|Fig. 1: Chemical synthesis of Polyethylene Terephthalate. (Source: Wikimedia Commons)|
Bottled water use continues to grow around the world, and with it concerns over the environmental, economic, and social implications that come along with the convenience of bottled water. During 2007, the Beverage Marketing Corporation estimated that consumers in the United States purchased over 33 billion liters of bottled water (over 110 liters per person) and sales have increased 70% since 2001. This has surpassed the sales of milk and beer. 
Concerns include waste generation, use of groundwater, hydrologic effects on local surface and groundwater, economic costs, and more. There are also issues of public concern such as the impacts of water extractions on local watersheds, equity issues associated with commercializing a public resource, the environmental consequences of plastic bottles, and the energy (greenhouse gas emissions that result) required to bottle water. A key concern is how much energy it requires to produce and use bottled water. The energy use is not just in the creation of the bottle, because some are transported long distances, which leads to energy costs that are comparable and sometimes even greater than producing it. 
Energy is required to make, package, transport, chill, use, and recycle bottled water and its packaging. The amount of energy depends on a number of factors, such as the location of the water, the distance the bottle must travel to the consumer, the way it is transported, the materials and packaging used, etc. 
The majority of plastic water bottles are made from polyethylene terephthalate (PET). PET is a thermoplastic polymer resin used for a wide variety of purposes, ranging from the production of polyester fibers and clothing to food and beverage containers.  It is produced by the polymerization of ethylene glycol and terephthalic acid, as illustrated in Fig. 1.
Based on lifecycle assessments, it is estimated that the energy required to produce PET resin and including turning it into bottles and some transportation energy is about 108 (th) kg-1 of PET. Producing enough PET bottles to satisfy global demand thus requires
If a barrel of oil contains around 6 ×109 Joules, the energy to produce plastic water bottles is equivalent to approximately
|3 × 1017 Joules
6 × 109 Joules bbl-1
|=||5 × 107 bbl|
or 50 million barrels of oil per year. It is estimated that producing bottle water requires between 5.6 × 106 Joules liter-1 and 1.02 × 107 Joules liter-1. In comparison, producing tap water requires about 5 × 103 Joules liter-1, so bottled water is as much as 2000 times the energy cost. 
Producing bottled water is energy intensive. However, recycling is inefficient and in order to gain the benefits discussed, actions need to be taken to encourage consumers to recycle correctly. Currently, most of what is put in the recycle bin ends up in a landfill because it is contaminated. When recycling is contaminated and too costly to process, the landfills generate more revenues, more virgin materials are sold, and there is more incentive to build incinerators that burn waste to create energy. 
© Laura Jacobsen. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 H. S. Cooley and P. H. Gleick, "Energy Implications of Bottled Water," Env. Res. Lett. 4, 014009, (2009).
 D. Bornstein, "The Conflict of Interest That Is Killing Recycling," New York Times, 22 Oct 18.