Symptoms
- Puddle or drips found under or behind the dryer
- Water inside the vent duct near the connection
- Musty smell along with the moisture
- Problem worse in cold weather for vented dryers
Likely causes
- CommonCondensation forming inside a vent duct that runs through cold spaceWarm, moist exhaust air condenses when it hits a cold duct section, like one running through an unheated attic or exterior wall.
- CommonVent duct sloped incorrectly, letting condensation run back toward the dryerVent runs should generally slope slightly downward toward the exterior to let any moisture drain outside, not back inside.
- PossibleLoose or disconnected vent connection dripping condensateA poor connection at the dryer or wall can leak accumulated moisture.
- PossibleCondenser/ventless dryer tank overflow or hose leakOn ventless models, a full tank, improperly seated tank, or leaking drain hose (if equipped) causes visible water.
- Less commonNearby plumbing or unrelated leak mistaken for dryer condensationSometimes the water source is actually a nearby washer, water heater, or pipe rather than the dryer.
What to do
- Confirm whether you have a standard vented dryer or a ventless condenser/heat pump model, since the cause differs.
- For vented dryers, check the vent duct route for sections passing through cold, unconditioned spaces.
- Ensure the vent duct slopes slightly downward toward the exterior exit point rather than back toward the dryer.
- Insulate exposed vent duct sections if condensation is occurring in a cold space like an attic.
- For ventless dryers, empty and reseat the water tank, and check any drain hose for leaks or disconnection.
- Rule out a nearby plumbing leak by checking the area when the dryer isn't running.
- Have a technician or HVAC professional address a persistent condensation issue in a long or poorly routed vent run.
Tools and parts
- Flashlight
Dryer vent duct insulationSearch: “dryer vent duct insulation wrap”
When to call a pro
If condensation in the vent persists after checking slope and insulation, have a technician reroute or insulate the duct properly.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.