Philadelphia County, PA: no USDA soil-survey match

Unrated

The dominant soil here (often already-developed urban land) carries no septic-suitability interpretation from USDA - too rare a gap to guess at. A local percolation test is the only way to know. Philadelphia County, PA covers 134.325 square miles and is home to 1,573,916 people, but the dominant soil here carries no SSURGO absorption-field interpretation to report.

This is a county figure, not a parcel figure

Two lots a mile apart in Philadelphia County can carry different soil, even though they share one countywide rating. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Philadelphia County.

System cost, conventional vs. engineered

Philadelphia County carries no dominant soil rating, so there's no shortcut here - it comes down entirely to the site-specific test. Nationally, conventional systems run $3,000-$8,000 and engineered alternatives run $10,000-$40,000 - which one applies to a lot in Philadelphia County is exactly what a perc test settles.

Further reading

How this rating is built, and its real limits · What to check before buying rural land on septic