I recently purchased a home that had been remodeled by the previous owners. They installed a new furnace and A/C unit in the basement crawlspace. Initially, the crawlspace was dry and everything seemed fine.

Now that it's warmer where I live, i've noticed heavy water build up coming from the A/C unit condensation line which is just a small tube that drains into the crawl space. This leads to water collecting at a low point (where there is no drain) and building up. This is coming both from a plastic tube in a plug in the drain pan and an unplugged outplet in the drain pan.

I've cleaned up the large standing water with a shop vac, and i'm catching the condensate in a bucket and emptying it daily. While this stops most of the water build up, i'd prefer a more automated solution.

The only nearby drain in the crawlspace is a sump pit.

  1. Is this a normal setup? I'm surprised this passed inspection if it's not.
  2. Should I have my A/C unit checked out? or is this just a drainage issue?
  3. Any recommendations on how to solve this? I'm not above PVCing this to the sump if that's an acceptable solution.

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  • Is routing the condensate drain to the sump an option for you? Jun 15, 2021 at 4:22
  • When you do sort out where to plumb the condensate, tighten (or seal with new Teflon tape) that white barbed fitting the hose attaches to so it doesn’t leak. Years of that can cause corrosion of the metal housing.
    – Tim B
    Jun 15, 2021 at 10:50
  • I'm okay with routing to the sump. I would need to double check about any local ordinances though. @Timb thanks for the note about taking care of that leak. Will do! Jun 15, 2021 at 15:16

2 Answers 2


Draining to the sump pit is a common choice.

Another method is to use a small, automatic condensate pump to lift the water up high enough that it can be directed to another drain.


WORTH THE READ: If drainage water from HVAC - or any source for that matter - needs to drain inside solid walls that it is especially difficult to put pipes through, AND if there is already the potential of a moisture level higher than desired (check with a pro on what moisture level is "too much" - for us it is higher than 47%) - consider (1) installing an interior full-perimeter French Drain, (2) assure the French Drain terminates into a collection tank (15-18" diameter, 18-24" depth, covered except for extermination drain pipe), and (3) install an electric sump pump in the collection tank that will pump the collected water (from all sources via the French Drain) through a flex or fixed pipe OUTSIDE the interior (crawl) space to a point at least 1-2 feet away from the structure. (installation of the sump pump will necessitate a grounded/GFI-protected outlet near the site of the pump. (use professionals for this and anything else you aren't good at if you make it a DYI project...it's worth the one-time expense for safety!!)

In my case, we had the french drain and pump system installed when we discovered an excessive moisture level during a rainy season, so when we had the HVAC in the crawl space (and in the attic) installed, we authorized the HVAC installers to run the pipes to the stone-filled existing French Drain, assuring that the HVAC drains emptied into the middle of the 12" wide stone area WITH an elbow on the end of the HVAC drain pipes aimed downward into the stone, and covered with vapor barrier (plastic sheet).

We went one step further with installing a dehumidifier in the crawl space, centrally located, with a drain pipe directly to the collection tank - with a modest down-angle assured on the dehumidifier drain pipe (Uber Important!). I clean the permanent dehumidifier intake filter 2x per year and check for any leakage on all the pipes annually. Again, you can pay a HVAC pro to do this when you have annual or semi-annual service done to your HVAC. Problem solved - permanently!

After reading some others' experiences with various treatments, I need to add this: Hint: If you install a dehumidifier, (1) close the vents – let the dehumidifier do its job without adding moist summer air from outside! (2) regularly check the humidity level in the crawl space. (I do this remotely with a digital remote thermometer that also displays humidity, I actually have 3-station viewing, so I can view the inside the house temp, as well as station 2 crawl space and station 3 outside temp and humidity). Each remote requires a “one-time” purchase of a transmitter, and you will have to change out batteries in the remotes and base unit – about once every 2 years.

  • Hi Jay, it is very difficult to read a solid block of text. Please edit to split into paragraphs and use the list feature for items. Aug 29, 2023 at 14:49
  • Thanks. Is that better?
    – Jay Blum
    Aug 29, 2023 at 15:18
  • This is an exact copy/paste of another answer. How many times you going to do that?
    – FreeMan
    Aug 29, 2023 at 16:51

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