Bottled water versus tap: Which is safer to drink?

Those ubiquitous plastic water bottles have been increasingly vilified in recent years. Los Angeles, San Francisco and Santa Barbara, among others, have banned them from purchase with city funds. A few trendsetting restaurants, and even some markets and hotels, have banned them too.

The trend has left many consumers wondering: Isn't bottled safer than tap?

"Bottled water isn't any safer or purer than what comes out of the tap," says Dr. Sarah Janssen, science fellow with the Natural Resources Defense Council in San Francisco, which conducted an extensive analysis of bottled water back in 1999. "In fact, it's less well-regulated, and you're more likely to know what's in tap water."

Bottled and tap water come from essentially the same sources: lakes, springs and aquifers, to list a few. In fact, a significant fraction of the bottled water products on store shelves are tap water -- albeit filtered and treated with extra steps to improve taste.

It's not news to anyone that tap water can taste funky (too much chlorine, usually) or look discolored (from air bubbles or rust in pipes). But generally, that doesn't mean it isn't safe to drink, says Benjamin Grumbles, assistant administrator for water with the Environmental Protection Agency.

The great majority of the tap water in the country meets the EPA's drinking-water standards, which regulate the levels of roughly 90 different contaminants, including germs such as giardia, heavy metals such as lead and dozens of industrial chemicals.

"If a utility is doing its job and it's well funded, they can take all this stuff out," says Elizabeth Royte, author of "Bottlemania: How Water Went on Sale and Why We Bought It."

Different states do face different contaminants, of course, and the national standards don't cover everything that could possibly get into public water supplies. California, for example, has its own standards to regulate levels of the gasoline additive MTBE and the industrial chemicals called perchlorates.

But even state standards can't account for aging pipes that carry water from public lines into those of people's homes, which can leach copper and lead. Plus, there are certain contaminants water treatment plants just aren't designed to take out, such as medications that wash into the sewers via human excretion or drugs being dumped down the drains. An investigation by the Associated Press this year found traces of pharmaceuticals in drinking-water supplies that serve more than 41 million Americans.