A site evaluation, also known as a soil test, is completed to determine the feasibility of a site for septic system design purposes. The feasibility of a site includes meeting minimum soil standards according to the Maine Subsurface Wastewater Disposal Rules. A perc test is a similar method used in other states to determine soil absorption rates for septic design purposes.

Soil characteristics are found by evaluating a soil test pit dug on-site. The texture of the soil and limiting factors such as depth to bedrock, hardpan, or groundwater are determined to size and set the elevation of the planned disposal field.

Site features such as lot size, slope, and setback distances to wells, surface waters, dwellings, property lines, etc. are also considered to locate a disposal field, and choose a system type.