"Graywater refers to the reuse of water drained from baths, showers, washing machines, and sinks ... for irrigation and other water conservation applications. Contrary to common belief, graywater is not a 'safe' product -- it contains bacteria and other potential pathogens. Consequently, the potential reuse of graywater is a public health issue, not a water conservation priority." Includes discussion of water quality issues for gray water and harvested rainwater. From Colorado State University Extension.