Mercer County, MO's soil, for a septic absorption field

Very limited

Soil across 99.3% of Mercer County, MO rates "Very limited" in USDA's septic-absorption-field interpretation. Practically, that rules out a simple gravity system for most of the county - 99.3% of it sits in USDA's most-constrained bucket. Mercer County, MO is 453.835 square miles with a population of 3,452.

What Mercer County's reading doesn't cover

Two lots a mile apart in Mercer County can carry different soil, even though they share one countywide rating. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Mercer County will actually do.

What a system would cost here

With 99.3% of Mercer County rating "Very limited", a standard gravity system is not a safe assumption here. 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, Mercer County, MO is the 58-most-constrained of 3,058 rated counties for septic soil. Within Missouri alone it ranks 11 of 114.

Before you act on this

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