense filtration devices, like the ones I stated above but on a much larger scale.
A good thing to know about bottled water- their isn't any regulations for them to follow; whereas, city water has to be tested and regulated on a daily basis for any contaminants and the public notified immediately of any oddities.
As for the chlorine issue with city water- I fill 5 gallon buckets with water and let it sit for a day with an open lid before I use it. This is allows any chlorine to evaporate and dissipate so as not to harm my snakes.
Hope this helps.