Here is another madness my heat pump & heat pump water heater installer did: The condensate drain (operated by a pump) runs directly on the concrete, next to the exterior wall (and hence foundation). This is especially frustrating because you can see there is a downspout drain on the left side which I believe it would have been possible to drain it.

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Initially I thought this is no big deal at all because it's not a lot of water, it's just a few times a day and it's definitely much less than rain would be anyway. But after a few months I see moss growing (see pictures).

Is this really a problem that I need to address?

  • Is your climate warm enough that outdoor freezing is never a concern?
    – Greg Hill
    Oct 2, 2023 at 21:05
  • Yes, California, Bay Area, never freezing.
    – divB
    Oct 2, 2023 at 21:06
  • Looks to me like the real problem is where the water collects in the expansion joints.
    – Huesmann
    Oct 3, 2023 at 12:27

2 Answers 2


Personally, I'd probably just shove a gutter deflector under it to push the water a bit farther from the house to where it will dry out more easily... In my installation the condensate drains are like yours, but are draining into dirt so the small amount of additional water is harmless.


If the concrete otherwise tends to stay clean of moss, so this becomes unsightly, you ought to fix it.

Using the nearby rainwater drain is a good idea.

An easy way to do this:

  • Cut out a section of downspout about 6 to 12 inches above ground and replace it with a downspout Y connector. This provides two entry points into the drain, without having to tinker with the PVC drain itself, which would be hard because it's buried in concrete and damaged.
  • Reconnect the downspout to one side of the Y.
  • Directly from the condensate pump, route a new condensate line through your crawl space to near the downspout, about 6 inches above the new Y connector. Then route it down and into the wye. Connect it loosely in a way that the water will fall into the drain.
  • You can make or buy an aluminum cover, cutting a hole in it for the condensate line but -- loosely -- so that if a clog, further down the drain line, causes water to be backed up to this point, the backed up water will flow over the Y and onto the ground, not back into the condensate pump.

This won't look beautiful but I think nicer options would involved digging up the damaged downspout adapter.

  • 1
    OP mentions that there's a condensate pump. The pump may (should?) be strong enough to lift the condensate over the door, so it might be possible to re-route the condensate drain line indoors to cross above the door and exit high or low on the left side.
    – Greg Hill
    Oct 2, 2023 at 21:37
  • Actually left and right of the door is crawlspace, so regardless I could re-route the condensate line in the crawlspace. But I am not sure I understand the answer. Is the suggestion to route it into the downspout drain or not?If yes, what is the best way to route it into the downspout drain? Yes, downspout comes from roof gutters.
    – divB
    Oct 2, 2023 at 21:42
  • I revised my answer so hopefully it's clearer, and also accounts now for the fact you have a pump, that I missed earlier.
    – jay613
    Oct 2, 2023 at 22:47

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