Water spitting out of pump vent pipe
Water spits directly out of the top of the white PVC vent pipe and secondary drain line every single time the pump runs. This continuous spilling or dripping is tied to the unit's operation, stopping immediately when the fan is turned off.
What the numbers show
Counted from the threads quoted below. How we count
- Most of it landed at once — the busiest month was September 2026, with 7 people.
- This comes up 11.2× more often in r/Plumbing than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Checking where the line ties into the main drainDid this help you?
- 2Inspecting for gunk or a stuck check valveDid this help you?
- 3Clearing the primary line with compressed air and a shop vacuumDid this help you?
- 4Applying epoxy, concrete, or sealant around the pipe exitDid this help you?
- 5Using foam or JB Weld products to patch gapsDid this help you?
- 6Moving nearby items out of the way of the waterDid this help you?
- 7Calling the plumbers backDid this help you?
- 8Inspecting or fixing the fittingDid this help you?
- 9Calling the installation company to fix the joint under warrantyDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“The two pvc pipes run out from the furnace, the other one is a drain from the tankless water heater. Does a tankless water heater purge or release water like this possibly?”source ↗
“Yeah the temperature and pressure relief valve is dumping. Something is wrong”source ↗
“That is a crazy amount of water. Broken relief valve?”source ↗
“Small bit of water comes through here during moderate to severe rainfall, the sump works.”source ↗
“if its already not got any gap like it looks like and its still leaking sounds more like maybe that elbow has got cracked or something”source ↗
“I guess I'll try that first before diving in further, I'll wait til it dries then hit it with fome jb weld stuff and see how it goes.”source ↗
“Everytime my pump runs water spits out of the white pvc from the top.”source ↗