Hydraulic Models of Buildings for Use in Contamination Studies

Though hydraulic models are widely used to simulate contamination events in drinking water distribution systems, the use of similar tools to study the movement of contaminants within buildings is very limited. This paper describes the use of standard EPANET models of selected residential and commercial building types to assess their vulnerability to contamination of the drinking water supply resulting from events occurring within the distribution system feeding the buildings or from within the building itself. This analysis is applicable to either accidental contamination events such as cross connections within the building or intentional contamination events. Hydraulic models representing a typical high rise building and a single-family residence were constructed. The residential model includes all piping in both the cold water system and the hot water system. The high rise model includes the pumping system, tanks, check valves, major vertical backbone piping and a skeletonized representation of the delivery pipes on each floor. Both models are applied in extended period simulations and the movements of both internally and externally generated contaminants are traced through the buildings. Issues that are discussed include: representation of demands, level of skeletonization, operating rules, hydraulic and water quality time steps, potential contamination of the distribution system itself, and future applications of high resolution hydraulic models for human exposure assessments.