Drinking water regulations focus on the water coming out of the water treatment plant, not on the water that comes out of the taps in your home or office. Building (i.e., in-premise) plumbing systems deliver potable water to the tap, shower, and other fixtures. These plumbing systems are a critical component of the built environment because they represent front line human exposure to waterborne microbes, whether harmless or harmful, which can occur via aerosol inhalation, aspiration, skin contact, or ingestion. Funds from this grant support a series of studies by Amy Pruden and Marc Edwards to develop new knowledge about how design, operational parameters, and engineering interventions shape the premise plumbing microbiome in conventional and green buildings. Pruden and Edwards have four objectives: Evaluate the role of water stagnation time in shaping the premise plumbing microbiome and propensity for opportunistic premise plumbing pathogens to colonize; Characterize the resilience of the microbiome to heat shock or heat interruption and quantify the response of opportunistic premise plumbing pathogens (OPPPs); Resolve the effect of copper and chloramine disinfectants; and Identify key microbial ecological relationships among OPPPs and the broader premise plumbing microbiome, when subject to a range of engineering design and control measures. Pruden and Edwards plan to share their findings through peer-reviewed papers and presentations at national and international conferences, as well as through a webinar for building and water professionals. Additional grant funds support training for at least three graduate students.