Source: Water Resources Research
Water quality standards are not consistently observed by water utility companies. Using data from the United States Environmental Protection Agency, Elbakidze and Beeson  examined how differences in Clean Water Act regulations across American states affect compliance. They found that regulatory violations increased when additional state water quality standards were introduced, but one year after a new standard is implemented, cumulative violations seem to decline relative to the number of violations before introducing additional regulations. This suggests that compliance may improve after introducing new standards as operations and procedures are modified, the use of inputs like disinfectants is adjusted, or technologies are upgraded in response to new standards.
Citation: Elbakidze, L., & Beeson, Q. . State regulatory heterogeneity and compliance with the clean water and safe drinking water acts. Water Resources Research, 57, e2020WR028952. https://doi.org/10.1029/2020WR028952
—Jim Hall, Editor, Water Resources Research