Our house has a 3/4" PVC pipe coming out the side which drains condensation from the central air conditioning. It drips at what seems like a normal rate. Taking a wild guess, I'd say a gallon per day. The water lands maybe two inches from the exterior wall.

At my dad's suggestion, I just added flexible pipes to divert the water from our gutters away from the house. He also suggested I divert this drip. His concern in both cases is potential moisture problems in the basement.

  1. Is this amount of water worth diverting?
  2. If so, I'd want a flexible hose and a clamp to attach it. So far my searches only turn up hoses for interior use. Any clues what this would be called?


I think the amount dripping is actually more like 5 gallons a day (another wild guess, but it is actually a thin little stream rather than a drip).

  • Is this any more water than what would be present when it rains?
    – Fezter
    Jul 25, 2013 at 23:15
  • If you don't have existing water problems, I don't see how a gallon of water a day is going to cause any.
    – DA01
    Jul 26, 2013 at 0:44
  • @DA01 - I think I underestimated; revising my question. Jul 26, 2013 at 0:45
  • 1
    It sounds like you're just pulling these numbers out of the air. Put a bucket under it and measure it. But I agree with @JohnSmith that unless you have standing water or a very large wet patch it's probably not a big deal.
    – Hank
    Jul 26, 2013 at 3:32
  • I am not an air conditioning condensation expert but 5 gallons seems like a LOT. Also do use flexible hoses outside. Clamp on some PVC and drain out.
    – DMoore
    Jul 26, 2013 at 5:20

2 Answers 2


I've read a few sources on this and there seems to be some argument on what the best practice is. This thread at InspectorsJournal is similar and the conversation quickly shows that even most of these inspectors have different opinions when it comes to A/C drainage. A lot of the difference though, is geographic location of the home, and whether the ground around the drain slopes away from the house or is flat.

The example in the image below if from the EPA in their guide for moisture control around the foundation. Not all the guide will be useful and its not exactly your situation, but you can check it out here.

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If the water is not running away from your foundation and sitting stagnant against the it, I would drain the water. TodaysHomeOwner.com has a good article on possible solutions. Though the topic is for a drain directly from an exterior A/C unit, the principles should be the same.

If you can't extend your 3/4" PVC easily, exterior hose clamps and hoses should be available at your local home improvement stores. Most of clamps are stainless steel and should work fine. Plumping departments should have hose by the foot that would work as well.

  • It may be better to leave an air gap. Put a drainbox under the line and extend a hose from the drainbox away from the home. This will reduce the amount of pipe that can clog and potentially cause a backup of condensate into the home. Also take this time to verify or install an AC shutdown switch that will trigger if the line becomes blocked.
    – mfarver
    Jul 27, 2013 at 1:22

If your furnace is in the attic, this means the primary drain is clogged. its secondary drain is placed in a conspicuous location to inform you of something new or amiss. I have seen furnaces in garages that drain into a planter as described and there is no issues, it depends on where your unit is, where the condensate lines go, if its in the attic you have primary and secondary drains.

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