The mechanical systems for this project are geothermal in design. Non-domestic use well water is supplied via a closed loop to an isolated heat pump heat exchanger to provide climate control of the building. The uncontaminated well water is then returned to the ground via a separate well, at a location different from where it was extracted. We would like to use a portion of this discharge well water for site irrigation. Our question is; will this water be considered a non-potable source to help achieve WE Credit 1.2? Our opinion is that this returned well water should be considered non-potable since its use in the irrigation system is secondary to the use of the geothermal system. Also, in using this water in the irrigation system, it is being applied to the landscape and provides a positive impact on the ground water table in the fact that it will replace soil moisture that would have been evaporated from the soil surface and therefore diminishing the moisture levels deeper within the soil profile. A certain portion of this water will also migrate through the soil profile back into the water table.
The applicant is requesting approval to use water extracted from the outlet of an open-loop ground source heat pump for irrigation. The proposed approach does not satisfy the intent of the credit. The irrigation water would be provided indirectly from natural subsurface water to provide a condensing/heating source for the ground source heat pump. The LEED-NC v2.2 Reference Guide states that the credit intent is to "limit or eliminate the use of potable water, or other natural surface or subsurface water resources available on or near the project site, for landscape irrigation." This issue has also been addressed by CIRs dated 1/13/2003, 10/23/2001, and 6/9/2008. Applicable Internationally.