Washington County, CO's soil, for a septic absorption field

Somewhat limited

Soil across 55.6% of Washington County, CO rates "Somewhat limited" in USDA's septic-absorption-field interpretation. That's a middle reading: not the outright failure "very limited" soil produces, but not a clean pass either. Design changes often bridge the gap. Washington County covers 2,518.084 square miles and counts 4,771 residents.

This is a county figure, not a parcel figure

Nothing about Washington County, CO's SSURGO figure applies to a specific address - it's a county-wide average. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Washington County.

System cost, conventional vs. engineered

Given Washington 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.

How Washington County, CO compares

Nationally, Washington County, CO is the 2,973-most-constrained of 3,058 rated counties for septic soil. Within Colorado alone it ranks 61 of 63.

Related guides

How this rating is built, and its real limits · How a percolation test actually works