Can You Use Dehumidifier/Air Conditioner Water on Plants?

If you use a dehumidifier (a common practice in basements worldwide and on all floors of houses in truly humid climates), you know that it produces a considerable amount of water that accumulates in a bucket that you have to empty periodically, sometimes even daily. Most air conditioners too produce water that has to be drained away.

In a world where excessive water consumption is a major concern, couldn’t you be reducing your water footprint by using this condensate for something practical rather than simply pouring it down the drain, something like — for example — watering your plants?

That’s the subject of today’s blog.


How A Dehumidifier Works

First, let’s look at how the average home dehumidifier works. Most reduce excessive humidity by refrigerating metal pipes. When exposed to humid air, the coolness of the pipes causes water to condense on them, a bit like the dew forms on foliage on a cool morning. The water pulled from the air, called condensate, flows into a recipient, called a condensate bucket, that must be emptied periodically. But where?

Most air conditioners operate in a similar fashion, but have a pipe that drains the water outdoors where it often simply goes to waste dripping on pavement or ciment.

But Is Condensate Safe to Use?

Dehumidifier and air conditioner condensate is not considered potable, as it can easily contain bacteria, fungi and other microorganisms that can build up in the pipes or condensate bucket. Likewise it may contain trace metals leaching from the metal parts of the condenser. Also, the air in our homes is often highly polluted and some of the undesirable air particles are likely to find their way into the condensate. So, for all these reasons, you definitely won’t want to drink it. Besides, condensate is demineralized, something I discuss below, and demineralized water has a flat taste most people don’t appreciate.

That said, dehumidifier and air conditioner condensate is not so contaminated that it can not be used for other purposes. It is considered to be “gray water”: water that insufficiently pure for human consumption, but that doesn’t require any special treatment to be used for other purposes.

Thirsty Plants

One obvious way of using condensate is for watering plants. Still, it is probably best to avoid using it on edible plants. Admittedly, the risk of contamination is minimal, especially if you apply the water to the soil, where microbes will quickly decontaminate it, rather than to foliage, and if you also rinse your plants before consuming them, but still, why take a chance? There are countless other types of plants you can safely water with condensate and that won’t end up in your plate: flower garden plants, container plants, houseplants, shrubs, trees, lawns, etc.

Carnivorous plants adore demineralized water! Photo: Valugi.

Demineralized Water

As mentioned above, condensate is demineralized. That is, unlike well water or tap water, it contains essentially no minerals that plants can use for their growth. Thus, it is pretty much the equivalent of distilled water, but with a few possible contaminants: let’s call it “gray distilled water”.

You can use it to water plants that won’t tolerate mineralized water, such as carnivorous plants, as well as plants that react badly to the chlorine found in  treated water, such as dracaenas (Dracaena spp.), marantas (Maranta spp.) and spider plants (Chlorophytum comosum).

Other Uses

Strangely enough, there is life beyond gardening and there are lots of other ways of using dehumidifier and air conditioner water: use it to flush the toilet, to wash cars and windows, to fill your iron, to add to your washing machine, etc.

Recycle reuse reduce: using dehumidifier/air conditioner water does it all!

5 comments on “Can You Use Dehumidifier/Air Conditioner Water on Plants?

  1. Gee, I would not have given it any thought. I give my garden much worse. We do not worry about this anyway, since we have no use for dehumidification.

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