I was looking at a house and noticed they had a condensation pump for a hot water heater going directly into one of the houses sewage pipes, which empties into the property's septic tank. See images below.

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Ignoring any possible local municipal code violations (if any), is this functionally sound? Could any obvious issue crop up? It's supposedly been like this for 5 years without a problem, but doesn't mean it won't ever be one 😆

I don't know off hand what utility in the house above is draining into that pipe.

  • that would be your sewage pipe (from the toilets
    – Traveler
    Commented Jul 8, 2022 at 22:15
  • Thank you, the set up is fine, but I would have preferred a P-trap stile connection, that would have prevented sewage fumes coming up
    – Traveler
    Commented Jul 8, 2022 at 22:20
  • Gotcha, maybe it can be modified easily enough to use a P-trap. Commented Jul 8, 2022 at 22:22
  • How much of the hose slack do you have
    – Traveler
    Commented Jul 8, 2022 at 22:25
  • I gave you points for posting pictures
    – Traveler
    Commented Jul 8, 2022 at 22:27

2 Answers 2


Dumping into the sewer is common and allowed by code the only problem is I do not see a P trap or U bend that prevents sewer gasses from backing up into the home there could be one closer to the drain pan and it would be fine.

Some don’t like condensate drains into waste drains as the condensate can etch metal but you have plastic and this will not cause a problem there.

Their just needs to be a trap to prevent sewer gas back flow called a P trap or U bend.


Take the drain pipe and run it so that the B point is slightly lover than A point.

That would prevent any sewage smells coming up due to always some water present in the low point of the U shape.


  • Please correct the spelling in your diagram: It's spelled sewage. Commented Jul 9, 2022 at 1:25

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