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Current attempts to establish causal links betweenadverse health effects and the concentrations ofdisinfection byproducts (DBPs) in drinking waterare based on infrequent measurements at the point ofentry (POE) to, and a few points in, the distributionsystem. In this article the authors demonstrate that achloraminated distribution system can be sampledrelatively simply to obtain the median concentrationsof DBPs in the tap water of a large population servedby a single supply.The authors report that considerable short-termtemporal variability in the DBP levels (measured interms of trihalomethanes, haloacetic acids, and totalorganic halide) at the POE to a chloraminated distributionsystem appears to be related to the control of theaddition of ammonia at the treatment plant. Samplescollected every few hours over several consecutive daysfrom the POE and from several distribution systempoints showed that this temporal variability at the POEmost likely was dampened in the distribution systemdue to a combination of innate storage within the systemand dynamic mixing behavior induced by variationsin flow and demand.Although the variations in measured DBP concentrationsin the system were relatively small and appear tobe normally distributed, the variations in measuredDBP concentrations at the POE were much larger. Thissuggests that more accurate characterization of weeklyDBP concentrations throughout the chloraminateddistribution system for purposes of exposure assessmentcan be obtained from the analysis of a singledaytime-collected grab sample at a representative pointin the distribution system rather than from the POE tothe distribution system. Includes 25 references, tables, figures.

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Edition: Vol. 96 - No. 11 Published: 11/01/2004 Number of Pages: 12File Size: 1 file , 550 KB