We have a moisture problem in the basement, and are trying to combat it with a dehumidifier. Despite my region being in drought, the humidifier's reservoir sometimes fills up twice in a day. The basement has no floor drain or laundry sink, but it does have our HVAC system, which was installed with a condensate pump. The contractor ran the drain hose for the condensate pump in a way that makes it difficult to add an additional hose, but I thought I might be able to drain the dehumidifier with the existing condensate pump.

Would it be safe or wise to run the drain line from the dehumidifier into the reservoir of a the furnace's condensate pump?

  • You might want to drain the dehumidifier to plants if you are having a drought and excess moisture in the basement at the same time... If the HVAC is a combustion appliance, you don't want that condensate on plants.
    – Ecnerwal
    Commented Sep 7, 2016 at 3:03

2 Answers 2


It seems both sources of water are low-flow resulting from condensation (one incidental, one deliberate) so you shouldn't challenge the condensate pump. I'd do it.


Aside from the issue of water volume, consider the chemical composition...

If your HVAC system is an air conditioner, then the condensate it produces is no different at all than the water produced by the dehumidifier. The cooling coil in the A/C unit is, in fact, dehumidifying as a side-effect (*). So water from the dehumidifer should be chemically indistinguishable.

If the HVAC condensate is from a furnace or boiler it would be somewhat acidic (a normal result of combustion). By adding water from the dehumidifier you would actually be diluting the acidity which would be harmless and possibly even helpful. Certain materials are more sensitive to acidity (like older metal, non-plastic drain piping) and in the worst case could be damaged. So diluting it could prevent that.

(*) The act of cooling air will often dehumidify unintentionally although central A/C could also be run to dehumidify according to a humidity sensor.

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