estimated based on how much money industries spend on water in a given year. Michael Blackhurst, the first at the University of California, Water might be locally renewauthor of the paper and a Ph.D. Berkeley, described the analysis able, but it is also a globally ficandidate working under Henas seminal. “It fills a very impornite resource with shifting drickson, says he was surprised tant gap,” he says. “The work availability. Industry accounts that most water usess60% on comes nearly 30 years after the for most of the water used in the averagesare indirect. “That last reliable set of industrial waU.S., yet industry-specific estiturned out to be a significant ter use data were made availmates of that consumptionslast finding,” he said. “A lot of that able. They used the best tallied by the U.S. Census Buwater consumption is hidreau in 1982sare outdated. den because companies That is a problem because don’t pay for all of it.” Inindustrial sectors need to deed, among 96% of sectors budget water uses correctly evaluated, indirect uses exfor effective planning. ceeded direct uses throughIn this issue of ES&T, out product supply chains. Chris Hendrickson and colHendrickson and Blackleagues address that shorthurst emphasize that their age by estimating water data are national findings withdrawals for more than that do not apply region400 industry sectors (Envially. Moreover, they could ron. Sci. Technol. 2009, As shown by this cumulative distribution function, suponly track withdrawals, and DOI 10.1021/es903147k). ply chain (indirect) water use exceeds direct use for were unable to determine Their analysis accounts not 96% of all 428 sectors evaluated. how much water was rejust for direct usesssuch as available data and methods and turned to the system or recycled. crop irrigation in agricultures provided a practical piece of reThat is a key limitation, Henbut also for indirect uses search that will be useful for a drickson says, because water throughout a sector’s supply long time.” that gets degraded during induschain. For instance, irrigation Hendrickson and colleagues trial processes might not be suitwater would be a direct use for started with total water uses for able for future uses. Yet Horvath agriculture but an indirect use six industry sectors defined by says the LCA methods applied in for the grocery sector. “We’re the U.S. Geological Survey the analysis reveal a comprehentrying to help industries track (USGS). These “umbrella secsive footprint of water use assoand make better management tors” are extremely broad. For ciated with products and decisions about how they use instance, the irrigation sector services throughout the U.S. water,” says Hendrickson, a proconsumes ∼190 trillion liters (50 economy. “It gives a way to look fessor of engineering at Carnegie trillion gallons) a year, but USGS at how we might use water more Mellon University in Pittsburgh, does not break that value out by efficiently,” he says. “It allows us PA. “If you’re trying to minimize crop. This is where Hendrickto hone in on the sectors that environmental impacts, then son’s analysis comes into the use the most water so we can you need to know about these picture. He and his colleagues start generating ideas and techupstream demands,” he adds. took each of 428 industrial “subnologies for better manageBecause reported consumption sectors” defined by the Bureau ment.” rates by sector are no longer of Economic Analysis (BEA), and available, Hendrickson and his —CHARLES SCHMIDT assigned them to their correcolleagues had to estimate likely sponding USGS sectors. They values and use them with a then used other relevant data to method called economic inputdetermine how much of the output life cycle analysis (EIOUSGS water totals were conLCA). By necessity, they had to sumed by these more narrowly combine disparate data sets for defined categories. Crop-specific different sectors, gathered over irrigation values, for instance, varying time periods. Hendrickwere estimated using data from son acknowledges the results are the U.S. Department of Agriculsubject to considerable uncerture. Likewise, “purchased” voltainty and variability. But Arpad umes consumed by sector were Horvath, an associate professor CHRIS HENDRICKSON
Water Uses by Industry Revealed
9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / March 15, 2010
10.1021/es100386j
2010 American Chemical Society
1882
Published on Web 02/17/2010
