A public health perspective on onsite wastewater systems.


I ssues related to onsite wastewater systems are frequently among the top concerns of environmental health practitioners. Demographic, infrastructure, and land use trends show a likely continuation of this concern in the near future. Although the proportion of housing units with onsite systems has remained relatively constant in the United States over the last 30 years, at approximately 25 percent, about one-third of new homes are connected to onsite systems. Rapid growth of rural and suburban fringe areas in some regions has led to more construction using onsite systems in higher-density areas. Although sewers may be feasible in some of these areas, onsite systems are often installed for new homes because infrastructure cannot always keep up with housing demand. Although the issue has not been specifically studied, concerns have been raised that a shift in the built environment from centralized sewer systems to onsite systems could potentially increase population exposure to wastewater contaminants. In fact, although many of the practitioners who deal with onsite wastewater issues on a daily basis are in the field of public health, the body of literature on the public health effects of onsite systems is relatively small. Much of the literature about onsite systems is based in environmental engineering and soil science because these fields are closely involved in the design and construction of these systems. Health issues may arise, however, if onsite systems are improperly sited, designed, installed, or operated. A recent literature review by CDC found a limited number of outbreak investigations and epidemiological studies implicating problematic onsite systems as causes of disease. Although the relatively small number of studies limits analysis, some emerging trends indicate that the following factors have been associated with outbreaks related to onsite systems: • intermittent use of drinking-water and wastewater systems, as in recreational settings or large temporary gatherings (e.g., fairs); • installation of onsite systems in soil and geologic environments that are unsuitable (e.g., installation associated with a recent gastroenteritis outbreak in Ohio—see www.cdc.gov/nceh/ehs/Docs/NCEH_ South_Bass_Island_Final_Report.pdf); and • extreme precipitation events such as those linked to hurricanes or other large storms. These results suggest that design criteria for onsite systems should include factors such as intermittent use and extreme storm events. The existing published literature is insufficient to allow this conclusion to be stated with certainty, but further investigation appears worthwhile. In addition, the public health effects from onsite systems may not be limited to actual illness but probably also include exposure to wastewater pathogens. An epidemiologic study in Canada found that people whose septic systems were sited closer to their wells exA Public Health Perspective on Onsite Wastewater Systems CDR Richard J. Gelting, Ph.D., P.E. Direct from CDC’s Environmental Health Services Branch

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@article{Gelting2007APH, title={A public health perspective on onsite wastewater systems.}, author={Richard J Gelting}, journal={Journal of environmental health}, year={2007}, volume={69 7}, pages={62-3} }