Madison County, TX: the USDA septic-suitability picture
Very limited
Madison County, TX's SSURGO dominant class comes back "Very limited", covering 95.6% of the county. That reading means a conventional system is a poor bet here - 95.6% of Madison County lands in the strictest "very limited" bucket USDA uses. The county spans 466.116 square miles, home to 13,877 people.
What this number does and doesn't tell you
Nothing about Madison 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.
Madison County: conventional vs. engineered cost
95.6% of Madison 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.
Madison County's rank among Texas counties
Among the 3,058 rated counties on this site, Madison County, TX ranks 584 most-constrained nationally, and 37 of 253 within Texas.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems