After the contractors installed the heat pump near my house, they pulled the drip line (that is connected to the condensate pump near the furnace) right next to the outdoor unit, which results in:

  1. Dripping water on the sidewalk all the time.
  2. Mossy growth near the outdoor unit.
  3. Water leaking towards the foundation.

Outdoor heat pump unit with water pooling next to it

Outdoor heat pump unit with water pooling next to it

Outdoor heat pump unit with water pooling next to it

I am not too concerned about (3) since rain probably causes more water to get that close to the foundation, but I feel like there likely is a better way to route the water from basically dripping under the unit slowly until it makes its way to the grass.

What would be the best approach here? Do I just get a PVC pipe and put it on a slope so that the water goes right into the grass, or is there a better recommended approach folks have seen/built?

  • 3
    Not really a "best" way to do it, but I've seen setups where people get a barbed fitting and additional hose and use this to keep a bird bath full. If you have a bird bath and are sick of filling it, do that!
    – Sidney
    Commented Jul 14, 2023 at 17:30
  • 1
    My window unit drips into a fish pond made of a large planter. I have minnows, lily pads and native plants. But OP's drain is too low for that, unless he can excavate a pond, and too low for a typical bird bath.
    – Wastrel
    Commented Jul 15, 2023 at 14:13

5 Answers 5


Two proposals

1- Extend the drip pipe to the grass using a pvc pipe of proper diameter

2- My preferred (I do it now), use a bucked to capture the very clean no minerals or calcium water (soft) to selectively water the plants.

Pending on the size of the heat exchanger coil and humidity factor, you can collect 1-3 gallons, or even more a day

  • These are really the best ideas. The problem with running the drip line onto the grass is you create a swamp.
    – Wastrel
    Commented Jul 15, 2023 at 14:18
  • Love the idea - thank you, that's precisely what I am doing now (collecting water in a bucket to water plants).
    – Den
    Commented Jul 18, 2023 at 17:19

Put a "gutter splash block" (standard item) under it to route the water away from the house to the grass while keeping the pipe short (less potential of clogging the pipe and backing up .vs. extending the pipe.)

  • Great idea, thank you for the suggestion! I haven't thought about the gutter splash block, but that is exactly what might be needed to do here without a pipe extension.
    – Den
    Commented Jul 18, 2023 at 17:21

One thing that is done in some areas is the condensate drain line is run to a location under a bathroom sink and is tied into the drain line before the P-trap. All condensate goes down the houses sewer system and is never seen. Since you tie in before the P-Trap, sewer gasses in the condensate line are not an issue.

This is the system I've always known, and I was quite surprised to learn that in other areas the drain dumps outside leaving a constant wet spot on the ground.

  • 3
    Some locations do not want additional water flow (and unmetered at that!) into the sewer system. Other locations don't mind or actively want it. It's local.
    – Ecnerwal
    Commented Jul 14, 2023 at 20:54
  • 2
    Ah, that would explain why none of these answers are, put it down the drain like a sane person +1. Probably don't have a gas fired furnace either, as that condensate is slightly caustic, it has to go somewhere else (into a drain pipe; not your plants or for birds), so that's where you put the AC line too, because the furnace already has a drain scheme, which is usually a condensate pump.... and that's probably what you're talking about, as it'd likely be too high to gravity feed into the above of a p-trap. And I'd assume the OP has neither a pump, nor a floor drain accessible.
    – Mazura
    Commented Jul 15, 2023 at 0:26
  • Thanks for the suggestion, folks - I think putting it into the sewer system would require quite a bit of re-work. @Mazura - so, behind the scenes there is actually a gas furnace, but there is also a condensate pump that I have that gets the condensate from inside the building to the outside. There is no floor drain near the furnace, so it has to be pumped outside. I've been using the water for plants and flowers so far.
    – Den
    Commented Jul 18, 2023 at 17:26

In my location 95% of homes have an AC unit. The codes for most counties say the condensate line must terminate at least 12" away from a building foundation and have a Trap. (Here they are called "lizard traps" and prevent the little lizards from crawling into the air handler.)

Just considering best practices and common sense, I would add a trap and extend the drain off the concrete at least the 12" away from the house.

  • Great suggestion, thank you! For my own reference, how would I go about connecting the existing drain line into a trap?
    – Den
    Commented Jul 18, 2023 at 17:27

Your fastest option would be to cut a small piece off the end of the condensate line, maybe an inch or so, then Take the piece to your local home store (Home Depot, Lowes, etc) and get a male-male hose adapter that fits in that hose piece, could be plastic or brass. In that same plumbing section grab a roll of silicone or plastic tubing of the same diameter that the adapter fits into that you can take home and connect them to the existing condensate line and extend the hose to go further away from your house and air conditioner pad into the grass. The usual recommendation is 6 ft from the house for drain spouts, this is a lot less water coming out so it might not need to go so far away, but far enough.

  • Good idea , - I'd suggest a variation of getting some hose that will fit outside OP's existing line. That way there's no male-male fitting in the line narrowing the internal diameter.
    – Criggie
    Commented Jul 15, 2023 at 0:07
  • Using male-male means there's a restriction in the tubing. Finding a tube with the same i.d. as the o.d. of the existing pipe should be a better option, as there's no pressure in that pipe.
    – Tim
    Commented Jul 15, 2023 at 11:02
  • Love the idea of cutting a piece of the line and using it as reference - thank you for the suggestion!
    – Den
    Commented Jul 18, 2023 at 17:27

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