The cost of providing safe reliable water services in the United States is increasing for utilities and their customers raising questions about the scale and scope of water affordability challenges. How we measure and understand water affordability is debated. Here we developed an open and repeatable approach that calculates five affordability metrics including a new metric that combines affordability prevalence and burden along a continuum. We calculated these metrics for multiple volumes of water usage (from 0 to 16000 gallons per month) using rate data available in 2020 at the scale of census block groups and service areas. We applied this approach to 1791 utilities in four states (California Pennsylvania North Carolina and Texas) which cumulatively serve 72 million persons. We found 77% of utilities had more than 20% of their population below 200% of the federal poverty level suggesting widespread poverty contributes to affordability challenges for many utilities. Minimum wage earners spend more than a day of labor per month to pay water bills for relatively low usage (4000 gallons per month) in 67% of utilities but upwards of 3 days of labor at higher volumes (12000 gallons per month) in 29% of utilities. Depending on how much water a household uses our results suggest a tenth to a third of households are working more than a day each month to afford their water bills. We developed an interactive data visualization tool to bring greater transparency to water affordability by allowing users to explore affordability at the block group and utility scale at different volumes of usage. The underlying data in the visualization tool can be expanded and updated over time further increasing the transparency and understanding of water affordability in the U.S.
