Septic Tank Density and Ground‐Water Contamination

Abstract

ABSTRACT As more and more cases of ground‐water contamination are reported, the public has become increasingly aware of the importance of preserving the quality of this limited resource, especially in areas totally dependent on ground‐water sources. Although most of the attention is focused on pollution by organic chemicals, these compounds are responsible for a relatively small percentage of ground‐water‐related disease outbreaks. The majority of waterborne disease outbreaks are caused by bacteria and viruses present in domestic sewage. Septic tanks contribute the largest volume of waste water, 800 billion gallons per year to the subsurface, and are the most frequently reported cause of ground‐water contamination associated with disease outbreaks. The U.S. Environmental Protection Agency has designated areas with septic tank densities of greater than 40 systems per mi 2 (1 system per 16 acres) as regions of potential ground‐water contamination. Numerous cases of ground‐water contamination have been reported in areas of high septic tank density; lot sizes in these areas range from less than one‐quarter acre to three acres. The single most important means of limiting ground‐water contamination by septic tanks is to restrict the density of these systems in an area.