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Pierce County, Washington
A shallow water table limits basements on 34% of Pierce County's mapped land, a higher share than 52% of US counties. Shrink-swell clay limits houses without basements on 2%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 152 flood losses here since 2016, 20% of them in buildings with basements. 42% of homes were built before 1980, against 50% nationally; the median home dates from 1986.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Pierce County
| Expansive clay (limits slab homes) | 2.4% |
| High water table (limits basements) | 33.6% |
| Septic fields very limited | 91.6% |
| Clay swell (LEP, by area) | 1.4% |
| High-swell land (LEP 6%+) | 2.7% |
| Urban land, not rated | 2.6% |
| Mapped soil | 1,115,458 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Kapowsin | 6% | n/a |
| Spanaway | 6% | n/a |
| Alderwood | 5% | n/a |
| Nimue | 4% | n/a |
| Harstine | 4% | n/a |
| Barneston | 3% | n/a |
How we count · survey areas WA634 (2025-08-28), WA653 (2025-08-28), WA754 (2025-08-28), WA776 (2025-08-28), WA777 (2025-08-28)
What the numbers mean here
On 34% of Pierce County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 66.29 in, 0.86 in above the 1991-2020 average year of 65.43 in.
USDA rates 92% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 20 of the last 52 weeks; the most was 100% of its area, in 8 weeks, most recently on the December 9, 2025 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
152 flood losses since 2016, $4.9 million paid. The worst year was 2022, with 64. Foundations of the buildings, where recorded: 20% basements, 24% slabs, 33% crawl spaces, 23% elevated. Median water depth outside the building: 12 in.
| Year | Flood losses |
|---|---|
| 2016 | 9 |
| 2017 | 5 |
| 2018 | 3 |
| 2019 | 8 |
| 2020 | 14 |
| 2021 | 9 |
| 2022 | 64 |
| 2023 | 2 |
| 2024 | 4 |
| 2025 | 29 |
| 2026 to date | 5 |
Rain
| Average year, 1991-2020 | 65.43 in |
| 12 months to August 2026 | 66.29 in (+0.86) |
| 2025 | 61.06 in (-4.37) |
| Wettest year since 1895 | 1933: 87.77 in |
| Driest year since 1895 | 1952: 36.70 in |
| Days with 1 inch or more, normal at TACOMA #1 (18 mi away) | 6.1 |
Homes
| Housing units | 369,709 |
| Median year built | 1986 |
| Built before 1980 | 42% |
| Built 2000 or later | 29% |
| Owner-occupied | 65% |
| Median value, owner-occupied | $526,600 |
| Single-family detached | 65% |
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 |
|---|---|---|---|
| Thurston County, WA | 33 mi | 3% | 34% |
| King County, WA | 33 mi | under 1% | 38% |
| Lewis County, WA | 34 mi | 7% | 20% |
| Kitsap County, WA | 47 mi | under 1% | 65% |
| Mason County, WA | 52 mi | under 1% | 45% |
| Cowlitz County, WA | 64 mi | 4% | 10% |
| Kittitas County, WA | 70 mi | 5% | 14% |
| Skamania County, WA | 72 mi | 4% | 5% |
Sources: USDA SSURGO (August 28, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status