Additional Factors Expand Size of Products' Water "Footprints"

As global industries begin to measure and report their water use, they should keep in mind all the water they consume, says the Netherlands nonprofit Water Footprint Network, which has developed a new metric for calculating water footprint.

Typical reporting only measures

blue water, the amount of fresh surface and groundwater consumed, but the organization advocates a more comprehensive calculation that also encompasses

green water footprint and graywater footprint.

Green water is precipitation that is stored in soil and never makes it into groundwater because it is absorbed by plants or evaporates; the green water footprint of an agricultural or forestry product is the amount of rainwater consumed during the production process.

Graywater footprint is the amount of fresh water that would be needed throughout the product’s entire life cycle to dilute polluted water enough to meet ambient water quality standards.

Expanding water footprint calculations to include these two indicators makes them larger than previously considered. The Nature Conservancy, which helps companies measure and reduce their water footprint, is advocating use of the new metric as a global standard. More information is available at www.waterfootprint.org.

– Paula Melton