Since the events of Sept. 11, 2001, the world has become a different place. More attention than ever is being paid to the nation's vulnerabilities, and this has prompted officials at all levels to examine the tools available for ensuring the security of public utilities. The recent emphasis on making sure that public water supplies are safe has created the need for continuous monitoring systems and analytical techniques that can be used at the utility level to test for a variety of toxic materials in a short amount of time. States and colleagues provide a survey of continuous monitoring and analytical methods currently available to utilities for security purposes. This survey grew out of an investigation the Pittsburgh (Pa.) Water & Sewer Authority (PWSA) and the University of Pittsburgh School of Engineering conducted in order to identify feasible analytical responses to security concerns. This investigation included a literature search; discussions with personnel from various water utilities, water industry organizations, and regulatory agencies; and evaluation of several commercially available monitoring and analytical systems. The article also takes a look at the analytical measures PWSA uses to screen for possible contamination in response to threats or suspected tampering with its water system as well as during times of heightened security. Although these methods are limited and their results should be interpreted with caution, there are some techniques, such as acute toxicity testing, that can be useful.

The events of Sept. 11, 2001, forever changed the climate of the United States and exposed the nation's vulnerabilities. In response, the U.S. Environmental Protection Agency (USEPA) prepared detailed guidance for drinking water utilities to follow in cases of suspected or actual incidents of intentional contamination of public water systems. Under the USEPA protocol, water utility personnel, as the authority onsite, would conduct an initial investigation or site characterization. Key to this preliminary assessment is the use of rapid analytical techniques for field screening. The Pittsburgh, Pennsylvania Water and Sewer Authority and the University of Pittsburgh School of Engineering evaluated a number of analytical methods that utility staff or emergency response teams could use to generate preliminary data during the site characterization phase. The technologies included rapid immunoassays, rapid enzyme tests, rapid polymerase chain reaction methods, field‐deployable gas chromatography‐ mass spectrometry, and acute toxicity screening. Research results indicated that, although analytical capabilities are rapidly improving, field‐screening technologies are not a substitute for standard laboratory analyses and the data such technologies provide should be considered presumptive. The rapid analytical techniques currently available can aid in assessing hazards and directing appropriate operational and public health responses. However, additional studies are needed to determine matrix effects, the influence of interferences, the incidence of inaccurate results, and the limitations of detection capabilities.

In an effort to better control formation of disinfection by‐products (DBPs), the US Environmental Protection Agency's recently promulgated Disinfectants/DBP Rule requires that US surface water treatment plants whose influent and effluent waters meet certain criteria practice enhanced coagulation. Although this treatment technique has been shown to effectively reduce natural organic matter, and consequently DBPs, questions have been raised concerning its effect on other aspects of water treatment such as particle and pathogen removal. The current study was designed to investigate the influence of decreased coagulation pH levels (an integral component of enhanced coagulation) on removal of Cryptosporidium oocysts as well as on reduction of total organic carbon (TOC), turbidity, and particle counts. A series of pilot‐plant trials was conducted in which commonly used coagulants (ferric chloride, alum, and polyaluminum chloride) were used at various pH levels to treat river water spiked with large numbers of Cryptosporidium oocysts. The results showed that TOC removal is significantly enhanced by coagulation at lower pH levels and that all three coagulants are effective in removing Cryptosporidium oocysts during conventional treatment (mean removal = 4.3 log units). However, turbidity and particle counts appear to be unreliable indicators of oocyst removal. Finally, the investigation suggested that lowering coagulation pH does not interfere with removal of Cryptosporidium. However, questions remain concerning the use of alum at pH 5.

To preserve the parklike appearance of an open finished water reservoir and meet a state mandate for increased protection of stored finished water, the Pittsburgh Water and Sewer Authority investigated postreservoir treatment options. Faced with a state mandate to cover a 125‐mil‐gal‐ (0.4 × 106–m3‐) capacity finished water reservoir and with public opposition to using a floating cover, the Pittsburgh Water and Sewer Authority explored the possibility of postreservoir treatment options. The regulatory agency indicated that any acceptable posttreatment must ensure 4‐log reduction of viruses, 3‐log reduction of Giardia, and 2‐log reduction of Cryptosporidium. The authority studied ozonation and membrane filtration for this application. Ozone inactivation trials resulted in a 1.0‐ to 1.2‐log inactivation of Cryptosporidium oocysts at bench scale and 0.1‐ to 0.5‐log inactivation at pilot scale. Membrane filter challenge studies demonstrated a 5‐log removal of Giardia cysts and 6‐log removal of Cryptosporidium oocysts. Based on the results of pilot testing and additional considerations, the authority is constructing a 20‐mgd (0.07 × 106–m3/d) microfiltration plant to treat water leaving the finished water reservoir.