But many consumers know better. In fact, one of the top bottled water brands, Coca-Cola Co.'s Dasani, fills its bottles with water from East Bay Municipal Utility District - the very same water that comes out of the tap in Danville and Alamo.
"What they tell us … is that they put it through extra filtration and that that extra filtration makes it even better than EBMUD water," said EBMUD lobbyist Randy Kanouse. "And they may be right."
Or they may not be, suggested a study published this month by the Environmental Working Group, a public health advocacy organization. Its authors tested 10 top brands of bottled water in several states including California, and found 38 different contaminants in the water, such as bacteria and caffeine.
"Americans cannot take the quality of bottled water for granted," the study concluded. "Indeed, test results like those presented in this study may give many Americans reason enough to reconsider their habit of purchasing bottled water and turn back to the tap."
Yet while a growing number of consumers are sticking to the tap, many believe that bottled water tastes better, is purer, and is safer than water from the kitchen faucet. And they're willing to pay the price.
To get EBMUD tap water in their homes, the average family pays around $3 per 1,000 gallons of water. Dasani pays EBMUD a similar rate. Compare that to bottled water, which costs consumers roughly $7.50 for one gallon's worth, depending on whether the bottles are purchased in bulk or individually.
That means the water inside a $1 plastic bottle actually only costs about three-tenths of a penny, noted EBMUD director John Coleman.
"People complain about gas being $3.50 a gallon and they're willing to pay $7.50 a gallon for bottled water," he said. "That's absurd when they can get the same quality from their tap."
Is it the fancy names and pristine images on the labels making people willing to shell out the extra dough? Or is there actually a difference in the water?
Bottled vs. tap
Tap water and bottled water both have to meet requirements to assure they're safe to drink. But they are each held to different regulatory standards.
Tap water is considered part of the public domain and thus is regulated by the state Department of Public Health as well as the Environmental Protection Agency. Bottled water, considered a food product, is regulated by the Food and Drug Administration.
"Requirements on the state and federal levels for tap water are higher than for bottled water. They don't have to meet the stringent requirements that we have to meet," said Coleman. "You cannot buy a bottled water that's going to be more healthy for you than our tap water."
Indeed, Danville area residents are fortunate: EBMUD water exceeds standards and is considered one of the highest quality municipal waters in the country.
Dasani, too, takes pride in the quality of its product.
"We do use municipal water to bottle Dasani," said company spokesman Ray Crockett. "I do know that the FDA has fairly rigorous requirements for what they call purified water."
To meet those requirements, the municipal water goes through the company's filtration process. The water is first filtered for sand, carbon or other microns, and again for any residual odors or tastes, according to the Dasani Web site. It then goes through a reverse osmosis process - a high pressure, molecular level filtration.
After that, certain minerals, like salt, are added back in for taste. And finally, the water is ozonated, a disinfection step to prevent any future contamination.
Tap water advocates point out that while municipal water has to make public the results of its regulation tests and report any violations of standards to the Department of Public Health, bottled water companies are not required to do this.
"They (consumers) just assume that because it's in a store it must be healthy and safe," Coleman said.
People may also assume, water is water - it's all the same. "It isn't, you know, it really isn't," said Kanouse. "There are so many Californians who have come to recognize that water is so important, and we consume so much of it, and we feed our children water. We should know what's in it."
What's in your water?
Substances such as lead, iron, mercury, sulfate, bacteria, caffeine, fertilizer and plastic-making chemicals can be in the water we drink. Depending on the source of the water, different contaminants can be found.
For example, water taken from the Delta will require more filtration than water from the Sierra. The pipe the water travels in makes a difference as well; if you can isolate the water from fertilizers, pesticides, sewage plants, etc., it will be cleaner, Kanouse said.
"There are a lot of things in the water that are scary," said Shannon Williams, a certified nutrition consultant in Danville. "I do suggest to clients that they go with filtered water. Because, yes, tap water does have a lot of contaminants in it, and it's those unseen, unsafe contaminants that we need to be wary of."
She said people sometimes throw prescription medications down the toilet which can end up in the water system, as well as pesticides and herbicides from agriculture, or pollutants from rain.
"For the general population it's not much of a concern, especially here in Danville," noted Danville registered dietician Christina Bode. People who live in cities with lower quality municipal water or rural areas using well water have to be more careful.
Health aside, certain minerals can affect the smell or taste of drinking water. For example, some people can taste iron even at low levels, and water exposed to sulfate may have a distinct smell.
"These are some of the naturally occurring substances that can affect taste and odor that will not have a health effect - won't make you sick, won't cause any disease - but can be noticed by the common person, the average person who takes a drink of water and says, 'Oh, I don't like this,'" said Kanouse.
Hooked on the bottle
Many people predict that bottled water sales will taper off as people become hip to the environmental impact, pocket cost and questionable health benefit of the product.
"There are a lot of environmental negatives to using bottled water," said Coleman. Water is heavy – about 8 pounds per gallon – and that weight has to be shipped from the source to each store, he said.
Crockett said one of the reasons Dasani bottles local municipal water is to reduce shipping and lower the company's carbon footprint.
Though most bottles are made with recyclable plastic, a high number of them never make it to the recycling bin, ending up in overflowing landfills. "I don't think we're able to recycle them as quickly as we're using them up. And that's cause for concern in my opinion," said Williams.
Coleman estimated that fewer people are drinking bottled water because of its impact on the environment. "I think people are more environmentally aware," he said.
But for the time being, there's no doubt that many consumers are hooked on bottled water.
Bottled water sales have increased each year of the last decade, and it is the second most consumed drink in the country, after soda. As Kanouse put it, "Today, the little plastic bottle is ubiquitous."
But though sales are going up, the rate of increase is slowing. Last year the sales growth was the slowest since the early 1990s, before the trend really took off, according to an annual market report from the Beverage Marketing Corp.
Sales are also slowing in California, where the consumers buy more bottled water than in any other state. More than 1.8 billion gallons of bottled water were sold in California in 2005. The number rose to nearly 2 billion in '06, a 9.1 percent increase. Sales rose again in 2007 at an increase of only 5.6 percent.
At Yellow Wood Coffee and Tea in Alamo, sales have gone up. "We've been selling about 10 percent more water bottles than last year," said manager Shannon Steelman.
"I don't know if it's that people in the area we live in prefer water bottles more," she said. "When you picture bottled water, you'd think it would be the safest option."
At Peet's Coffee and Tea in Danville, manager Traci Hill said she's noticed little change in bottled water sales. Those that choose the bottle over the tap do it for convenience, she said.
"In the past 10 to 20 years, bottled has replaced tap for so many Californians," said Kanouse. Just look around at a soccer game or a Little League game and you'll see parents drinking bottled water in the stands, and giving it to kids at half time, he said.
Both Williams and Bode recommended putting a Brita filter on your tap at home and purchasing a refillable, metal water bottle to carry around. Refilling a plastic bottle is not advisable, because chemicals from the plastic can leech into the water.
"To cut down on cost, to cut down on waste, I think that's the smartest way to go," Williams said. "I'm glad people are drinking water. So that's important. But I'd like to see them go one step further and be concerned about the quality of water they're drinking."
Consumer right-to-know legislation
EBMUD co-sponsored a consumer right-to-know bill requiring bottled water companies to list the source of their water on the label, and make the results of their water quality tests available to the public via Web site or by calling an 800 number.
The bill, introduced by State Sen. Ellen Corbett (D-San Leandro), passed last year and will go into effect July 1, 2009. The new rule applies to all bottled water retailers in California.
"People have a right to know what's in their water," said Randy Kanouse, who lobbied to pass the bill.
The bottled water industry strongly opposed the bill, saying it would put stricter requirements on it than on other food products, and do little to help ensure safety.
"Ten years ago, 15 years ago, they could have successfully argued that bottled water is really a soft drink. But today they cannot make that argument," said Kanouse. "This was not about claiming their water was unsafe … this was really about consumers' right to know."