Document Type

Technical Report

Publication Date



Surface water, drinking water, septic take absorption, watewater treatment


The failure of septic tanks in treatment of wastewater has been responsible for causing health hazards due to contamination and pollution of groundwater and surface waters used for drinking water supplies. Most of these failures have been in the absorption field. Little or no actual research has been performed to establish design criteria for septic tank absorption fields to be used by local, state or federal Health Agencies or Pollution Control Agencies. Historically, almost all design criteria has beed based on a percolation test and the number of bedrooms to be served. Both of these methods have repeatedly been shown to have little or no relationship to efficient absorption field performance. This study was conducted to test the theory that failures can be corrected with relatively inexpensive changes in absorption field design. Reported here are the results of an investigation of the septic tank effluent treatment capacity of gravel from local streams. The effluent was percolated through lysimeters containing various depths and sizes of gravel. The gravel was varied as to its physical characteristics, coefficient of uniformity and effective particle size as well as depth and size. The findings may lead to the modification of absorption fields for more efficient waste treatment.

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