LEED CoreConcepts&Strategies_3rd edition - Page 068
Extracted Content
WATER EFFICIENCY
The U.S. Geological Survey estimates that the United States uses more than 400
billion gallons of water per day. The operation of buildings, including landscaping,
accounts for approximately 47 billion gallons per day—12% of total water use. [23] As
residential, commercial, industrial, and other development expands, so does the use
of the limited potable water supply, water that is suitable for drinking. Most buildings
rely on municipal sources of potable water to meet their needs, from flushing toilets
to washing dishes to irrigating landscapes. High demand strains supplies and under
extreme conditions necessitates water rationing. Furthermore, large amounts of
wastewater can overwhelm treatment facilities, and the untreated overflow can
contaminate rivers, lakes, and the water table with bacteria, nitrogen, toxic metals,
and other pollutants. To avoid this damage to the ecosystem, additional municipal
supply and treatment facilities must be built at public cost. Water pumping and
treatment, both to and away from the project, also require energy, whose production
generates additional greenhouse gas emissions.
Green building encourages innovative water-saving strategies that help projects use water wisely. Project teams can follow an integrative process to begin assessing existing water resources, opportunities for reducing water demand, and alternative water supplies. For example, much of the water that leaves the site as waste water or rainwater runoff can actually be used for nonpotable functions.
GUIDING QUESTIONS FOR A TEAM TO CONSIDER MAY INCLUDE THE FOLLOWING:
•• How much rain falls on the site per year?
•• How will water be used on site, and how can the amount be reduced?
•• What are the sources of graywater, such as from sinks and showers, that could be collected and reused for nonpotable uses, such as irrigation?
23 S.S. Hutson, N.L. Barber, J.F. Kenny, K.S. Linsey, D.S. Lumia, and M.A. Maupin, Estimated Use of Water in the United States in 2000 (2004), pubs.usgs.gov/circ/2004/circ1268/pdf/circular1268.pdf.
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