I have Reverse Osmosis water filter system here. Makes water taste a lot bitter but once you get used to it ( takes at least a week) it becomes fine. But once you get used to RO water, you can easily spot change when you are drinking non-RO water.
I've heard other people say this too. It just goes to show you that bottled water and water from a filter aren't obtaining the same results, otherwise you'd have the same taste as an RO system.