Fairfax County, Virginia
The most common soil here is Glenelg, on about 16% of the land: a loam, a balanced mix that crumbles in your hand. Wheaton and Codorus come next.
About 62% of the land drains well, and 12% stays wet for long stretches; groundwater comes within two feet of the surface under 22% of it.
USDA rates 72% of the land very limited for a standard septic drain field, and 35% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 8% of the land floods occasionally or more, and bedrock lies within 40 inches under 5% 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 Fairfax County, Virginia, 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 C (slow infiltration, moderate runoff). The most common soil order is Entisols — young soils with little profile development, often on floodplains or steep slopes. 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 Fairfax County, Virginia. 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 |
|---|---|---|---|---|---|
| Urban land | 27K | Not rated | Not rated | ||
| Wheaton-Glenelg complex, 2 to 7 percent slopes | 19K | Well drained | C | Not limited | Very limited |
| Wheaton-Glenelg complex, 7 to 15 percent slopes | 18K | Well drained | C | Somewhat limited | Very limited |
| Codorus and Hatboro soils, 0 to 2 percent slopes, occasionally flooded | 12K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Glenelg silt loam, 7 to 15 percent slopes | 12K | Well drained | B | Somewhat limited | Somewhat limited |
| Water | 8K | Not rated | Not rated | ||
| Glenelg silt loam, 15 to 25 percent slopes | 8K | Well drained | B | Very limited | Very limited |
| Urban land-Wheaton complex | 6K | Not rated | Not rated | ||
| Kingstowne-Sassafras-Neabsco complex, 2 to 7 percent slopes | 6K | Well drained | C | Somewhat limited | Very limited |
| Glenelg silt loam, 2 to 7 percent slopes | 6K | Well drained | B | Not limited | Somewhat limited |
| Wheaton-Glenelg complex, 15 to 25 percent slopes | 5K | Well drained | C | Very limited | Very limited |
| Glenelg silt loam, 25 to 45 percent slopes | 4K | Well drained | B | Very limited | Very limited |
| Urban land-Chantilly complex | 4K | Not rated | Not rated | ||
| Wheaton-Meadowville complex, 2 to 7 percent slopes | 4K | Well drained | C | Not limited | Very limited |
| Nathalie gravelly loam, 7 to 15 percent slopes | 3K | Well drained | B | Somewhat limited | Very limited |
| Codorus silt loam, 0 to 2 percent slopes, occasionally flooded | 3K | Somewhat poorly drained | B/D | Very limited | Very limited |
| Sassafras-Marumsco complex, 7 to 15 percent slopes | 3K | Well drained | B | Somewhat limited | Very limited |
| Urban land-Kingstowne complex | 3K | Not rated | Not rated | ||
| Grist Mill-Mattapex complex, 2 to 7 percent slopes | 3K | Well drained | C | Somewhat limited | Very limited |
| Sassafras-Marumsco complex, 25 to 45 percent slopes | 3K | 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 35% of soils have significant building limitations, while the rest are generally suitable. Check specific sites carefully — conditions vary across the area.
Septic Systems
About 72% 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.