P3.2: Reduce Water Use for Landscape Irrigation

(Required)

INTENT

Conserve water resources and minimize energy use by reducing the use of potable water, natural surface water, and groundwater withdrawals for landscape irrigation after the establishment period.

REQUIREMENTS*

This prerequisite applies only to long-term water use for the final vegetated area beyond the establishment period.

• Reduce or eliminate the use of potable water, natural surface water, (e.g., lakes, streams) and groundwater withdrawals for landscape irrigation (beyond the establishment period).
• Use the U.S. EPA WaterSense Water Budget Tool (or local equivalent for projects outside the United States) to identify the baseline case and water savings (www.epa.gov/watersense/water_budget/application.html).
  • Reduce water usage by at least 50 percent from the baseline case beyond the establishment period.
    • If the water source does not come from a potable water source, local health standards must be met.
    • Install water meters to record and measure water usage to compare to the established baseline.

OR

• Design the landscape to not require a permanent irrigation system.
• Ensure the sections of the site maintenance plan (see O+M P8.1: Plan for sustainable site maintenance) are complete and describe the anticipated watering schedule as well as the process for maintaining non-potable irrigation water sources.

Exemptions:

• Water volume used for the following purposes may be included or excluded from irrigation calculations at the project team’s discretion:
  • Water used during establishment period
  • Water used to irrigate non-commercial food production gardens. Irrigation used on edible plants should not harm human health. (See HHWB C6.7: Provide for on-site food production.)
  • Water used as required by local regulations in fire-prone areas for fire suppression systems
  • Water used for athletic fields (if vegetated)

RECOMMENDED STRATEGIES

Reduce potable water use with any combination of the following items and methods:

• Design the site to maximize the use of captured stormwater for landscape elements
• Design the plantings, soils, and other features to be self-sustaining with natural precipitation only. Limit water use to time of planting only.
• Plant at the optimal season for your region to reduce or eliminate the need for watering for establishment.
• If turf grasses are to be used, they should be regionally appropriate and minimize post-establishment requirements for irrigation.
• Improve water-retention capacity of soil by increasing organic matter (e.g., adding compost)
• Design irrigation systems in such a way that trees, shrubs, and ground cover are irrigated in separate hydrozones. This way, watering can be discontinued by zone as plants become established.
• Use high-efficiency equipment (e.g., drip irrigation) and climate-based controllers for irrigation systems
• Reuse graywater, captured rainwater, HVAC blowdown, or condensate water for irrigation to decrease potable water use for irrigation and to create a net benefit to the local watershed by making the landscape part of the natural water-treatment process.
• If graywater or wastewater is to be recycled for landscape irrigation, consider conducting chemical tests to determine suitability for reuse on intended vegetation.
• Use water treated and conveyed by a public agency specifically for non-potable uses

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