The concept of bottled water is a phenomenon to most. Some people are baffled at the idea of spending $1+ for some water. They've done studies on bottled water and some have concluded that bottled water is sometimes no better than the water that leaves our faucets.
When at a restaurant, your server asks you whether you'd like bottled or tap water. These days, we're all about not looking "cheap" so for appearances alone, some will opt for bottled. Tap can be considered degrading. As for me, as long as the water from the faucet is clean, I'm all for tap. I grew up in Utah where the water is actaully very good. Restaurants have now realized that they don't want their customers feeling lower class so now the term "tap" has changed to "flat."
I find it interesting that over time, words we say or things we do regularly, become offensive to people. For example, words that carry gender. It's impolite to call a police officer a policeman. There are other changes such as stewardess to flight attendant, mailman to letter carrier or postal worker, chairman to chairperson or chair, spokesman to spokesperson, anchorman to anchor, wife or husband to spouse, mothering to parenting or nurturing, housewife to homemaker...
Makes me wonder what "flaw" will be thought of next.