Septic suitability in Oldham County, TX
Very limited
Oldham County, TX: USDA's soil survey calls 50.4% of the county "Very limited" for a septic leach field. Practically, that rules out a simple gravity system for most of the county - 50.4% of it sits in USDA's most-constrained bucket. The county spans 1,500.523 square miles, home to 1,823 people.
What this number does and doesn't tell you
Nothing about Oldham County, TX's SSURGO figure applies to a specific address - it's a county-wide average. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Oldham County: conventional vs. engineered cost
50.4% of Oldham 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.
Where this sits nationally
Among the 3,058 rated counties on this site, Oldham County, TX ranks 2,878 most-constrained nationally, and 230 of 253 within Texas.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems