The inequity of the Revised Arsenic Rule for very small community drinking water systems

The U.S. Environmental Protection Agency (EPA) recently reduced the maximum contaminant level for arsenic in community drinking water systems from 50 to 10 ppb. EPA uses net benefit analyses aggregated at the national-scale to set drinking water standards. Such aggregation may result in compliance options that are not cost-effective for very small systems, and may limit opportunities for these communities to receive variances. We completed a benefit-cost analysis and an affordability analysis of 14 tribal communities in Arizona to better understand the regulation's impact on very small water systems ranging from 6 to 95 service connections. Compliance alternatives included both technological and non-technological solutions. Health benefits were based on an EPA study of morbidity and mortality. The results show that all communities can comply with feasible alternatives; however, the tangible costs of the revised arsenic regulation far outweigh the expected health benefits and do not meet EPA's affordability criteria. The results support other studies that suggest a more equitable regulatory-setting process is needed to consider both health and economic impacts. Otherwise, the unintended result is a shifting of resources among risks instead of actual risk reduction.