This is normal
Probably normal: condensation
Water that beads all over the outside of the tank, dries up and comes back with humidity is condensation, not a leak. Drier air in the bathroom is the first fix.
Why this happens
This Old House says condensation forms when warm, humid air meets the cold surface of the tank, and that humidity, cold supply water and poor ventilation all play a part. Bob Vila says baths and showers make bathrooms the moistest room in the house, and This Old House says hot showers and baths add to the moisture in the air. If your dye test showed no leak and the tank is not running, the water on the outside most likely came from the air.
What to do
- Run the bathroom exhaust fan during showers. This Old House says to keep it running for at least 30 minutes afterward.
- Keep the bathroom door open when you can, or open a window, as This Old House suggests, so damp air does not sit in the room. This Old House also says that in warm months, air conditioning is a better way to cool the house than open windows.
- Squeegee the shower walls after use, another tip from This Old House.
- Wipe the tank and dry the floor under it. Bob Vila warns that ongoing drips can damage flooring or drywall and lead to mold, and This Old House notes a wet floor is a slip hazard.
- Check again in a few days. If it keeps happening in spite of better ventilation, Bob Vila says an anti-sweat valve is best left to a professional plumber, and a whole-house dehumidifier is a question for an HVAC professional.
When to stop. If the water does not dry up, comes from one spot, or the floor stays wet, treat it as a leak and call a licensed plumber. If water reaches an outlet, plug, cord, switch or light, including a light in the ceiling below, do not touch it and call an electrician. Ready.gov says not to touch electrical equipment if it is wet or if you are standing in water.
If it still worries you, tell the plumber
- The tank sweats only in humid weather or after showers, and the dye test showed no leak.
- Whether the bathroom has an exhaust fan and whether you run it.
- Whether the wall, floor or ceiling below has stains or soft spots.
- If it changes: when the water appears and whether it dries up.
Build the full list: what to tell the plumber.
Start this troubleshooter over
FourHome is our sister brand. Browse all FourHome replacement faucet and shower parts on the FourHome Amazon store. We earn from purchases made through this link.