What Plymouth County, MA's soil rates for a septic system

Very limited

84% of Plymouth County, MA's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. Practically, that rules out a simple gravity system for most of the county - 84% of it sits in USDA's most-constrained bucket. Plymouth County covers 658.521 square miles and counts 542,090 residents.

This is a county figure, not a parcel figure

This is a countywide, area-weighted figure across every soil survey map unit in Plymouth County, MA - never a reading for one specific parcel. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Plymouth County.

System cost, conventional vs. engineered

Given Plymouth 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.

Plymouth County's rank among Massachusetts counties

Nationally, Plymouth County, MA is the 1,774-most-constrained of 3,058 rated counties for septic soil. Within Massachusetts alone it ranks 6 of 14.

Related guides

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