When you buy bottled water, there are a couple of things to consider. First is the water itself. Is it just tap water that’s been put into a bottle? Is it tap water that’s been filtered and then put into a bottle? Or is it actually mountain spring water taken straight from the spring and put into the bottle? Tap water has a high risk of containing chemicals, pesticides, heavy metals and even toxins like arsenic. If it’s been filtered with something like reverse osmosis, most of these things will be removed and I would consider it safe. But if it’s distilled, all of the good minerals will have been removed as well as the bad stuff; and this water can then leach minerals from you. If the water is straight from the spring, and the spring is clean, it should be free of contaminants and still contain all of the good minerals.
Secondly, you need to consider the bottle. Soft plastic can leach estrogen-like compounds into your water, especially if the bottles have been shipped from somewhere far away and have spent any time in the heat. Hard plastic bottles tend to leach a little less, but nothing plastic is ‘leach-free’. Currently there is a lot of hype about bottles that are “BPA free”. BPA is a compound that was put into plastic to make it clear. It has been shown to have deleterious effects on your health, so many companies are removing it. I just wonder what new chemical they’ve replaced it with, since the bottles are still clear. You’re better off using a glass bottle that has no risk of leaching anything into your water.
So, ideally you filter your own water at home and carry it around in a clean, glass bottle. When you’re out and about, you can look for water in glass bottles and check the source of the water. Otherwise, it may come down to picking the lesser of two evils, which I am not sure what that would be; tap water with all of the contaminants or water that’s been sitting in and soaking up chemicals from a plastic bottle.