AWWA WSC63708

While drinking water system security has always been an important issue for U.S. water treatment facilities, it has become key in the country's domestic security response to the catastrophic events of September 11, 2001 that framed the U.S. as a terrorist target. Online monitoring of drinking water distribution systems offers potential in eliminating the danger of purposeful contamination that would, otherwise, be evident only through symptomatic events in the community served by the water system. Seven credible drinking water chemical contaminants (aldicarb, cycloheximide, dicrotophos, nicotine, sodium arsenate, sodium cyanide, and sodium fluoroacetate) were measured at different dosing concentrations to determine their detectability in a drinking water distribution system model. These contaminants were monitored by measuring common water quality parameters such as conductivity, pH, chlorine residual, turbidity, total organic carbon (TOC), and UV254 as indicator analytes. This study included: establishing a baseline for each water quality parameter; determining laboratory instrument response to various concentrations of contaminant mixed with treated drinking water in benchtop containers; using benchtop data to introduce appropriate contaminant concentrations into a benchscale distribution system monitored by commercially available on-line water quality instruments; and, determining detectability of specified contaminant concentrations in the bench-scale distribution system. Results indicate that the seven chemical contaminants can be detected at relatively low concentrations with routine monitoring. Some of the seven chemical contaminants can be detected below a concentration that will cause significant health impacts. Includes 11 references, tables, figures.