Bivariate representation of population density using public and private drinking and wastewater infrastructure

Abstract. Drinking and wastewater infrastructure consists of both public and private usage. On each property parcel, drinking water can be privately provided by a well or publicly provided through a municipality. Wastewater can be a private septic tank or a public sewer. Property parcels can use all private, all public, or a combination of public and private solutions. It is important for planners and city officials to have knowledge of these systems, and it is also important to know the number of people using each type of infrastructure to prioritize resources and plan for future expansions. Visualizing the complexity of these data using separate univariate maps is aesthetically inferior involving back and forth comparisons. Further, the univariate maps represent land parcels only and do not capture the population that is using each type of water infrastructure. Our research develops a single bivariate map that facilitates the visualization of population using both public and private drinking and wastewater solutions simultaneously. The bivariate map is tended for use by planners, city officials, environmentalists, and others interested in the visualization of the spatial patterns of water infrastructure within one complete map.