Physical, Chemical, and Microbiological Water Quality Variation between City and Building and within Multistory Building

Municipal drinking water entering buildings can experience degraded water quality due to in-building water treatment devices, plumbing design, materials, and occupancy patterns. To understand water quality patterns, we installed online sensors and collected grab samples throughout a multistory university building to quantify temporal and spatial fluctuations in temperature, pH, free chlorine, dissolved copper, trihalomethanes (THMs), cellular adenosine triphosphate (cATP), and organic matter surrogate (UV254). A whole-building water softener had a detrimental impact on water quality, increasing pH, decreasing disinfectant residual, and increasing THMs. Disinfectant residual was always greatest at the building inlet, with little to no measurable free chlorine at sinks and water fountains. Cellular adenosine triphosphate levels were lowest at the building inlet and measured greater at water fountains. Copper levels were <0.2 mg/L entering the building but ranged from 0.5 to 1.5 mg/L within the building. HVAC operations resulted in less variability for in-building water temperature than at the water treatment plant with temperatures averaging 5 degrees C warmer inside the building than at the building inlet. Trihalomethane concentrations were influenced by chlorine residual, pH, and water demand, with consistently higher in-building measurements than at the building inlet. Trihalomethane speciation remained constant throughout the study with chloroform being the greatest contributor to speciation, followed by dichlorobromoform, dibromochloromethane, and finally bromoform.

Automated summary

Water quality in buildings is influenced by in-building water treatment devices, with softeners having a detrimental impact on pH, disinfectant residual, and trihalomethane concentrations. Disinfectant residual is highest at the building inlet, with sinks and fountains having little to no measurable free chlorine. Copper levels fluctuate within the building, and HVAC operations result in higher in-building water temperatures compared to the building inlet.