Using process models to estimate residential water use and population served

Abstract

A key measure of efficiency in the field of urban water demand is gallons per capita per day of water use. One popular metric, gross gallons per capita per day, can be misleading because it includes nonresidential water uses. As an alternative, this article addresses the calculation of residential water use defined as the product of population and per capita use associated solely with people who are physically present and using water in single‐family and multifamily residences at a given time. This approach allows for consistent benchmarking because per capita use multiplied by population yields the actual amount of water delivered to the residential sector. Process models for residential population and indoor and outdoor per capita water use can be used to estimate total residential water use if they incorporate the variability among fixture end uses and irrigable area for every household served by a utility. When this approach was applied to the Sanford, Fla., case study area, the process models predicted single‐ and multifamily water use with reasonable accuracy.