Setting Drinking Water Standards: Historical Perspective and Simulation Modeling

• Main Author: Gurian, Patrick Lee
• Format: Others
• Published: Research Showcase @ CMU 2001
• Online Access: http://repository.cmu.edu/dissertations/662; http://repository.cmu.edu/cgi/viewcontent.cgi?article=1565&context=dissertations

Setting drinking water standards involves both technical knowledge and an understanding of societal values and institutions. To provide perspective and tools for evaluating these issues a set of historical and current regulatory assessments are presented here. The first of these case studies considers the history of the 1914 Public Health Service drinking water standards and is based on information in archival materials and journal articles of the time period. A simulation model to estimate the costs and benefits of proposed drinking water regulations on U.S. community water systems is then developed. The model simulates current contaminant concentrations and existing treatment types based on fitted statistical models. For systems that exceed any of the drinking water standards included in the model, the costs and effectiveness of alternative compliance strategies are simulated, and the system is assumed to select the least costly strategy capable of achieving compliance with the standards. This modeling approach allows for quantitative estimates of the uncertainty in regulatory impacts, geographic and size class specificity, and the consideration of multiple standards simultaneously. The model is applied first to the case of a lower drinking water standard for arsenic. The marginal cost-effectiveness of different standards and the impacts of several alternative regulatory approaches are considered. Discrepancies in previous estimates of compliance costs are shown to result primarily from differences in the treatment process cost estimates used by the different studies. An evaluation of alternative regulatory approaches for arsenic indicates that point-of-use treatment has the potential to be a lowcost means of compliance for smaller water systems but would most likely provide less uniform water quality than centralized treatment, with costs and performance highly dependent on the frequency of monitoring and service. The simulation model is then applied to consider jointly standards for three contaminants: arsenic, nitrate, and uranium. The costs and benefits of imposing the three standards simultaneously are smaller than the sum of the costs and benefits of the individual standards. For these contaminants the difference between the sum of the individual analyses and the integrated analysis is fairly small, but the effects of joint regulation may be larger for contaminants with more highly correlated occurrence distributions.