Cost to utilities of a lower MCL for arsenic

Abstract

Water utilities need to begin now to evaluate their costs for complying with a lower MCL for arsenic.Compliance with a revised arsenic maximum contaminant level (MCL) for drinking water will require a substantial cost to water suppliers in the United States. A rigorous methodology was developed to estimate the national cost of complying with alternative regulatory limits for arsenic. This methodology considered the feasibility of available technologies based on existing treatment at utilities that are not in compliance and the level of water quality constituents that limit technology performance. A least‐cost method of selecting treatment alternatives was used to estimate compliance costs and the results were extrapolated nationally. Estimated national compliance costs ranged from $330 million per year for a 20‐μg/L MCL to more than $4.1 billion/year for a 2‐μg/L MCL. These estimates represent a 10‐ to 20‐fold increase in the US Environmental Protection Agency's (USEPA's) preliminary cost estimates. Although the effect on small systems would be substantial, this study found that the cost burden would be shared equally between small (<10,000 people served) and large (>10,000 people served) systems. USEPA also found that systems using groundwater would bear more of the total costs (62 to 82 percent) than systems using surface water.