Henry County, OH: the USDA septic-suitability picture
Very limited
Henry County, OH's SSURGO dominant class comes back "Very limited", covering 99% of the county. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 99% of Henry County's land. For scale: 416.013 square miles and 27,536 people call Henry County home.
Before you rely on this for one lot
Two lots a mile apart in Henry County can carry different soil, even though they share one countywide rating. The real answer for one lot is still a site-specific perc test, running about $750-$1,850 (typically near $1,300).
Budgeting for a system in Henry County, OH
Henry County's soil reading pushes the likely outcome toward an engineered system rather than a conventional one. 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, Henry County, OH ranks 91 most-constrained nationally, and 14 of 87 within Ohio.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems