Water Coming Up Through the Floor
Water rising through a floor is unsettling, and it always means something underneath needs attention. Here's how to figure out the source and what to do.
First: shut off the main water valve. If the water stops spreading, it's likely a plumbing leak. If it keeps coming, especially after rain, it's more likely groundwater or drainage.
The most common causes
| Cause | Clues | Home type |
|---|---|---|
| Slab leak (pipe under the concrete) | Warm spots on the floor, sound of running water, high water bill, meter moving with everything off | Slab homes |
| Burst or leaking pipe in the crawl space | Wet, soft or cupping floors, musty smell, water pressure drop | Crawl space homes |
| Groundwater / hydrostatic pressure | Appears after heavy rain, seeps along floor edges or cracks | Basements and slabs |
| Sewer or drain backup | Water near floor drains, bad smell, gurgling toilets | Any, especially basements |
| Appliance or water heater leak | Water spreading from a utility area under flooring | Any |
What to do right now
- Shut off the waterThis also tells you whether it's plumbing (stops) or groundwater (doesn't).
- Stay safeKeep away from outlets and cords on the floor. Sewage water needs professional cleanup.
- DocumentPhotos and video of where water is coming up and how far it has spread.
- Pull up rugs and move belongingsGet furniture off wet flooring.
- Call for helpA restoration company to extract and dry; they can also help pinpoint the source with moisture meters and thermal imaging.
Why you shouldn't wait
Water under flooring doesn't dry on its own. Laminate and engineered floors swell, hardwood cups, and the subfloor or pad underneath can stay wet for weeks and grow mold. Under a slab, a leak can also wash out soil and affect the foundation over time.
See also: burst pipe in the crawl space · flooded basements and crawl spaces · signs of hidden water damage
Frequently asked questions
How do I know if I have a slab leak?
Common signs include warm or damp spots on the floor, the sound of running water when everything is off, a water meter that keeps moving and a sudden jump in your water bill. A plumber can confirm it with leak detection equipment.
Does insurance cover water coming up through the floor?
It depends on the cause. Sudden plumbing leaks are often covered (though the pipe repair itself may not be). Groundwater and outside flooding usually aren't covered without flood insurance.
Water in your home? Get a local pro on the way.
Call and we'll connect you with an independent local water damage restoration company that serves your area. The referral is free, and many local companies answer around the clock.