The True Cost of Bottled Water
In a previous Eco-Tip (15 February 2007), we discussed the ruse that is bottled water. For those of you just tuning in, the short story is that you're paying for the packaging of water that is just as likely to have come from a municipal faucet as to be less clean than what comes out of your own tap.
There is, of course, an energy cost to the packaging and distribution of said little bottle of deception, but what, exactly, is that cost?
In a the 19 February 2009 issue of Environmental Research Letters, authors P.H. Gleick and H.S. Cooley published "Energy Implications of Bottled Water." Although the writers caution that, since sources and distribution of bottled water are so varied, it is not possible to come up with a single figure, they have chosen several water sources and traced the energy cost of their distribution.
As of 2006, about 44% of bottled water in the United States came from municipal water sources. Sold as "purified water," most comes from the Coca-Cola Company, Pepsi Cola Company, and Nestle. These bottlers take municipal water from the nearest source to the bottling plant, with or without filtering it, and seal it in a bottle. The other 56% of bottled water comes from groundwater or protected springs, some of which are as far away as Fiji and France, and this water carries no guarantee that it is are any more pure than what comes out of your faucet.
The authors refer to energy cost in megajoules; translating that, a barrel of crude oil yields 6000 megajoules and a gallon of gasoline yields about 132 megajoules.
The energy tracking begins at the point where plastic bottles are made. Natural gas and petroleum are used to supply the energy required to mold polyethylene tetraphthalate (PET, the "1" you see on the recycling code on the bottom of your bottle) into bottles. The average energy needed to make one bottle is approximately 0.03 gallons of gasoline. A case of 24 bottles of Philadelphia water, then, would cost you almost three quarters of a gallon of gas. And that’s just to make the bottles.
Preparing the water for those bottles takes energy too, but not nearly as much as manufacturing the plastic. Water treatment varies tremendously, from ultraviolet irradiation to reverse osmosis. Although there are energy costs for getting the water to the bottling plant, the authors analyzed just the purification step and determined that the most energy-intensive methods require only 0.02 megajoules per liter (1.5 ten-thousandths of a gallon of gasoline).
Once the water is ready, the bottles must be cleaned, filled, and sealed at the average energy cost of 0.014 megajoules per bottle, or one ten-thousandth of a gallon of gasoline per bottle.
Now the bottles must be transported. The cost variation is large here, since it depends on how the bottles travel and where they’re going. Bottled municipal water doesn't have to travel very far, since the bottlers serve local markets. Spring water, however, tends to go a lot farther from its source. So, locally-produced water costs about 1.4 megajoules (one one hundredth of a gallon of gas) per liter. However, spring water transported across the ocean from Fiji or France to the United States can cost as much as 5.8 megajoules (44 times more gasoline) to get to the supermarket.
Once on display at the store, bottled water is often refrigerated. If the water is also refrigerated at home, the final energy cost would average 0.2 megajoules (1.5 one hundredths of a gallon of gasoline).
Putting all these energy costs together, Gleick and Cooley estimate that a liter of bottled water takes anywhere from 5.6 to 10.2 megajoules of energy to create. That’s 0.043 to 0.077 gallons of gasoline required to make every liter of bottled water.
That's a lot of gasoline for something you could just get from your tap, and means the energy cost of bottled water is about 2000 times that of tap water.
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"Energy Implications of Bottled Water," by P.H. Gleick and H.S. Cooley, appears on pages 1-6 of Volume 4 of the 2009 issue of Environmental Research Letters.
