Fauquier County's SSURGO septic rating
Very limited
Fauquier County, VA's SSURGO dominant class comes back "Very limited", covering 82.2% of the county. Practically, that rules out a simple gravity system for most of the county - 82.2% of it sits in USDA's most-constrained bucket. For scale: 647.994 square miles and 75,865 people call Fauquier County home.
Before you rely on this for one lot
Fauquier County's rating is an average across the whole county, not a promise about any one lot inside it. 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 Fauquier County, VA
Fauquier 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, Fauquier County, VA ranks 1,915 most-constrained nationally, and 40 of 110 within Virginia.
Before you act on this
How this rating is built, and its real limits · Conventional vs. engineered septic systems