Suffolk County, New York
The dominant drainage class is Well drained and the dominant hydrologic group is A (high infiltration, low runoff). This report summarizes the major soil map units across the survey area to help you understand what to expect when buying, building, or gardening in Suffolk County, New York.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Water | 161K | Not rated | Not rated | ||
| Riverhead sandy loam, 0 to 3 percent slopes | 69K | Well drained | A | Not limited | Very limited |
| Haven loam, 0 to 2 percent slopes | 60K | Well drained | B | Not limited | Very limited |
| Riverhead and Haven soils, graded, 0 to 8 percent slopes | 58K | Well drained | A | Not limited | Very limited |
| Carver and Plymouth soils, 3 to 15 percent slopes | 43K | Excessively drained | A | Somewhat limited | Very limited |
| Plymouth loamy coarse sand, 0 to 3 percent slopes | 39K | Excessively drained | A | Not limited | Very limited |
| Carver and Plymouth soils, 15 to 35 percent slopes | 34K | Excessively drained | A | Very limited | Very limited |
| Cut and fill land, gently sloping | 32K | Moderately well drained | Not rated | Not rated | |
| Riverhead sandy loam, 3 to 8 percent slopes | 32K | Well drained | A | Not limited | Very limited |
| Plymouth loamy coarse sand, 3 to 8 percent slopes | 27K | Excessively drained | A | Not limited | Very limited |
| Carver and Plymouth soils, 0 to 3 percent slopes | 25K | Excessively drained | A | Not limited | Very limited |
| Tidal marsh | 16K | Very poorly drained | Not rated | Not rated | |
| Haven loam, 2 to 6 percent slopes | 15K | Well drained | B | Not limited | Very limited |
| Plymouth loamy coarse sand, 8 to 15 percent slopes | 13K | Excessively drained | A | Somewhat limited | Very limited |
| Bridgehampton silt loam, 0 to 2 percent slopes | 10K | Well drained | B | Not limited | Very limited |
| Montauk loam, 3 to 8 percent slopes | 9K | Well drained | C | Somewhat limited | Very limited |
| Riverhead sandy loam, 8 to 15 percent slopes | 8K | Well drained | A | Somewhat limited | Very limited |
| Urban land | 6K | Not rated | Not rated | ||
| Beaches, sand | 6K | Very limited | Very limited | ||
| Fill land, dredged material | 6K | Not rated | Not rated |
What This Means
Building & Foundations
Most soils are generally favorable for residential construction. Standard foundations are usually viable, though site-specific evaluation is always recommended.
Septic Systems
About 67% of soils are rated "very limited" for septic absorption fields. Despite good drainage overall, limitations may stem from shallow bedrock, steep slopes, or seasonal conditions. Engineered or alternative systems are frequently required. Always get a professional perc test before purchasing land that needs septic.
Gardening & Agriculture
Well-drained soils on sloped terrain — good for most plants but watch for erosion. Terracing, contour planting, and mulching help retain moisture and topsoil. Drip irrigation is more effective than sprinklers on slopes.