Water reuse | U.S. Green Building Council
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LEED BD+C: Homes | v3 - LEED 2008

Water reuse

WEc1 | Possible 5 points


Use municipal recycled water or offset central water supply through the capture and controlled reuse of rainwater and/or graywater.





Note: Rainwater and graywater capture systems are subject to local codes and may require special permits. Note that the water quality should meet local standards, and consult manufacturers’ recommendations to determine the compatibility of plumbing fixtures with graywater. Many states and regulatory agencies require that water going into a toilet or sink meet potable water standards; builders should comply with local codes.

1.1 Rainwater harvesting system (maximum 4 points, as specified in Table 1 below). Design and install a rainwater harvesting and storage system (including surface runoff and/or roof runoff) for landscape irrigation use or indoor water use. The storage system must be sized to hold all the water from a 1-inch rainfall event (equivalent to 0.62 gallons per square foot of roof area used for capture), taking into consideration the size of the harvest system (i.e., 50% or 75% of total roof area, depending on the measure chosen from Table 1 below).


1.2 Graywater reuse system (1 point). Design and install a graywater reuse system for landscape irrigation use (i.e., not a septic system) or indoor water use. The system must include a tank or dosing basin that can be used as part of the irrigation system. Graywater must be collected from at least one of the following:

  • clothes washer;
  • showers;
  • some combination of faucets and other sources estimated to exceed 5,000 gallons per year.


1.3 Use of municipal recycled water system (3 points). Design the plumbing such that irrigation system water demand is supplied by municipal recycled water. This is applicable only in communities with a municipal recycled water program.

Note: A home using a municipal recycled water system cannot receive points under WE 1.2 (Graywater Reuse System) or WE 1.1 (Rainwater Harvesting System) for outdoor applications.

Table 1. Rainwater Harvesting

System size Application Points
≥ 50% of roof area Indoor only 2
≥ 50% of roof area Outdoor only 3
≥ 75% of roof area Both indoor and outdoor 4

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