Can I Water My Plants WIth It?
by John Laumer, Philadelphia on 07.29.05
We've had a series of water use questions, all related to what readers might safely do with air conditioner or dehumidifier discharge water ("condensate"). Guess its hard to bring yourself to pour it down the drain when you're in the middle of an historic drought. Here are some short answers, written like a FAQ. Feel free to 'pipe in' with your insights.
Q: Can I drink it?
A1: Not if you want to be healthy. Condensate water is definitely full of bacteria, dust, pollen, and fungi. Besides, the inside of the tank is gross.
A2: Not unless you weirdly like to drink distilled water. The condensate lacks dissolved minerals to buffer and add flavor, is relatively acid, and tastes nasty.
A3: Not wise because, depending on what the chiller or air handler is made of, the acidity of the condensate will dissolve copper, aluminum, and possibly lead and zinc from solder joints and tubes. If you want trace metal supplements, take vitamins without the lead.
Q: Can I water my plants with condensate discharge water?
A1: Probably fine for houseplants, flowers, or perennials. I'd be especially hesitant to use for leafy vegetables, considering A3 (see first question).
A2: About half of all Americans get drinking water from groundwater well sources. Many of these people have excessively hard or iron or sulfer fouled water and use ion exchange technology to convert natural calcium salts to sodium salts that have a lowered tendency to congeal soap, or more "softness" as they say. Some water is naturally saline as well as hard. A sure sign of hard and/or saline water is that white crust that builds up on the soil surface or around the base of a house plant pot. Eventually, the increased soil salinity from adding highly softened water starts to rob the plant itself of water through a process called "osmosis". Using condensate discharge to water plants helps mitigate against this problem.
A3 Watering your perennial garden with highly softened water slowly builds up salinity until the next strong rain comes along. Doing this over a long droughty period ads stress. If you have condensate water at hand, it would be better to water the flowers with it than with saline tap water.
A4: Take a look at where your air conditioner condensate discharge line spills out on the ground next to your residence. Generally its close by the compressor. See if the surrounding plants and grass are vigorous. Are they fine? OK.
This is exactly the info I've been looking for! I couldn't even get anything from contacting Carrier (my AC manufacturer). Thank you very much.
The article talks about the inside of the tank being gross, but on my brand new dehumidifier is spotless, and the water is crystal clear. And if it wasn't cleaning the tank and the filter is a simple matter. Dust and pollen can easily be removed with a brita filter(actually I prefer pur), which would also add carbon to counteract the distilled taste.
My only concern are the pathogens and heavy metals. Some amounts of copper, zinc, and possibly aluminum(not sure), are beneficial, but obviously only a very small amount. Clearly any levels of lead and some other elements are bad, as is a significant(i.e. > than tap water) level of pathogens.
While this article brings up important points, it doesn't seem to have any facts or data to back it up. It would be nice if someone would do testing of the output water from dehumidifiers, including models that are new as well as several years old, and models with different materials.
You could filter it. But keep in mind that its not chlorinated so there is nothing at all to inhibit bacterial growth. Condensate has nutrients from the dust load so bacteria and mold can grow in that nice dark fertile place.
Filters vary widely in effectiveness and the good ones, like you'd use on a hiking trip, cost plenty to use. You're only looking at a few gallons per day at the very most; and,you've already paid, directly or indirectly, for the purveyors of your drinking water to chlorinated it and test to compare heavy metal levels against recommended max contaminant levels. These data are free to you by law.
TreeHugger does not do Consumer Reports type testing and hence is not in a position to evaluate risk with any depth. We do however, believe in not sweating the little stuff. With the opportunity to water some plants, that seems like enough, unless of course there's a major terrorist event and its the only water in the house and then who cares?