8-2
WaterSense at Work: Best Management Practices for Commercial and Institutional Facilities
8.
Onsite Alternative Water Sources
After implementing water-efficiency measures through facility modifications or
efficient technologies, facilities can further reduce potable water use by taking
advantage of onsite alternative water sources. An onsite alternative water source
is the water discharge from one application or process that is captured, treated,
and utilized in another application.
1
These onsite alternative water sources can
vary greatly in quality and must be carefully matched with an appropriate end use.
The U.S. Environmental Protection Agency (EPA) has developed comprehensive
guidelines for water reuse to assist all types of organizations in identifying potential
sources and uses of reused water.
2,3
Potential onsite alternative water sources include:
4
••
Rainwater/stormwater
••
Foundation drain water
••
Treated gray water
••
Condensate from air conditioning equipment
••
Filter and membrane (e.g., reverse osmosis system)
reject water
••
Cooling equipment blowdown
Although discharge from single-pass cooling systems can
be a suitable onsite alternative water source, facility manag-
ers should first consider eliminating single-pass cooling, as
described in
Section 6.2: Single-Pass Cooling
.
If elimination is
not feasible, then consider reuse of the discharge water for
another purpose.
Potential uses of onsite alternative water sources include:
5
••
Irrigation
••
Cooling tower make-up water
••
Toilet and urinal flushing
••
Make-up water for decorative ponds, fountains, and waterfalls
••
Processes or other uses not requiring potable water
••
Fume hood scrubbers
General considerations for reuse of onsite sources of water include the quality con-
straints of the source and the potential types of treatment that may be needed to
meet the quality needs of the proposed end use. Although every situation is differ-
ent, Tables 8-1
6
and 8-2
7
provide guidance on typical considerations.
1
U.S. Energy Department (DOE), Energy Efficiency & Renewable Energy (EERE), Federal Energy Management Program (FEMP). February 2011.
Methodology for Use
of Reclaimed Water at Federal Locations
.
2
U.S. Environmental Protection Agency (EPA). October 2012. Guidelines for Water Reuse.
3
EPA. September 2004. Guidelines for Water Reuse.
4
East Bay Municipal Utility District (EBMUD). 2008.
WaterSmart Guidebook—A Water-Use Efficiency Plan Review Guide for New Businesses
.
Pages ALT1-8.
5
Ibid
.
6
Adapted from Hoffman, H.W. (Bill). P.E. Water Management, Inc. January 25-26, 2011. Presentation in Phoenix, Arizona, to the Arizona Municipal Water Users As-
sociation.
7
Ibid
.
Rainwater collection system
