Measures to improve water efficiency, including limitations on full-flush volume for toilets and use of municipal reclaimed water for irrigation, are being proposed for a green building standard.

ANSI/ASHRAE/USGBC/IES Standard 189.1-2011, Standard for the Design of High-Performance, Green Buildings Except Low-Rise Residential Buildings, provides a design standard for those who strive for high performance buildings. It covers key topical areas of site sustainability, water-use efficiency, energy efficiency, indoor environmental quality and the building’s impact on the atmosphere, materials and resources.    

The changes regarding water are proposed via addendum v, which would limit the full-flush volume for all toilets to 1.28 gpf and limit kitchen faucet capacity to 1.8 gpm. Research shows dual-flush toilets in nonresidential settings are not used in the 2:1 full-flush to partial-flush ratio as anticipated. Instead, the full-flush option is almost always employed. The kitchen faucet maximum capacity is being changed to reflect the current water efficiency standard of 1.8 gpm established by various green codes.   

The proposed addendum also would set limits on the use of municipal reclaimed water for irrigation. Municipal reclaimed water is highly treated usually to drinking water standards and often in short supply. The growing use of municipal reclaimed water for groundwater recharge of potable water supplies increases its value.   

Its temporary use in above-ground irrigation systems is allowed, however, during the vegetation establishment period required for vegetated roofs.