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San Bernardino County, California
USDA's soil survey flags shrink-swell clay on 1% of San Bernardino County's mapped land and a shallow water table under basements on under 1%, both below the national shares of 15% and 29%. The soil survey maps 30% of the county's land area; these shares describe the mapped part.
53.3% of the county is in drought on the September 22, 2026 Drought Monitor map, up from 35.2% a week earlier. FEMA's flood data list 121 flood losses here since 2016, 2% of them in buildings with basements. 43% of homes were built before 1980, against 50% nationally; the median home dates from 1983.
Data as of September 22, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, September 22, 2026
of homes built before 1980
Soil under San Bernardino County
| Expansive clay (limits slab homes) | 0.6% |
| High water table (limits basements) | 0.4% |
| Septic fields very limited | 68.6% |
| Clay swell (LEP, by area) | 1.7% |
| High-swell land (LEP 6%+) | 1.4% |
| Mapped soil | 3,893,429 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Cajon | 10% | n/a |
| Arizo | 8% | n/a |
| Carrizo | 3% | n/a |
| Dalvord | 3% | n/a |
| Bryman | 2% | n/a |
| Tujunga | 2% | n/a |
How we count · survey areas AZ656 (2025-08-27), CA669 (2025-09-08), CA671 (2025-09-08), CA677 (2025-09-08), CA697 (2025-09-08), CA698 (2025-09-08), CA699 (2025-09-08), CA795 (2025-09-08), CA803 (2025-09-09), CA805 (2025-09-08)
What the numbers mean here
Rain over the 12 months to August 2026: 6.48 in, 0.11 in below the 1991-2020 average year of 6.59 in.
USDA rates 69% of the land very limited for septic absorption fields.
With shrink-swell clay on 1% and a shallow water table on under 1% of the land, the soil survey points to neither problem across most of San Bernardino County; conditions still vary lot by lot.
Drought
53.3% of the county is in drought (D1 or worse) on the September 22, 2026 map. Part of the county was in drought in 30 of the last 52 weeks; the most was 98.7% of its area, in 4 weeks, most recently on the November 11, 2025 map.
| Category, September 22, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 86% |
| D1 moderate drought or worse | 53.3% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
121 flood losses since 2016, $4.0 million paid. The worst year was 2025, with 38. Foundations of the buildings, where recorded: 2% basements, 73% slabs, 13% crawl spaces, 11% elevated. Median water depth outside the building: 6.5 in.
| Year | Flood losses |
|---|---|
| 2016 | 6 |
| 2017 | 16 |
| 2018 | 3 |
| 2019 | 10 |
| 2020 | 3 |
| 2021 | 8 |
| 2022 | 13 |
| 2023 | 16 |
| 2024 | 8 |
| 2025 | 38 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 6.59 in |
| 12 months to August 2026 | 6.48 in (-0.11) |
| 2025 | 7.83 in (+1.24) |
| Wettest year since 1895 | 1941: 13.82 in |
| Driest year since 1895 | 1953: 2.26 in |
| Days with 1 inch or more, normal at BAKER (30 mi away) | 0.6 |
Homes
| Housing units | 743,886 |
| Median year built | 1983 |
| Built before 1980 | 43% |
| Built 2000 or later | 22% |
| Owner-occupied | 62% |
| Median value, owner-occupied | $505,000 |
| Single-family detached | 70% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Riverside County, CA | 74 mi | 3% | 5% |
| Clark County, NV | 114 mi | under 1% | under 1% |
| Orange County, CA | 122 mi | 14% | 3% |
| Los Angeles County, CA | 127 mi | 4% | under 1% |
| San Diego County, CA | 131 mi | 17% | 1% |
| Imperial County, CA | 134 mi | n/a | n/a |
| Inyo County, CA | 137 mi | n/a | n/a |
| La Paz County, AZ | 145 mi | 2% | under 1% |
Sources: USDA SSURGO (September 9, 2025) · US Drought Monitor (September 22, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status