Last reviewed and updated: 2026-09-24
Water appearing through a slab or at the base of a wall is either a plumbing leak under the foundation or groundwater getting in from outside. The quickest way to tell them apart is rain: groundwater intrusion correlates with rainfall and is usually worse near exterior walls, while a plumbing leak continues in dry weather and often appears in the middle of a room. The water meter settles it: if the meter turns with everything off, it is your plumbing.
If water is actively escaping, close the main shut-off first: that is an emergency. Otherwise it is either plumbing or groundwater, and the meter test settles which in twenty minutes. If it is plumbing, it is usually a slab leak or a failed drain line below the floor.
Telling them apart
| Indicator | Plumbing leak | Groundwater intrusion |
|---|---|---|
| Timing | Constant, unrelated to weather | Appears or worsens during and after rain |
| Location | Often mid-room, or tracking along a pipe route | Usually at exterior walls, corners or the slab edge |
| Water meter | Turns with everything off | No movement |
| Temperature | Can be warm if it is a hot line | Always cold |
| Water bill | Rising | Normal |
| Seasonality | Year round | Worse in wet seasons |
| Smell | Clean, or musty if long running | Often earthy or musty |
What to do now
- Run the meter test. Everything off, watch the low-flow indicator. Movement means plumbing.
- Photograph everything before you clean up. Where the water is, how much, and the meter reading. You cannot recreate this evidence later.
- Cut power to the area at the breaker if water is near outlets or appliances.
- Extract and dry. In Georgia humidity mold can begin establishing within a day or two.
- If it is plumbing, close the main shut-off to stop the loss while you arrange detection.
- If it is groundwater, look outside. Blocked gutters, downpipes discharging at the foundation, negative grading and failed french drains cause most of it.
Both matter for insurance, differently. A sudden plumbing failure is generally the stronger claim. Groundwater and surface water intrusion are excluded under most standard homeowners policies, which is why establishing the source early, and documenting it, is worth the effort.
Frequently asked questions
Why is water coming up through my concrete floor?
Either a plumbing line under the slab is leaking, or groundwater is being forced up through the concrete from outside. The water meter distinguishes them: if it turns with every fixture off, it is your plumbing.
How do I know if it is groundwater or a leak?
Groundwater correlates with rainfall, is usually worst at exterior walls and corners, is always cold, and does not affect your water bill. A plumbing leak continues in dry weather, often appears mid-room, can be warm if it is a hot line, and shows up on the meter and the bill.
Is water through the slab an emergency?
Treat it urgently. Cut power to the area if water is near electrics, document everything with photographs before cleaning, extract and dry quickly, and close the main shut-off if the meter shows it is plumbing.
Does insurance cover water coming through the foundation?
It depends on the source. A sudden plumbing failure is generally the stronger claim. Groundwater and surface water intrusion are excluded under most standard homeowners policies, which is why establishing and documenting the source early matters.
Can a slab leak damage my foundation?
Over time, yes. Water running continuously beneath a slab can wash out or soften the supporting soil, and in Georgia's expansive clay it can also cause the soil to swell. Either can move the foundation, which is far more expensive than the plumbing repair.