Several research and evaluation studies were performed on alternative onsite systems on sites with severe limitations for conventional systems. The major limitations included slow permeability, a seasonally high water table, and limiting soil horizons. Several typical site evaluation techniques were also evaluated, and groundwater contamination was investigated. The studies evaluated systems that rely on the soil for treatment and disposal (including Low Pressure Pipe, alternating soil absorption fields, shallow conventional trenches, gravelless trenches, and mounds) and systems that discharge to surface waters or to the atmosphere (including intermittent sand filters, upflow gravel filters, subsurface gravel beds, and evapotranspiration beds). Studies were performed on full-scale operating systems, scaled-down field systems, or laboratory columns. Alternating soil absorption systems (ASAS) could not be evaluated in these studies, but the use of shallow ASASs could potentially be highly successful. Intermittent sand filters preceded by a septic tank and followed by disinfection, as required, had the highest potential for success for surface discharge.