Saving water--but at what cost?

Abstract

Strategies to reduce water consumption in buildings may have some unintended consequences. Rainwater cisterns, solar water heaters, and other similar efforts minimize potable water use and reduce energy consumption, but they may also degrade water quality. In a survey of buildings with various green infrastructure, Rhoads et al. found that water age, which affects residual chlorine levels, pipe corrosion, and even taste, was significantly greater than that in a conventional home. Consistent with those findings, there were also orders of magnitude more opportunistic pathogens such as Legionella species in the green plumbing systems. Reducing water age by eliminating unnecessary storage and regularly flushing pipes may help green water efforts become more widely adopted.