Last reviewed and updated: 2026-09-24
Carpet or flooring that is damp with no visible source is usually being wet from underneath, a slab leak, a drain line failure under the floor, or groundwater, or from water traveling along framing from a leak elsewhere. Moisture mapping establishes the extent and direction of travel, and the water meter establishes whether it is your pressurized plumbing.
Damp flooring with no source above is usually being wet from underneath, which points to a slab leak or a drain line failure, or else to a concealed leak traveling along framing.
Where it is coming from
| Source | Clue | Confirms it |
|---|---|---|
| Slab leak | Constant, sometimes warm, meter turning | Pressure test and acoustic location |
| Drain line under the floor | Only wet after a shower, bath or washing machine cycle | Camera inspection or hydrostatic test |
| Water traveling from another room | Moisture trail leads away toward a bathroom or kitchen wall | Moisture mapping |
| HVAC condensate line blocked | Near the air handler; worse in humid weather with AC running | Inspect and clear the condensate line |
| Water heater or pan | Near the heater; check the pan and relief line | Visual inspection |
| Groundwater | Correlates with rain; at exterior walls; always cold | No meter movement |
| Window or door flashing failure | Appears after wind-driven rain, near an opening | Water testing the opening |
What to do
- Run the meter test. Movement with everything off means pressurized plumbing.
- Note the timing. Constant dampness means a supply leak. Dampness only after a shower or laundry means a drain.
- Check whether it correlates with rain. If it does, it is probably groundwater or an envelope failure, not plumbing.
- Photograph and document before you lift anything or start drying.
- Lift a corner of the carpet if you can do so without damage, and check whether the pad and the slab beneath are wet.
- Start drying while you investigate. Mold can begin establishing within roughly 24 to 48 hours in Georgia humidity.
Do not just dry it and move on. Drying the carpet without finding the source means it comes back, and the second time it comes back the damage is worse and an insurer is more likely to call it gradual rather than sudden.
Frequently asked questions
Why is my carpet wet with no visible leak?
The water is most likely arriving from underneath, a slab leak, a drain line failure below the floor, or groundwater, or traveling along framing from a leak elsewhere in the house and surfacing where gravity lets it.
How do I tell a supply leak from a drain leak under the floor?
Timing. A supply line is pressurized constantly, so it produces constant dampness. A drain leak only appears while water is flowing through that drain: after a shower, a bath or a washing machine cycle.
Could it be the air conditioning?
Yes, quite often. A blocked HVAC condensate line overflows and wets the floor near the air handler, typically in humid weather with the system running hard. It is worth checking before assuming a plumbing leak.
How quickly should I dry it?
Immediately. In Georgia humidity mold can begin establishing within roughly 24 to 48 hours. Document everything with photographs first, then extract and dry while you investigate the source.
Can I just dry the carpet and see if it comes back?
It will come back if the source is still there, and the second occurrence is usually worse. It also weakens an insurance claim, because a recurring problem is easier for an insurer to characterize as gradual deterioration rather than a sudden failure.