Septic suitability in Caddo County, OK
Very limited
Caddo County, OK's SSURGO dominant class comes back "Very limited", covering 71.9% of the county. Practically, that rules out a simple gravity system for most of the county - 71.9% of it sits in USDA's most-constrained bucket. The county spans 1,277.754 square miles, home to 26,337 people.
What this number does and doesn't tell you
Two lots a mile apart in Caddo County can carry different soil, even though they share one countywide rating. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Caddo County: conventional vs. engineered cost
71.9% of Caddo County carrying a "Very limited" reading changes the realistic budget here. 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 Caddo County, OK compares
Among the 3,058 rated counties on this site, Caddo County, OK ranks 2,405 most-constrained nationally, and 62 of 77 within Oklahoma.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems