Dew Harvesting

What is Dew Harvesting?

Dew Harvesting is simply taking advantage of water vapor in the atmosphere to harvest clean and potable water through condensation, a passive process that allows water particles to return to the earth in a pure form.

The top photo features a roof dew harvester, and the bottom photo shows another technique.

We tried our own dew harvester in Cary. Check out the photos here.

Dew Harvesting IN BRISBANE!

It seems that the dew harvesting industry has shifted to focusing on rooftop harvesting. I even found this quote from Brisbane city councilman Norm Wyndman who has a rooftop harvester which harvests from an area of 400 square meter area, "On a good night, I get up to 70-80 liters of dew, on a bad night, there's absolutely nothing, but it generally evens out to about 60 liters of dew an evening.”

He also said that dew harvesting works best on metal roofs. "A tile roof generally has an absorbent factor which takes that dew off the roof, so you miss out on 75 per cent of it."

Dew harvesting is especially advanced in France, because they have slippery paint that allows the dew to slide into containers more easily, and they have their roofs at right angles.

Photo source: http://www.rain-barrel.net/dew-harvesting.html

A Detailed Explanation

Most dew harvesters are made from either plastic,(black vs. white) which seems to be the most promising, or aluminum.

Over night the dew harvester is cooled below the dew-point of the surrounding humid air.  When this occurs some of the dew in the air condenses on the harvester’s surface.  The harvester is slanted from the horizontal to prevent draining by gravity.

A Diagram of Dew Harvesting

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