[Cougra]

Check and see if the bottled water source is labeled. Some bottled water is actually RO water which will be ideal.

I've also heard of people collecting rain water to use instead of thier tap water because it's cleaner/purer (In areas that rain alot) then most tap water as well.

I have used bottlewater on occassion in past emergency situations with little side effects but I wouldn't use it on a long term basis unless you know how it's processed.