The purity of it and I'm guessing at that
Just some information for you in regards to purity of bottled water . . .
First of all, that would require that the bottled spring water you are using is actually purer than the water out of your tap, which is actually not likely. In reality, bottled water of all types have lower water quality standards than the water that comes out of your tap. Bottled water as a whole is regulated for quality by the Food and Drug administration, while municiple tap water is regulated by the EPA. Drinking water standards under the EPA are actually much higher than those of the Food and Drug administration. This is not to say the bottled water has poorer water quality or purity, but it certainly can have.
Further, one must actually investigate the source of the "spring water" in question. One of the major water bottling agencies in our area that bottles "natural spring water" takes their water directly from the Denver Municiple tap. Since the source of Denver's drinking water is springs and snowmelt from the Rockies, they are legally allowed to label their bottled water as natural spring water. Great adversiting gimic isn't it?
In actuality, purity of bottled water is one of the great myths of the 20th century, which was created by companies to sell a product, pure and simple. Unfortunately, so many people have bought into it, that not only are we providing these companies with a huge profit (paying a $1.00 or more for 12 ounces of water that cost the company about 1/12 of $.02 plus bottling costs) and creating huge pollution issues in terms of the plastic bottles that are entering our landfills and environment.
And finally, even if the water came directly from a freshwater spring, you have to consider all the source minerals and groundwater contaminants that can potentially be in the water as it comes direct from the source. Put simply, being inside a plastic bottle doesn't make it pure.