Don't Drink the Water (From Your Dehumidifier): Essential Answer

Q: I wonder whether the water pulled out of the air by dehumidifiers is pure and drinkable. How does it compare to distilled water?

Asked by Bill Wachob, '69, from Eggertsville, N.Y.

My parents have a vacation home in Western Massachusetts, where the air is quite damp. Frustrated by frequent mildew infestations and the associated unpleasant smell, they bought two dehumidifiers to dry the place out (one of which is pictured at left). As a 12-year-old, I was very curious about these noisy machines, but drinking the water from their collection buckets never crossed my mind. Fast forward to today. Many of us are trying to find ways to avoid wasting water, and I'm happy to report that you can find productive uses for your dehumidifier water. However, please, please, please do not drink it!

Both dehumidifiers and air conditioners reduce the humidity level in indoor spaces. Not only can drier air improve personal comfort in humid climates, but it can also reduce the amount of mold, mildew and other organisms that thrive in moist environments. Dehumidifiers are best suited for mild humid climates (such as Western Massachusetts, where it's damp but not warm enough to necessitate air conditioning), and humid hot climates (such as Florida, where air conditioners don't remove all of the humidity in the air).

Just as a cold drink collects condensation from the surrounding air, most dehumidifiers use cold metal tubes to turn water vapor from a gas to liquid water. This "condensate" then collects in a bucket or drains out through a hose. According to the Environmental Protection Agency, stagnant condensate can harbor biological contaminants, including mold, mildew and algae, especially if the collection bucket isn't cleaned regularly. Moreover, the condensate can contain lead and other metal residues from the component parts of the dehumidifier. Unlike distilled water (see Nitty Gritty), dehumidifier water is never sterilized through boiling. In case you were still entertaining the thought, let me make it clear: do not drink the condensate! It is better to be thirsty than to be sick.

You don't necessarily need to pour it down the drain, though. Like other kinds of gray water (see Nitty Gritty), most dehumidifier condensate can safely be used for flushing toilets. Because of the presence of harmful bacteria and microorganisms, it's probably not a good idea to use condensate to water any plants you intend to eventually eat. For other plants, do a small test run to see how they respond, because you don't want to destroy your whole garden at once if they don't take to it.

If you're really intent on drinking water made from the air in your home, you can get a potable water device, designed specifically for that purpose. Otherwise, please restrict your drinking to the stuff from your tap.

Andy Martin, '02, received his joint MBA/MS from the Graduate School of Business and the Emmett Interdisciplinary Program in Environment and Resources inĀ 2010.