The national occurrence of perchlorate in drinking water was analyzed and mapped by compiling data from existing perchlorate occurrence surveys. The existing surveys included studies conducted by utilities for the first Unregulated Contaminant Monitoring Rule and by the states of Arizona, California, Massachusetts, and Texas. Perchlorate was detected in 26 states, Puerto Rico, and the Mariana Islands and was found in at least one source of approximately 5% of the nation—s large (> 10,000 population) public water systems. When found, perchlorate was typically present at concentrations of < 12 μg/L. Some water utilities that detected perchlorate have discontinued the use of perchlorate‐contaminated sources. On the basis of the results of a 2007 phone survey, it is estimated that at least 50 mgd of potable water production has been taken off line as a result of perchlorate contamination.

The US Environmental Protection Agency (EPA) is the lead federal agency for the security of drinking water in the United States. The agency is responsible for providing information and technical assistance to the more than 50,000 water utilities across the country. The distributed physical layout of drinking-water utilities makes them inherently vulnerable to contamination incidents caused by terrorists. To counter this threat, the EPA is using operations research to design, test, and deploy contamination warning systems (CWSs) that rapidly detect the presence of contaminants in drinking water. We developed a software tool to optimize the design process, published a decision-making process to assist utilities in applying the tool, pilot-tested the tool on nine large water utilities, and provided training and technical assistance to a larger group of utilities. We formed a collaborative team of industry, academia, and government to critique our approach and share CWS deployment experiences. Our work has demonstrated that a CWS is a cost-effective, timely, and capable method of detecting a broad range of contaminants. Widespread application of these new systems will significantly reduce the risks associated with catastrophic contamination incidents: the median estimated fatalities reduction for the nine utilities already studied is 48 percent; the corresponding economic-impact reduction is over $19 billion. Because of this operations research program, online monitoring programs, such as a CWS, are now the accepted technology for reducing contamination risks in drinking water.

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A blind interlaboratory study of radium‐226 (Ra‐226), radium‐228 (Ra‐228), and gross alpha and beta activity was conducted among five multistate certified laboratories to examine concerns regarding analytical variability for compliance with the revised Radionuclides Rule. Results of the interlaboratory study demonstrated that although Ra‐226 and gross beta measurements appeared to be both accurate and precise, even at low levels, Ra‐228 and gross alpha measurements were much less robust both within and among laboratories, which could result in potentially incorrect compliance decisions. There are several steps that utilities can take to improve reliability of compliance data, including mandating specific quality control (QC) steps by laboratories and ensuring that they follow the QC guidance in the US Environmental Protection Agency's laboratory certification manual and the Multi‐Agency Radiological Laboratory Analytical Protocols Manual, even though these may not always be enforced by laboratory certification authorities.

This article highlights the Threat Ensemble Vulnerability Assessment (TEVA) Research Program, established in 2003 by the U.S. Environmental Protection Agency's National Homeland Security Research Center to field questions concerning contamination warning systems (CWS) that are being developed by many water utilities. The article describes the partnership formed between the AWWA Water Utility Users Group and the TEVA Research Program to share information, data, and operational experiences. The article discusses two software tools that were developed and pilot‐tested through this partnership: TEVA‐SPOT (sensor placement optimization tool), a tool to identify the placement of optimal sensor locations, and CANARY, a tool to identify potential contamination incidents using real‐time water quality monitoring data.