Leaks
Water Coming Up Through the Basement Floor: Causes and Fixes
Updated · Holdfast editorial · 2 min read
Why does it happen?
Slow-draining soils and high spring groundwater push water up under the slab when drain tile fails.
Where does it show up?
Common places:
- Cracks in the floor
- The joint where floor meets wall
- Around old floor drains or pipes
How is it fixed?
Interior perimeter drainage and a sump relieve the pressure. Sealing cracks alone usually moves the water elsewhere.
When should you call?
Call if water appears after rains or thaws, or if the floor stays damp.
Is it groundwater, sewer or plumbing?
Clear water that seeps up through floor cracks or the floor-wall joint, especially after rain, is groundwater under pressure. Dirty or smelly water from the floor drain is a sewer backup and a plumbing problem. Water that appears with no rain may be a leaking supply line under the slab.
What fixes groundwater under the floor?
Sealing floor cracks alone rarely works, because the water finds another path. The lasting fix relieves the pressure: an interior drain around the perimeter, below the slab, leading to a sump pump. In older homes, original clay drain tile has often clogged or collapsed, which is why water that used to drain away now comes up.
Call a professional if
- Water at the floor-wall seam
- Water rising through floor cracks
- Seepage along several walls
- Old clay drain tile that has failed
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About interior drainage systemsWhat else do people ask about this?
Can I seal floor cracks myself?
Sealing may help small cracks but doesn't stop groundwater pressure.
Why does it only happen in spring?
Snowmelt and spring rains raise groundwater levels.
Where can I verify this information about your home?
- 1USDA Natural Resources Conservation Service: Web Soil SurveyLook up soil drainage class and shrink-swell potential for any lot in your home.
- 2FEMA: Flood Map Service CenterCheck whether a property in your home is in a mapped flood zone before finishing a basement.
- 3U.S. Environmental Protection Agency: RadonWhy basements in your home should be tested for radon, and how sealed sumps fit with mitigation.
- 4NOAA National Centers for Environmental Information: U.S. Climate NormalsAverage precipitation, snowfall and temperatures for weather stations near your home.
- 5Federal Trade Commission: Hiring a ContractorWhat to check before hiring: licensing, insurance, written estimates and payment terms.
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