When Fiji water launched an ad campaign that made fun of Cleveland tap water, the city of Cleveland ran tests comparing its water to Fiji water. "These tests showed a glass of Fiji water is lower quality, it loses taste tests against Cleveland tap water, and costs thousands of times more. This story is typical of what happens when you bottled tap water against tap water."
Personally, I filter my Los Angeles tap water because I don't like the chlorinated taste.
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. His new book is Maker Dad: Lunch Box Guitars, Antigravity Jars, and 22 Other Incredibly Cool Father-Daughter DIY Projects