What Darke County, OH's soil rates for a septic system
Very limited
In Darke County, OH, 99.5% of the surveyed land carries a "Very limited" rating for a standard septic drain field. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 99.5% of Darke County's land. Darke County, OH is 598.102 square miles with a population of 51,462.
What Darke County's reading doesn't cover
This is a countywide, area-weighted figure across every soil survey map unit in Darke County, OH - never a reading for one specific parcel. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Darke County will actually do.
What a system would cost here
With 99.5% of Darke County rating "Very limited", a standard gravity system is not a safe assumption here. 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, Darke County, OH is the 20-most-constrained of 3,058 rated counties for septic soil. Within Ohio alone it ranks 3 of 87.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems