Symptoms
- Moisture or beads of water on the outside of the tank
- More noticeable in humid weather or right after a hot shower nearby
- No steady drip or growing puddle underneath
- Tank was recently filled with cold water (like after installation)
Likely causes
- CommonAmbient humidity condensing on a cooler tank surfaceThis is especially common right after installation when the tank is still cool from the fresh cold water fill, or in humid basements and closets.
- CommonCondensation on cold water inlet pipe dripping down onto the tankThe cold pipe sweats and drips run down the tank's side, appearing as if the tank itself is wet.
- PossibleActual leak from a fitting or the tank being mistaken for condensationA genuine leak will typically continue and pool, unlike condensation which comes and goes with humidity.
What to do
- Wipe the tank completely dry and monitor over the next hour or two rather than assuming it's a leak immediately.
- Check nearby humidity sources, like a recently run shower, laundry, or a naturally damp basement.
- Trace any moisture back along the cold inlet pipe to see if it's dripping down from there rather than originating at the tank itself.
- Look at whether the moisture reappears evenly across the tank's surface (suggesting condensation) versus concentrated at one fitting or seam (suggesting a real leak).
- Improve ventilation in the space if condensation is a recurring issue, especially in an enclosed closet.
- If moisture keeps returning at a specific spot rather than generally across the surface, treat it as a possible leak and investigate that fitting directly.
Tools and parts
- Towel
- Flashlight
When to call a pro
If wiping it dry and monitoring shows the moisture keeps returning at one specific point, have a plumber check that spot for an actual leak.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.