Water Use (3.0)

Credit Language

OP 3: Water Use – version 3.0


  • 3.1 Potable water use per person
  • 3.2 Potable water use per square meter
  • 3.3 Systems for water recovery and return
  • 3.4 Ratio of water recovered/returned to total water withdrawal

Questions & Answers

  • How has this credit changed between STARS Version 2 and Version 3?

    • Water use performance is now assessed against a benchmark for an institution’s peer group (basic institution type). Baseline data is no longer required. Learn more about how benchmarks were calculated.
    • Reduction in total water withdrawal per unit of vegetated grounds has been dropped due to concerns about the validity of the metric.
    • Indicator 3.3 incorporates qualitative information about rainwater harvesting systems, water recovery and reuse, and green infrastructure (GI).
    • A new indicator (3.4) requires data on the estimated annual volume of water recovered and/or returned on-site. This indicator is weighted more heavily for institutions located in areas of high water stress.
    • A comprehensive list of differences can be found in the STARS 3.0 Summary of changes.

    How do we determine which peer group our institution falls under? 

    Institutions must select from among the following peer groups, which typically aligns with Institution Type categories reported under PRE 3: Institutional Characteristics. Peer group selections should be consistent with PRE 3 and across all applicable credits. 

    • Associate’s colleges, short-cycle institutions and pre-tertiary schools – This category includes higher education institutions where all degrees are at the associate’s level, or where baccalaureate degrees account for less than 10% of all degrees.
    • Baccalaureate colleges and boarding schools – This category includes Colleges and universities where baccalaureate degrees represent at least 10% of all undergraduate degrees and where fewer than 50 master’s degrees or 20 doctoral degrees are awarded annually. 
    • Master’s colleges and universities – This category includes colleges and universities that award at least 50 master’s degrees and fewer than 20 doctoral degrees annually.
    • Doctoral universities and research institutions –  This category includes institutions that award at least 20 research/scholarship doctoral degrees annually, including doctoral degrees that qualify recipients for entry into professional practice. 

    What are some examples of water recovery and return systems? (Indicator 3.3) 

    Qualifying examples for each 3.3 criterion are listed below. 

    • Harvesting rainwater on-site for storage and use – Examples include rain barrels, detention ponds, and other rain catchment systems in which water is stored and reused. 
    • Recovering water on-site for reuse – Examples include the recovery and reuse of greywater, sump pump water, air-cooling condensate, reject water from water purification systems, and wastewater.
    • On-site green infrastructure (GI) – Examples include rain gardens, bioswales, permeable pavement, and nature-based wastewater systems.

    Are there other credits that ask for the same information?

    Gross floor area of building space is required under the following credits:

    • PRE 3: Institutional Characteristics
    • OP 3: Water Use
    • OP 5: Energy Use
    • OP 6: Greenhouse Gas Emissions
    • OP 12: Waste Generation & Recovery

    Full-time equivalent student enrollment and Full-time equivalent of employees are reported under the following credits: 

    • PRE 3: Institutional Characteristics
    • OP 3: Water Use
    • OP 5: Energy Use 
    • OP 6: Greenhouse Gas Emissions
    • OP 12: Waste Generation & Recovery
    • OP 14: Commute Modal Split

    Generally speaking, these figures should be consistent across credits if the same performance year is being used. To simplify reporting, the Reporting Tool will allow you to copy the figures reported under the Institutional Characteristics into other credits. If it is necessary to deviate from one or more PRE figures when completing a credit, the rationale for doing so should be recorded in the Notes field for the affected credits (e.g., difference in reporting timeframe).  

    See related article on Can information be shared between credits?

Suggestions for Institutions

  • Floor area figures must be reported in square meters. To convert square feet, multiply by 0.09290304.
  • Water figures must be reported in cubic meters. To convert US gallons, multiply by 0.00378541. To convert liters, multiply by 0.001.
  • Review the Institution Type classification reported under PRE 3 and ensure that the selection under this credit aligns with what is reported in PRE. 

Potential Data Quality Issues

  • Water risk – Institutions should report the level of PHYSICAL RISKS QUANTITY as determined by the World Resources Institute Aqueduct Water Risk Atlas. 
  • Indicators 3.1 and 3.2 – Peer Group – The selection made for peer group must be consistent to what is reported under PRE 3 for Institution Type.
    • US institutions: Refer to the latest Carnegie Basic Type Classification for your institution to ensure that the most accurate selection is made.  
  • Data consistency: Full Time equivalent student and employee and gross floor area figures should be consistent between PRE 3, and this credit if the same Performance Year is used. Valid discrepancies should be clarified in the Notes field.
  • Indicator 3.3. Affirmative responses must be supported by information provided in descriptive fields. If claiming Criterion C (collecting and returning water to surface water or groundwater through on-site green infrastructure), the descriptive response should include a summary of the institution’s rain gardens, bioswales, permeable pavement, and nature-based wastewater systems. “
  • Indicator 3.4. Uncommon for institutions to earn close to full points. If a high Ratio of water recovered/returned to total water withdrawal is reported (e.g., .7 or higher), the descriptive response should provide details on how such high rates of water recovery were achieved. 

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