Downing the last gulp of a fancy name brand H2O, as well as remembering to toss the empty bottle in the recycling bin, makes you feel pretty good about yourself, right? It shouldn't. Even when the bottles are recycled—and only about a fifth in this country are—there are all kinds of other consequences of quaffing bottled water, says Melissa Peffers, the air-quality program manager for Environmental Defense. (And yes, it is an air-quality issue.)

The containers are often filled in faraway lands, then shipped overseas, transported across the country in trucks, and stored in refrigerators at your local convenience store. Compare that with the environmental impact of turning on your tap, filling a glass, and sipping away.

Anyone who is opting for bottled over municipal for health reasons is misguided, says Peffers: "Most bottled water is just tap water." (And what comes out of your faucet is carefully monitored to follow strict EPA guidelines.) Add in the fact that it's outrageously expensive, especially when set against the (practically free!) alternative, and it is astounding that America's thirst for bottled water seems unquenchable, reaching nearly 30 billion bottles a year.

"My parents' generation never had bottled water. Now it's unbelievable," says Isabelle Silverman, 39, of New York City. The mother of two, an Environmental Defense legal adviser, has made a commitment to going bottle free. "You don't need to schlep it home from the store, and it's economical," she adds. There's a filter on her taps to improve the taste of her municipal water.

Bottled water's role as a status symbol needs to change, notes Peffers. So when a waiter at an upscale restaurant offers "still or sparkling," that's no reason to forget your convictions. "Don't be afraid to say, 'I'll have tap.' Say it loud enough that the other tables nearby can hear you," Peffers says. "And then spend that money on a dessert."