Polk County, IA's soil, for a septic absorption field

Very limited

In Polk County, IA, 63.6% of the surveyed land carries a "Very limited" rating for a standard septic drain field. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 63.6% of the county. Polk County, IA is 572.72 square miles with a population of 516,185.

What Polk County's reading doesn't cover

Nothing about Polk County, IA's SSURGO figure applies to a specific address - it's a county-wide average. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Polk County will actually do.

What a system would cost here

With 63.6% of Polk 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, Polk County, IA is the 2,642-most-constrained of 3,058 rated counties for septic soil. Within Iowa alone it ranks 97 of 99.

Before you act on this

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