Assessment of contaminants in California drinking water by region and system size

Abstract

Abstract In this California‐wide spatial analysis, a cumulative ranking method and a trend test were used to estimate and compare concentrations of 12 contaminants and two drinking water standard violations by system size and region. The San Joaquin Valley, areas not served by water systems, and small water systems (less than 200 connections) had the highest cumulative rank with many high levels of contaminants. Large systems and the South Coast had the highest levels of disinfection byproducts and industrial contaminants. Based on a trend analysis, violations and concentrations of arsenic and cadmium decreased as system size increased, while industrial contaminant concentrations and disinfection byproducts increased as system size increased ( p < .05). Although not indicative of violating drinking water standards, this study's results demonstrate where efforts to address specific contaminants can be targeted by region or system type. The results can help elucidate where contaminants may be elevated, from both an individual and multiple‐contaminant perspective.