So, there's this pipe sticking out of the wall between my garage and the front porch. Occasionally, an amount of water seeps out of it, enough to pool eventually though I've never seen any water "running" out of it, unrelated to any weather, seems clear (though when the pool dries, there seems to be some residue left behind).

I have no idea what it might be draining from. There is nothing on the garage side of the wall (though the water heater/furnace is along that same wall in another corner, maybe 15' away).

Any input would be appreciated, and most importantly - does the draining indicate some problem that I need to deal with?

Thanks![enter image description here]1

Thanks to all who provided input. It looks like a lazy contractor pushed the drain line out the wall at the point of the concrete patio, instead of running it another 10' where it could have been pushed out the front-facing garage wall (where the drip would have landed on dirt).

I'll get a HVAC/plumbing guy to come and answer the question (what appliance is being drained, whether the amount draining indicates some kind of soon-to-be problem). But yes, management of any outflow will be dealt with via a planter of some kind, rather than redirecting the line at this late date.

For those who might be curious, I captured outflow for the last 7 hours (0630-1330): 26 oz of clear water, no visible residue. Over that period, used water heater (hubby ran a large bath, I took a long shower, ran dishwasher) and the furnace (relatively briefly after being off overnight). What that might tell anyone, I have no idea (!) but there it is.

  • Usually when a drain drains it's a good thing. The alternative is a leak or overflow somewhere else. You mentioned the furnace. Have you investigated that?
    – isherwood
    Commented Apr 2, 2019 at 18:45
  • I'm guessing the pipe is hidden inside the wall and can't be seen from inside? Also, does it only weep after the furnace or air conditioner has been running for a while? My guess is that is is simply a drain line for condensate from your furnace or A/C (natural by product of combustion and condensing). I would not let it drip on the concrete as it will leave unsightly water marks; that looks like a great place for a long planter box to sit. Commented Apr 2, 2019 at 18:50
  • Is there a water heater inside it could be the T&P line if not from a heating and cooling system.
    – Ed Beal
    Commented Apr 2, 2019 at 19:29
  • Mary, feel the water when it drips. If it's coldish, it's probably from the A/C and if it's warmish, probably the water heater. Depends on how long the pipe is and how fast it drips, but water holds it's temperature pretty well and it will start off very cold or very hot depending on the source.
    – JPhi1618
    Commented Apr 3, 2019 at 20:35

2 Answers 2


I would bet against this being the regular drain for the air conditioner/furnace. The A/C creates a lot of water, and only the most inept remodeler would allow that to drain on a finished porch like that.

I had almost the same situation in a house and the dripping pipe came from the water heater's temperature/pressure relief valve and that had to be replaced ($20, not bad). The other option would be that it is from the A/C but its the secondary "overflow" drain that drips when the main drain is clogged. These are sometimes placed in visible areas so that you can see them dripping.

To answer your last question, I would assume that yes, dripping from such a conspicuously placed pipe does indicate a problem that should be addressed.

  • I was thinking T&P also +
    – Ed Beal
    Commented Apr 2, 2019 at 19:31
  • @EdBeal, looks like a metal pipe, so that's my first thought. A/C tends to be PVC in my area, even the secondary drain.
    – JPhi1618
    Commented Apr 2, 2019 at 19:32

That looks like a condensate drain from your Air Conditioner or Heat Pump. When you chill air, condensation forms on the coils and must be safely removed from the unit, otherwise you get mold growing on it. typically this is piped out to some innocuous area of your exterior wall where it doesn't pose a nuisance. If this is going right out to your front porch, someone was being inconsiderate in the design. I would just get a bigger bucket or decorative "flower pot" for it, moving it now would involve tearing open the walls.

  • My bet would be the porch was added later and originally it simply drained into the land. Commented Apr 2, 2019 at 18:56
  • There ought to be a mysterious pipe sticking out of your AC/Heat Pump somewhere. If there is, you can verify the flow source, and perhaps find a better path for the pipe. Commented Apr 2, 2019 at 18:59
  • Ooh, good point about the porch being added later. That pipe may have originally been just watering the landscape...
    – JRaef
    Commented Apr 2, 2019 at 19:06

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