American Water Works Association v. EPA
United States Court of Appeals for the District of Columbia Circuit
40 F.3d 1266 (1994)
The EPA (defendant) determined that setting a maximum contaminant level (MCL) for lead was infeasible because lead mostly entered water through privately-owned plumbing outside its jurisdiction, testing produced widely inconsistent results, and aggressive corrosion controls to lower lead could increase other toxins, so the EPA instead required limited corrosion-control treatment techniques; environmental and water-industry groups (plaintiffs) challenged the decision, arguing an MCL was feasible.
Whether the Environmental Protection Agency can specify a water-treatment technique in lieu of a maximum contamination level if it is not economically or technologically feasible to determine the level of the particular contaminant in a public water system.