COST TO UTILITIES OF 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 t he United States. A rigorous methodology was developed to estimate the national cost of complying with alternative regulatory limits for ars enic. This methodology considered the feasibility of available technol ogies based on existing treatment at utilities that are not in complia nce and the level of water quality constituents that limit technology performance. A least-cost method of selecting treatment alternatives w as used to estimate compliance costs and the results were extrapolated nationally. Estimated national compliance costs ranged from $330 mill ion per year for a 20-mu g/L MCL to more than $4.1 billion/year for a 2-mu g/L MCL. These estimates represent a 10- to 20-fold increase in t he US Environmental Protection Agency's (USEPA's) preliminary cost est imates. Although the effect on small systems would be substantial, thi s study found that the cost burden would be shared equally between sma ll (<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.