How Much Water From AC Condensation Drain?

If you’re looking for ways to get free water for your garden or fountain, you should consider using the condensation from your home air conditioner. During the drought in California, lots of homeowners put tons of effort into saving water, and harvesting the moisture being drained out of your AC unit could be a great way to do just that.

How much water can you actually get from an AC condensation drain? I decided to do a real-world test and find out!

My AC Condensation Experiment

To measure how much water you can actually get from the air conditioner, I set up a measuring cup to catch the condensation while the AC was running.

After three minutes, I had collected almost exactly one hundred and fifty milliliters. Multiplying that by twenty, I estimated that the system was producing about three liters per hour–or slightly less than a gallon per hour.

Measuring my AC system’s output

My thermostat records how long I run my air conditioner, and I determined that I typically run it for three and three quarter hours a day. That means I’m getting a little over three gallons of water a day from the AC drain. While this isn’t a huge amount, it’s still enough to water some plants or top up a fountain.

This was on an 1,800 square foot house with a modern AC unit in California’s dry summer climate.

Factors Affecting Water Production

The amount of water produced by the AC unit also depends on the humidity inside the house. If it’s more humid in the house, the AC might produce more water as it takes out the moisture from the air.

If I do something like cooking that generates steam, that moisture could be pulled out of the air by the AC, potentially producing even more than a gallon per hour.

I’m going to continue to look into ways to automatically use this water for something helpful in the garden. It’s something that’s being generated anyway, so in the middle of a drought, you can still have no impact on the environment by harvesting this water.

One note: don’t drink the water from your AC system! It could contain bacteria. But watering non-edible plants is likely fine.