Brooke County, WV: the USDA septic-suitability picture
Very limited
Brooke County, WV: USDA's soil survey calls 67.5% of the county "Very limited" for a septic leach field. A standard gravity system routinely fails on ground like this; the same share of the county falls in USDA's worst absorption-field bucket outright. For scale: 89.036 square miles and 21,285 people call Brooke County home.
Before you rely on this for one lot
Two lots a mile apart in Brooke 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 Brooke County, WV
Brooke 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.
How Brooke County, WV compares
Among the 3,058 rated counties on this site, Brooke County, WV ranks 2,549 most-constrained nationally, and 55 of 55 within West Virginia.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems