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Plymouth County, Massachusetts
A shallow water table limits basements on 51% of Plymouth County's mapped land, a higher share than 67% of US counties and the 2nd highest of 14 Massachusetts counties. Shrink-swell clay limits houses without basements on 0%.
14.7% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 875 flood losses here since 2016, 44% of them in buildings with basements. 62% of homes were built before 1980, against 50% nationally; the median home dates from 1971.
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 Plymouth County
| Expansive clay (limits slab homes) | 0.0% |
| High water table (limits basements) | 51.2% |
| Septic fields very limited | 85.8% |
| Clay swell (LEP, by area) | 0.8% |
| High-swell land (LEP 6%+) | 0.0% |
| Urban land, not rated | 2.9% |
| Mapped soil | 457,791 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Carver | 10% | n/a |
| Freetown | 6% | n/a |
| Hinckley | 5% | n/a |
| Plymouth | 4% | n/a |
| Merrimac | 4% | n/a |
| Deerfield | 4% | n/a |
How we count · survey areas MA023 (2025-09-05)
What the numbers mean here
On 51% of Plymouth 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: 43.68 in, 6.95 in below the 1991-2020 average year of 50.63 in.
USDA rates 86% of the land very limited for septic absorption fields.
Drought
14.7% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 40 of the last 52 weeks; the most was 100% of its area, in 12 weeks, most recently on the July 28, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 27.1% |
| D1 moderate drought or worse | 14.7% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
875 flood losses since 2016, $23.6 million paid. The worst year was 2018, with 731. Foundations of the buildings, where recorded: 44% basements, 15% slabs, 12% crawl spaces, 29% elevated. Median water depth outside the building: 23 in.
| Year | Flood losses |
|---|---|
| 2016 | 17 |
| 2017 | 14 |
| 2018 | 731 |
| 2019 | 7 |
| 2020 | 4 |
| 2021 | 39 |
| 2022 | 14 |
| 2023 | 8 |
| 2024 | 31 |
| 2025 | 7 |
| 2026 to date | 3 |
Rain
| Average year, 1991-2020 | 50.63 in |
| 12 months to August 2026 | 43.68 in (-6.95) |
| 2025 | 44.70 in (-5.93) |
| Wettest year since 1895 | 1972: 65.22 in |
| Driest year since 1895 | 1965: 26.28 in |
| Days with 1 inch or more, normal at PLYMOUTH-KINGSTON (2 mi away) | 14.9 |
Homes
| Housing units | 218,096 |
| Median year built | 1971 |
| Built before 1980 | 62% |
| Built 2000 or later | 18% |
| Owner-occupied | 78% |
| Median value, owner-occupied | $556,000 |
| 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 |
|---|---|---|---|
| Bristol County, MA | 24 mi | 0% | 63% |
| Norfolk County, MA | 26 mi | 0% | 34% |
| Suffolk County, MA | 28 mi | 0% | 11% |
| Bristol County, RI | 34 mi | 0% | 38% |
| Barnstable County, MA | 35 mi | 0% | 19% |
| Dukes County, MA | 42 mi | 0% | 17% |
| Newport County, RI | 44 mi | 0% | 66% |
| Providence County, RI | 44 mi | 0% | 42% |
Sources: USDA SSURGO (September 5, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status