Septic soil in Adams County, IA, by the numbers

Very limited

Soil across 95.7% of Adams County, IA rates "Very limited" in USDA's septic-absorption-field interpretation. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 95.7% of Adams County's land. Adams County covers 423.433 square miles and counts 3,606 residents.

This is a county figure, not a parcel figure

Adams County's rating is an average across the whole county, not a promise about any one lot inside it. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Adams County.

System cost, conventional vs. engineered

Given Adams County's rating, plan for the engineered-system range rather than the conventional one. The engineered-system range, $10,000-$40,000 (mound or aerobic treatment), is the more realistic number to plan around, against $3,000-$8,000 for a conventional system on the rare lot that passes.

Where this sits nationally

Nationally, Adams County, IA is the 574-most-constrained of 3,058 rated counties for septic soil. Within Iowa alone it ranks 44 of 99.

Further reading

How this rating is built, and its real limits · Conventional vs. engineered septic systems