Carroll County, TN Septic Rating
Carroll County, TN: the USDA septic-suitability picture
Very limited
USDA puts Carroll County, TN at "Very limited" for septic absorption fields, the dominant reading across 96.5% of the county's soil. This is the reading that pushes a project toward an engineered system rather than a conventional one, covering that same share of Carroll County's land. The county spans 598 square miles, home to 29,107 people.
What this number does and doesn't tell you
Nothing about Carroll County, TN's SSURGO figure applies to a specific address - it's a county-wide average. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Carroll County: conventional vs. engineered cost
96.5% of Carroll County carrying a "Very limited" reading changes the realistic budget here. Conventional systems run $3,000-$8,000 where they pass; where they don't, engineered alternatives (mound or aerobic treatment, whichever the health department requires) run $10,000-$40,000 - budget toward the higher figure until a perc test says otherwise.
Where this sits nationally
Among the 3,058 rated counties on this site, Carroll County, TN ranks 454 most-constrained nationally, and 4 of 95 within Tennessee.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems