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.

Compliance with recently proposed maximum contaminant levels for radon is likely to involve a significant expenditure for the US public water supply industry. More than 30,000 utilities are expected to find that their groundwater supplies exceed the proposed limit of 300 pCi/L. The authors of this article have estimated that the costs of installing and operating radon removal technologies across the United States will amount to $2.5 billion/year, with more than two thirds of those costs being borne by the very small water systems that serve 500 or fewer people.

The federal Safe Drinking Water Act (SDWA), as amended in 1996, enables benefit-cost analysis (BCA) to be used in setting federal drinking water standards, known as MCLs. While BCAs are typically conceived of as a tool to inform efficiency considerations by helping to identify MCL options that maximize net social benefits, in this paper we also illustrate how important equity and affordability considerations can be brought to light by suitably applying BCAs to drinking water regulations, especially in the context of communities served by relatively small water systems. We examine the applicability and relevance of health-health analysis (HHA), and provide an empirical evaluation of the risk tradeoffs that may be associated with the MCL established for arsenic. We find that the cost-associated risks may offset a nontrivial portion of the cancer risk reduction benefits attributed to the MCL (e.g., the additional adverse health impacts from the costs may be roughly half as large as the number of cancer cases avoided). This reveals the relevance of using the HHA approach for examining net benefits of MCLs in small drinking water utilities, and raises issues related to whether and how these cost-associated health risks should be considered in BCAs for drinking water standards.

Community water is a key place Americans will personally experience climate change. A 2013 nationally representative survey found that 92% of Americans want their community water provider to be a leader in preparing their community for climate change, and that community water providers are highly trusted sources for climate information. These findings place water utility professionals on the front line of climate response. A 2016 follow-up survey asked approximately 250 water professionals if and where they are using climate projection and assessment information, what analytic techniques they use where climate information is an input, what are their primary climate information sources, and whether they have the education and support materials needed to gather, use, and share climate information in complex decision making across job responsibilities and with external audiences. Survey findings include that over half of respondents are using climate projection and assessment information today and almost a quarter more will be using it in the next 5 years; use occurs in a wide range of job responsibilities; over 70% of respondents want to be a leader/team player in applying or sharing climate information; and over half of respondents self-identify the need for additional educational, training, and support materials. The survey findings provide a data-based contribution to understanding the opportunities and needs of water professionals as they prepare their communities for changes in the climate and water.

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