Not surprising that San Franciscans can't tell bottled water from tap water. Penn and Teller claim that there is a difference: American municipal water is not only cheaper, but safer.
SAN FRANCISCO / Spigot water advocates take it to the bottle / Marketed brands no better than city stuff in taste test: "In another of those blind tastings designed to demonstrate what suckers water drinkers have become, ordinary tap water faced off against its high-priced bottled brethren in head-to-head combat.
The idea, according to the earnest young organizers of the first-ever Tap Water Challenge, was to see if people could tell tap water from the $1-a-bottle stuff.
The answer was, they couldn't. "