Perc Testing

A perc test is a soils test to determine if the soils and groundwater conditions on a property are suitable for use as an on-site sewage disposal system. All properties not served by public water and sewer must have this test before beginning construction of any structure with plumbing. If an area of acceptable soils is found, a plat is established of the area to be designated for sewage disposal. Perc tests are performed when contemplating new construction, adding on to land already served by on-site systems and when a system fails.

The health department conducts soil evaluations for the construction of residential and commercial septic systems. In addition, it also evaluates soil for replacement septic systems when the current septic systems fail. The application for a new construction perc test is located at the St. Mary’s County Department of Land Use and Growth Management and requires a fee. When a septic system fails, the health department receives applications for repair perc tests; there is no fee associated with this service.

For more information, please contact the health department at or call 301-475-4321.

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