Septic soil in Marion County, TN, by the numbers

Very limited

In Marion County, TN, 84.1% of the surveyed land carries a "Very limited" rating for a standard septic drain field. Practically, that rules out a simple gravity system for most of the county - 84.1% of it sits in USDA's most-constrained bucket. Marion County covers 498.254 square miles and counts 29,826 residents.

This is a county figure, not a parcel figure

USDA's survey covers the whole of Marion County, TN at once, not any single address. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Marion County.

System cost, conventional vs. engineered

Given Marion County's rating, plan for the engineered-system range rather than the conventional one. The engineered-system range, $10,000-$40,000 (mound or aerobic treatment), is the more realistic number to plan around, against $3,000-$8,000 for a conventional system on the rare lot that passes.

Where this sits nationally

Nationally, Marion County, TN is the 1,770-most-constrained of 3,058 rated counties for septic soil. Within Tennessee alone it ranks 38 of 95.

Before you act on this

How this rating is built, and its real limits · Conventional vs. engineered septic systems