A holistic approach to design, construction, and demolition that minimizes the building’s impact on the environment, the occupants, and the community. (California Building Standards Commission)
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A pattern of resource use that aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but in the indefinite future. (Wikipedia)
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A systematic approach to achieving human development in a way that sustains planetary resources, based on the recognition that human consumption is occurring at a rate that is beyond Earth's capacity to support it. (Answers.com)
 A practice that ‘meets the needs of the present without compromising the ability of future generations to meet their own needs’ (1987 UN Convention on Environment and Development)
Many jurisdictions (municipalities and other local authorities and state governments with the power to mandate, approve, disapprove, or influence project design and construction) are developing guidelines and minimum standards for new construction and renovations. These actions mandate or “suggest” design or construction practices, technologies, performance thresholds and metrics in a variety of categories including, but not limited to:
Category Generally inclusive of…
Siting and Site Sustainability Site selection, site development, stormwater control, landscape, mitigation of heat island effect, and light pollution reduction.
Energy Efficiency and Metering Energy efficiency for buildings and appliances, for on-site renewable energy systems, and for energy metering.
Indoor Environmental Quality Indoor air quality, ventilation, environmental tobacco smoke control, outdoor air delivery monitoring, thermal comfort, building entrances, acoustic control, daylighting, and low emitting materials.
Atmosphere, Materials and
Resources
Construction waste management, refrigerants, storage and collection of recyclables and hazardous materials, and reduced impact materials; life cycle analyses and assessment; transportation of materials.
Construction and Operation
Plans
Water Use Efficiency and
Metering
Building commissioning, building acceptance testing, measurement and verification, energy and water use reporting, durability, transportation management, erosion and sediment control, construction, and indoor air quality during construction.
(see below)
Typical water use efficiency categories within many of the national green building programs include:

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Plumbing fixtures and fixture fittings
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Residential appliances (clothes washers, dishwashers)
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Water treatment equipment (softeners, filtering systems)
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Landscape & landscape irrigation
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Pools, fountains, and spas
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Cooling towers
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Decorative and recreational water features
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Water reuse & alternate sources of water (graywater, rainwater and stormwater, cooling condensate and cooling tower blowdown, foundation drain water)
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Specialty processes, appliances and equipment (food service, medical, laboratories, laundries, others)
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Metering & submetering
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Once-through cooling
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Vegetated green roofs
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Building water pressure
It is important to understand the difference between green building standards and green building guidelines, because while guidelines do provide thresholds for efficiency, compliance is usually voluntary. On the other hand, standards provide definitive efficiency thresholds, but are written in language that is enforceable and is also readily adopted by reference into codes and other regulations.
Water efficiency practitioners must become involved in the larger green building task. Because many local green building programs fail to consider or emphasize water efficiency, instead focusing on other important environmental issues, there is a need to bring water efficient practices, designs, and products to the attention of the sponsors and originators of these programs.
Here are some suggestions for increasing the profile and influence of water efficiency in these efforts:
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Learn about and monitor the green building programs that are operating in your area, including both voluntary guidelines and mandates that might be promulgated by your local municipalities.
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Actively seek out and provide advice and input to local governments, the programs, and their managers on water efficient practices and technologies and their importance to local area sustainability.
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Monitor the national standards that are likely to be candidates for adoption (and enforcement) by the local authorities within your own area and by your state government. Where the local or state mandates are still being considered and developed, provide advice from a national viewpoint in order to achieve commonality.
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Be observant for greenwashing and the tendency to endorse or adopt practices, products, and initiatives that, in fact, are water wasting. To recognize legitimate practices and products and discern when greenwashing is occurring, always look for independent studies that verify the claims made for water efficiency by the advocates of those practices and products. Ask manufacturers to substantiate their claims with real world proof of savings and consumer acceptance.