Montgomery County, Maryland
The most common soil here is Glenelg, on about 20% of the land: a loam, a balanced mix that crumbles in your hand. Gaila and Blocktown come next.
About 81% of the land drains well, and 9% stays wet for long stretches; groundwater comes within two feet of the surface under 12% of it.
USDA rates 82% of the land very limited for a standard septic drain field, and 45% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 7% of the land floods occasionally or more, and bedrock lies within 40 inches under 32% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in Montgomery County, Maryland, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
The biggest mapped areas
The dominant drainage class is Well drained and the dominant hydrologic group is B (moderate infiltration). The most common soil order is Ultisols — strongly weathered soils with clay-enriched subsoils, common in warm humid climates. 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 Montgomery County, Maryland. Search your address to find the exact soil composition, drainage, and series details at your specific location.
| Soil Map Unit | Acres | Drainage | Hydro Group | Dwellings | Septic |
|---|---|---|---|---|---|
| Glenelg silt loam, 3 to 8 percent slopes | 52K | Well drained | B | Not limited | Very limited |
| Gaila silt loam, 8 to 15 percent slopes | 17K | Well drained | B | Somewhat limited | Very limited |
| Brinklow-Blocktown channery silt loams, 15 to 25 percent slopes | 17K | Well drained | C | Very limited | Very limited |
| Brinklow-Blocktown channery silt loams, 8 to 15 percent slopes | 17K | Well drained | C | Very limited | Very limited |
| Glenelg silt loam, 8 to 15 percent slopes | 13K | Well drained | B | Somewhat limited | Very limited |
| Brinklow-Blocktown channery silt loams, 3 to 8 percent slopes | 12K | Well drained | C | Very limited | Very limited |
| Penn silt loam, 3 to 8 percent slopes | 12K | Well drained | B | Very limited | Very limited |
| Occoquan loam, 3 to 8 percent slopes | 12K | Well drained | B | Not limited | Very limited |
| Hatboro silt loam, 0 to 3 percent slopes, frequently flooded | 11K | Poorly drained | B/D | Very limited | Very limited |
| Glenelg-Urban land complex, 0 to 8 percent slopes | 10K | Well drained | B | Not limited | Somewhat limited |
| Blocktown channery silt loam, 15 to 25 percent slopes, very rocky | 9K | Well drained | D | Very limited | Very limited |
| Gaila silt loam, 3 to 8 percent slopes | 9K | Well drained | B | Not limited | Very limited |
| Baile silt loam, 0 to 3 percent slopes | 9K | Poorly drained | C/D | Very limited | Very limited |
| Wheaton-Urban land complex, 0 to 8 percent slopes | 8K | Well drained | B | Not limited | Somewhat limited |
| Glenelg-Urban land complex, 8 to 15 percent slopes | 7K | Well drained | B | Somewhat limited | Somewhat limited |
| Census water | 7K | Not rated | Not rated | ||
| Blocktown channery silt loam, 25 to 45 percent slopes, very rocky | 7K | Well drained | D | Very limited | Very limited |
| Occoquan loam, 8 to 15 percent slopes | 6K | Well drained | B | Somewhat limited | Very limited |
| Urban land | 5K | D | Not rated | Not rated | |
| Penn silt loam, 8 to 15 percent slopes | 5K | Well drained | B | Very limited | Very limited |
Soil Orders in This Area
The USDA classifies every soil into one of 12 soil orders. Here are the dominant orders found in this survey area.
What This Means
Building & Foundations
About 45% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 82% 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.