|Talk about an energy drink. The first comprehensive and peer-reviewed energy analysis of a bottle of water confirms what many environmentalists have charged. From start to finish, bottled water consumes between 1100 and 2000 times more energy on average than does tap water.
Bottled water consumption has skyrocketed over the past several years. In 2007, some 200 billion liters of bottled water were sold worldwide, and Americans took the biggest gulp: 33 billion liters a year, an average of 110 liters per person. That amount has grown 70% since 2001, and bottled water has now surpassed milk and beer in sales. Many environmental groups have been concerned with this surge because they suspected that making and delivering a bottle of water used much more energy than did getting water from the tap. But until now, no one really knew bottled water's energy price tag.
Environmental scientist Peter Gleick of the Pacific Institute, a nonprofit research organization in Oakland, California, and his colleague Heather Cooley have added up the energy used in each stage of bottled-water production and consumption. Their tally includes how much energy goes into making a plastic bottle; processing the water; labeling, filling, and sealing a bottle; transporting it for sale; and cooling the water prior to consumption.
The two most energy-intensive categories, the researchers reveal in the current issue of Environmental Research Letters, are manufacturing the bottle and transportation. The team estimates that the global demand for bottle production alone uses 50 million barrels of oil a year--that's 2 1/2 days of U.S. oil consumption. Determining the energy required to transport a bottle isn't as straightforward. Some bottles of water travel short distances, but others are imported from far-off countries, which increases their energy footprint. Gleick and Cooley found that drinking an imported bottle of water is about two-and-a-half to four times more energy intensive than getting it locally, often outweighing the energy required to make the bottle.
All told, Gleick estimates that U.S. bottled-water consumption in 2007 required an energy input equivalent to 32 million to 54 million barrels of oil. Global energy demand for bottled water is three times that amount. To put that energy use into perspective, Gleick says to imagine that each bottle is up to one-quarter full of oil.
"They've done a pretty good job of modeling the bottled-water side," says environmental engineer H. Scott Matthews of Carnegie Mellon University in Pittsburgh, Pennsylvania. But he also says they didn't do enough modeling of tap water to make an adequate comparison between the two. Gleick says that, although the energy for purifying and delivering tap water varies, even in the most expensive cases it is hundreds of times less than for bottled water.
Hyung-Chul Kim, an industrial ecologist at Columbia University, noted that the analysis didn't include the energy recovered from recycling bottles. Gleick says they didn't include that value in their calculations because almost all recycled water bottles end up as carpet, clothing, or toys, not new bottles.