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Orange County, California

USDA's soil survey flags shrink-swell clay on 14% of Orange County's mapped land and a shallow water table under basements on 3%, both below the national shares of 15% and 29%. None of the county is in drought on the September 22, 2026 Drought Monitor map.

FEMA's flood data list 227 flood losses here since 2016, 5% of them in buildings with basements. 57% of homes were built before 1980, against 50% nationally; the median home dates from 1977.

Data as of September 22, 2026 · sources

14%

expansive clay: shrink-swell limits slab homes

3%

high water table: limits basements

0%

in drought, September 22, 2026

57%

of homes built before 1980

Soil under Orange County

Expansive clay (limits slab homes)13.5%
High water table (limits basements)2.6%
Septic fields very limited76.5%
Clay swell (LEP, by area)3.8%
High-swell land (LEP 6%+)18.3%
Mapped soil501,104 acres
Soil seriesShare hereSeries nationally: expansive clay
Cieneba9%n/a
Myford8%n/a
Calleguas6%n/a
Metz5%n/a
Friant5%n/a
Alo5%n/a
Los Angeles County: 4%San Diego County: 17%Ventura County: 12%Riverside County: 3%San Bernardino County: 1%Kern County: 6%Santa Barbara County: 12%Imperial County: no dataOrange County Los AngelesSan DiegoVenturaRiversideSan BernardinoKernSanta BarbaraImperialOrange
Orange County (heavy outline) and nearby counties, shaded by expansive clay share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas CA678 (2025-09-08)

What the numbers mean here

Rain over the 12 months to August 2026: 14.44 in, 1.48 in above the 1991-2020 average year of 12.96 in.

USDA rates 77% of the land very limited for septic absorption fields.

With shrink-swell clay on 14% and a shallow water table on 3% of the land, the soil survey points to neither problem across most of Orange County; conditions still vary lot by lot.

Drought

0% of the county is in drought (D1 or worse) on the September 22, 2026 map. Part of the county was in drought in 8 of the last 52 weeks; the most was 100% of its area, in 7 weeks, most recently on the November 11, 2025 map.

September 30, 2025Share of area in drought, weeklySeptember 22, 2026
Category, September 22, 2026Share of county
D0 abnormally dry or worse0%
D1 moderate drought or worse0%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

227 flood losses since 2016, $3.0 million paid. The worst year was 2017, with 70. Foundations of the buildings, where recorded: 5% basements, 73% slabs, 8% crawl spaces, 13% elevated. Median water depth outside the building: 4 in.

YearFlood losses
201627
201770
20187
201929
202014
202111
20222
202322
202420
202516
2026 to date9

Rain

Average year, 1991-202012.96 in
12 months to August 202614.44 in (+1.48)
202514.95 in (+1.99)
Wettest year since 18951941: 29.69 in
Driest year since 18952013: 4.21 in
Days with 1 inch or more, normal at SANTA ANA FIRE STN (7 mi away)3.2

Homes

Housing units1,146,169
Median year built1977
Built before 198057%
Built 2000 or later18%
Owner-occupied56%
Median value, owner-occupied$962,600
Single-family detached49%

What repairs cost

Published ranges from cost guides, not quotes. More sources, and where they disagree.

WorkRangeSource
Foundation repair, US $2,200 to $8,200 Fixr, January 27, 2026
Pier-and-beam repair, US $2,000 to $15,000 Fixr, January 27, 2026
Foundation inspection, US $300 to $600 Fixr, January 31, 2025

Nearby counties

PlaceDistanceExpansive clayHigh water table
Los Angeles County, CA 45 mi 4% under 1%
San Diego County, CA 74 mi 17% 1%
Ventura County, CA 91 mi 12% 4%
Riverside County, CA 105 mi 3% 5%
San Bernardino County, CA 122 mi 1% under 1%
Kern County, CA 128 mi 6% 1%
Santa Barbara County, CA 142 mi 12% 4%
Imperial County, CA 146 mi n/a n/a

Sources: USDA SSURGO (September 8, 2025) · US Drought Monitor (September 22, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status