Septic soil in Rockingham County, VA, by the numbers
Very limited
Soil across 80.9% of Rockingham County, VA rates "Very limited" in USDA's septic-absorption-field interpretation. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 80.9% of Rockingham County's land. Rockingham County, VA is 849.796 square miles with a population of 87,674.
What Rockingham County's reading doesn't cover
Rockingham County's rating is an average across the whole county, not a promise about any one lot inside it. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Rockingham County will actually do.
What a system would cost here
With 80.9% of Rockingham 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.
Rockingham County's rank among Virginia counties
Nationally, Rockingham County, VA is the 1,994-most-constrained of 3,058 rated counties for septic soil. Within Virginia alone it ranks 42 of 110.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems