Unless you are buying spring water, all bottled water and soda water is just RO water with something added back. RO water is as pure as it gets. There are many discussions about RO but if you think about it, the quantity of salts is so miniscule in water that you would get it back from food anyway. Anyway I use a remineralizer as the last step after RO just for the taste. The RO taste is a bit sharp for me.