AWWA JAW59537

Evaluations of the costs and benefits of US drinking water standards typically consider only a single contaminant or class of contaminants. However, the US Environmental Protection Agency (USEPA) is in the process of formulating and implementing multiple new regulations, and drinking water systems will be expected to comply with all of them simultaneously. The joint effects of different regulations are not necessarily the sum of the effects of the individual regulations. In some cases, treating for one contaminant may remove other contaminants. In other instances, treating for one contaminant (e.g., pathogens) may make it more difficult to comply with regulations for other contaminants (e.g., disinfection byproducts). A simulation model was developed to assess the national costs and benefits of compliance with multiple drinking water standards. For each of the approximately 55,000 US community water systems, concentrations of raw water constituents, treatment type, and removal efficiencies were sampled from statistical models and used to compute finished water concentrations. Modeling the effects of different regulations at the same time and using the same modeling assumptions allowed the cost-effectiveness of alternative regulations to be compared on an equal basis. For example, this study found that the revised arsenic maximum contaminant level (MCL) is more cost-effective than the uranium MCL at reducing cancer risk. By facilitating more direct comparison of the cost-effectiveness of different regulations, an integrated model can help utilities prioritize their regulatory options. In addition, a better understanding of the joint effects of different regulations may help USEPA and other stakeholders to design more effective overall regulatory programs. Includes 55 references, tables, figures.