Septic soil map by county
USDA rates the soil of almost every county in the country for a septic drainfield. This map draws the reason USDA gives for each one.
Find your county
Each state takes the reason that leads the most counties in it. A ZIP code opens that state.
What the colors mean
One row per reason, over every county on the map. The four rarest reasons lead 25 counties, so they share one row.
| Color | The reason USDA gives | Counties | Share of counties |
|---|---|---|---|
| Slow water movement | 1,814 | 56.2% | |
| Slope | 575 | 17.8% | |
| Depth to saturated zone | 459 | 14.2% | |
| Seepage, bottom layer | 159 | 4.9% | |
| Depth to bedrock | 157 | 4.9% | |
| Other reason | 25 | 0.8% | |
| No rating published | 40 | 1.2% |
USDA publishes no rating for a striped county. The map still draws it.
The leading reason in each state
A state is one color on the map and its counties are not. This table gives the share of each state that agrees with it.
| State | The reason that leads it | Counties | Share that agree |
|---|---|---|---|
| Alabama | Slow water movement | 52 of 67 | 77.6% |
| Alaska | Slope | 15 of 27 | 55.6% |
| Arizona | Slope | 6 of 14 | 42.9% |
| Arkansas | Slow water movement | 49 of 75 | 65.3% |
| California | Slope | 35 of 58 | 60.3% |
| Colorado | Slope | 31 of 63 | 49.2% |
| Connecticut | Slope | 5 of 8 | 62.5% |
| Delaware | Depth to saturated zone | 2 of 3 | 66.7% |
| Florida | Depth to saturated zone | 49 of 67 | 73.1% |
| Georgia | Slow water movement | 121 of 159 | 76.1% |
| Hawaii | Slope | 4 of 5 | 80% |
| Idaho | Slow water movement | 18 of 44 | 40.9% |
| Illinois | Slow water movement | 84 of 102 | 82.4% |
| Indiana | Slow water movement | 73 of 92 | 79.3% |
| Iowa | Slow water movement | 95 of 99 | 96% |
| Kansas | Slow water movement | 104 of 105 | 99% |
| Kentucky | Slow water movement | 60 of 120 | 50% |
| Louisiana | Slow water movement | 34 of 64 | 53.1% |
| Maine | Depth to saturated zone | 12 of 16 | 75% |
| Maryland | Slow water movement | 14 of 24 | 58.3% |
| Massachusetts | Seepage, bottom layer | 5 of 14 | 35.7% |
| Michigan | Seepage, bottom layer | 40 of 83 | 48.2% |
| Minnesota | Slow water movement | 43 of 87 | 49.4% |
| Mississippi | Slow water movement | 71 of 82 | 86.6% |
| Missouri | Slow water movement | 104 of 114 | 91.2% |
| Montana | Slow water movement | 27 of 56 | 48.2% |
| Nebraska | Slow water movement | 67 of 93 | 72% |
| Nevada | Slope | 15 of 17 | 88.2% |
| New Hampshire | Slope | 8 of 10 | 80% |
| New Jersey | Seepage, bottom layer | 10 of 21 | 47.6% |
| New Mexico | Slow water movement | 25 of 33 | 75.8% |
| New York | Depth to saturated zone | 28 of 62 | 45.2% |
| North Carolina | Slow water movement | 46 of 100 | 46% |
| North Dakota | Slow water movement | 32 of 53 | 60.4% |
| Ohio | Slow water movement | 47 of 88 | 53.4% |
| Oklahoma | Slow water movement | 67 of 77 | 87% |
| Oregon | Slope | 15 of 36 | 41.7% |
| Pennsylvania | Slope | 20 of 67 | 29.9% |
| Rhode Island | Depth to saturated zone | 3 of 5 | 60% |
| South Carolina | Slow water movement | 30 of 46 | 65.2% |
| South Dakota | Slow water movement | 53 of 66 | 80.3% |
| Tennessee | Slope | 55 of 95 | 57.9% |
| Texas | Slow water movement | 197 of 254 | 77.6% |
| Utah | Slow water movement | 12 of 29 | 41.4% |
| Vermont | Slope | 9 of 14 | 64.3% |
| Virginia | Slow water movement | 54 of 127 | 42.5% |
| Washington | Slope | 17 of 39 | 43.6% |
| West Virginia | Slope | 37 of 55 | 67.3% |
| Wisconsin | Slow water movement | 29 of 72 | 40.3% |
| Wyoming | Slope | 9 of 23 | 39.1% |
Sources
Every county here comes from one dataset. We read it on the date below.