Septic suitability in Louisa County, IA
Very limited
Louisa County, IA: USDA's soil survey calls 94.9% of the county "Very limited" for a septic leach field. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 94.9% of Louisa County's land. The county spans 401.777 square miles, home to 10,630 people.
What this number does and doesn't tell you
USDA's survey covers the whole of Louisa County, IA at once, not any single address. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Louisa County: conventional vs. engineered cost
94.9% of Louisa 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, Louisa County, IA ranks 681 most-constrained nationally, and 47 of 99 within Iowa.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems