St. John the Baptist Parish, LA: the USDA septic-suitability picture

Very limited

St. John the Baptist Parish, LA: USDA's soil survey calls 58.2% of the county "Very limited" for a septic leach field. That reading means a conventional system is a poor bet here - 58.2% of St. John the Baptist Parish lands in the strictest "very limited" bucket USDA uses. For scale: 214.474 square miles and 39,694 people call St. John the Baptist Parish home.

Before you rely on this for one lot

USDA's survey covers the whole of St. John the Baptist Parish, LA at once, not any single address. 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 St. John the Baptist Parish, LA

St. John the Baptist Parish'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.

Where this sits nationally

Among the 3,058 rated counties on this site, St. John the Baptist Parish, LA ranks 2,759 most-constrained nationally, and 61 of 61 within Louisiana.

Further reading

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