Ontario County, NY: the USDA septic-suitability picture

Very limited

Ontario County, NY's SSURGO dominant class comes back "Very limited", covering 83.6% of the county. A standard gravity system routinely fails on ground like this; the same share of the county falls in USDA's worst absorption-field bucket outright. For scale: 644.025 square miles and 113,012 people call Ontario County home.

Before you rely on this for one lot

This is a countywide, area-weighted figure across every soil survey map unit in Ontario County, NY - never a reading for one specific parcel. The real answer for one lot is still a site-specific perc test, running about $750-$1,850 (typically near $1,300).

Budgeting for a system in Ontario County, NY

Ontario County's soil reading pushes the likely outcome toward an engineered system rather than a conventional one. 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.

Ontario County's rank among New York counties

Among the 3,058 rated counties on this site, Ontario County, NY ranks 1,813 most-constrained nationally, and 47 of 61 within New York.

Further reading

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