Impact of Droughts on Served Drinking Water Disparities in California, 2007–2020.

This article examines the impact of drought on arsenic and nitrate concentrations in drinking water provided by community water systems (CWSs) in California, focusing on disparities across sociodemographic groups. Using data from 2,378 CWSs serving 34.8 million residents between 2007 and 2020, the study finds that drought conditions increase nitrate levels primarily in CWSs serving majority Latino/a communities, with the effect most pronounced in very small and privately owned systems and in surface water sources. Arsenic concentrations in surface water also rise during drought across all groups, while groundwater arsenic tends to decrease in majority Latino/a communities. These findings highlight the potential for climate-driven droughts to exacerbate existing drinking water quality disparities and underscore the need for targeted investments in drought resilience and equitable water infrastructure planning.