You should try and stay away from plastic bottle water. The plastic (called polyethylene terephthalate or PET) used in these bottles contains a potentially carcinogenic element (something called diethylhydroxylamine or DEHA). The bottles are safe for one use only; if you must keep them longer, it should be no more than a few days, a week max, and keep them away from heat as well.
I use distilled water out of a bladder like cast wine that has no minerals in it. It's called Noble’s Pureau water
