Maricopa County, Arizona
USDA's soil survey flags shrink-swell clay on 3% of Maricopa County's mapped land and a shallow water table under basements on 1%, both below the national shares of 15% and 29%. The soil survey maps 75% of the county's land area; these shares describe the mapped part.
93.8% of the county is in drought on the September 22, 2026 Drought Monitor map, down from 100% a week earlier. FEMA's flood data list 281 flood losses here since 2016, 6% of them in buildings with basements. 29% of homes were built before 1980, against 50% nationally; the median home dates from 1993.
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 Maricopa County
| Expansive clay (limits slab homes) | 3.1% |
| High water table (limits basements) | 0.6% |
| Septic fields very limited | 44.3% |
| Clay swell (LEP, by area) | 2.5% |
| High-swell land (LEP 6%+) | 2.5% |
| Mapped soil | 4,386,623 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Gilman | 6% | n/a |
| Gunsight | 5% | n/a |
| Mohall | 4% | n/a |
| Laveen | 4% | n/a |
| Rillito | 3% | n/a |
| Antho | 3% | n/a |
How we count · survey areas AZ645 (2025-08-28), AZ651 (2025-08-27), AZ653 (2025-08-27), AZ655 (2025-08-27), AZ658 (2025-08-27), AZ703 (2025-08-27)
What the numbers mean here
Rain over the 12 months to August 2026: 8.08 in, 0.49 in below the 1991-2020 average year of 8.57 in.
With shrink-swell clay on 3% and a shallow water table on 1% of the land, the soil survey points to neither problem across most of Maricopa County; conditions still vary lot by lot.
Drought
93.8% of the county is in drought (D1 or worse) on the September 22, 2026 map. Part of the county was in drought in 52 of the last 52 weeks; the most was 100% of its area, in 27 weeks, most recently on the September 15, 2026 map.
| Category, September 22, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 93.8% |
| D2 severe or worse | 75.8% |
| D3 extreme or worse | 20.9% |
| D4 exceptional | 0% |
Flood losses since 2016
281 flood losses since 2016, $5.9 million paid. The worst year was 2016, with 67. Foundations of the buildings, where recorded: 6% basements, 92% slabs, 1% crawl spaces, 1% elevated. Median water depth outside the building: 4 in.
| Year | Flood losses |
|---|---|
| 2016 | 67 |
| 2017 | 12 |
| 2018 | 53 |
| 2019 | 17 |
| 2020 | 4 |
| 2021 | 52 |
| 2022 | 38 |
| 2023 | 7 |
| 2024 | 4 |
| 2025 | 24 |
| 2026 to date | 3 |
Rain
| Average year, 1991-2020 | 8.57 in |
| 12 months to August 2026 | 8.08 in (-0.49) |
| 2025 | 8.17 in (-0.40) |
| Wettest year since 1895 | 1905: 19.05 in |
| Driest year since 1895 | 1956: 3.06 in |
| Days with 1 inch or more, normal at TOLLESON 1 E (16 mi away) | 0.8 |
Homes
| Housing units | 1,884,334 |
| Median year built | 1993 |
| Built before 1980 | 29% |
| Built 2000 or later | 37% |
| Owner-occupied | 65% |
| Median value, owner-occupied | $452,800 |
| Single-family detached | 64% |
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 |
|---|---|---|---|
| Pinal County, AZ | 72 mi | 15% | under 1% |
| Yavapai County, AZ | 91 mi | 29% | under 1% |
| Yuma County, AZ | 91 mi | 1% | under 1% |
| La Paz County, AZ | 93 mi | 2% | under 1% |
| Pima County, AZ | 94 mi | 9% | 0% |
| Gila County, AZ | 102 mi | 30% | under 1% |
| Graham County, AZ | 154 mi | 32% | under 1% |
| Santa Cruz County, AZ | 158 mi | 16% | 0% |
Sources: USDA SSURGO (August 28, 2025) · US Drought Monitor (September 22, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status