National Estimate of Waterborne Disease Associated with Public Drinking Water

2006 National Estimate

In response to the Safe Drinking Water Act Amendments of 1996, the U.S. Environmental Protection Agency and CDC completed a series of epidemiologic studies and a national workshop that were designed to assess the magnitude of endemic waterborne acute gastrointestinal illness (AGI) associated with consumption of public drinking water. A joint report on the results of these studies is available at the EPA's Waterborne Disease Research Summaries. The report includes several papers discussing different methodologies for estimating the number of endemic waterborne AGI cases associated with public drinking water systems in the United States. In particular, the authors of two papers used current data and made various assumptions for missing data to derive overlapping estimates of:

1. 4.26–11.69 million annual AGI cases (confidence interval unknown) ¹, and
2. A mean of 16.4 million annual AGI cases (range 5.47–32.80) ².

These estimates should be interpreted with the understanding that information about endemic waterborne disease risks is imprecise and important data gaps remain. The relatively wide ranges of the estimates suggest a high level of uncertainty. Nevertheless, workshop participants agreed that enough data were available for rough estimates and that these estimates should be made at this time, with all assumptions and limitations fully described, so that others can evaluate the approaches.

These estimates, however, only describe a portion of the annual incidence of endemic waterborne-disease cases. To describe the overall incidence, estimates also would need to include the number of cases of waterborne disease other than AGI and the number of cases associated with nonpublic drinking water systems, commercially bottled water, recreational water, and water not intended for drinking. If these other types and sources of waterborne disease were considered, the estimated number of cases of endemic waterborne disease would be greater than the figures presented above.

1. Colford JM, Roy SL, Beach MJ, Hightower A, Shaw SE, Wade TJ. A review of household drinking water intervention trials and an approach to the estimation of endemic waterborne gastroenteritis in the United States. Journal of Water and Health 2006;4(Suppl 2):71-88.
2. Messner M, Shaw S, Regli S, Rotert K, Blank V, Soller J. An approach for developing a national estimate of waterborne disease due to drinking water and a national estimate model application. Journal of Water and Health 2006;4(Suppl 2):201-40.