# How clean is condensation? **URL:** \ **Category:** Factual Questions\ **Created:** [August 8, 2023, 4:21pm UTC](https://boards.straightdope.com/t/how-clean-is-condensation/988256 "2023-08-08T16:21:39Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [August 8, 2023, 4:21pm UTC](https://boards.straightdope.com/t/how-clean-is-condensation/988256/1 "2023-08-08T16:21:39Z")
If I have a cold drink outside on a humid day, I get a lot of condensation on the can. If the can were thoroughly cleaned beforehand, would the collected condensation be potable? ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [August 8, 2023, 4:24pm UTC](https://boards.straightdope.com/t/how-clean-is-condensation/988256/2 "2023-08-08T16:24:51Z")
Yep. You’ve discovered the solar still. In this case, the solar “evaporator” is the environment. > **[Solar still](https://en.wikipedia.org/wiki/Solar_still)** > > A solar still distills water with substances dissolved in it by using the heat of the Sun to evaporate water so that it may be cooled and collected, thereby purifying it. They are used in areas where drinking water is unavailable, so that clean water is obtained from dirty water or from plants by exposing them to sunlight. > Still types include large scale concentrated solar stills and condensation traps. In a solar still, impure water is contained outside the collector, where it is evaporated by ... Now, if it were rain, which is also condensed atmospheric water vapor, you’d have to deal with the fact that each drop has a condensation nucleus, which may be a grain of dust or something else you may want to filter out first. ---
**Author:** ![burpo\_the\_wonder\_mutt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/burpo_the_wonder_mutt/32/365_2.png) [@burpo\_the\_wonder\_mutt](https://boards.straightdope.com/u/burpo_the_wonder_mutt)\ **Post date:** [August 8, 2023, 4:58pm UTC](https://boards.straightdope.com/t/how-clean-is-condensation/988256/3 "2023-08-08T16:58:13Z")
Wouldn’t it have your hand grime on it? ---
**Author:** ![Hypno-Toad](https://avatars.discourse-cdn.com/v4/letter/h/b2d939/32.png) [@Hypno-Toad](https://boards.straightdope.com/u/Hypno-Toad)\ **Post date:** [August 8, 2023, 5:00pm UTC](https://boards.straightdope.com/t/how-clean-is-condensation/988256/4 "2023-08-08T17:00:26Z")
> [@gnoitall](#): > > Now, if it were rain, which is also condensed atmospheric water vapor, you’d have to deal with the fact that each drop has a condensation nucleus, which may be a grain of dust or something else you may want to filter out first. This was the kind of thing I was wondering about. If the water would bring floating particulates in the air with it. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [August 8, 2023, 5:35pm UTC](https://boards.straightdope.com/t/how-clean-is-condensation/988256/5 "2023-08-08T17:35:03Z")
The vapor doesn’t contain anything but water. It’s mixed with the other gaseous constituents of air, but it’s all dissolved together in a big indistinguishable gaseous mixture. When the water condenses, it’s the only thing in a normal air mixture that comes out of vapor phase at that temperature, so the resulting liquid water doesn’t bring anything out of the rest of the atmosphere with it. At the instant it condenses, it’s about as pure as it can be. After that, it can begin to dissolve other water-soluable substances or mix with stuff it’s in contact with, like atmospheric gases or dust on the condensation surface, but that’s true of any liquid water anywhere. What you have is distilled water, which is as pure as you can get water without some moderately (or extremely) exotic purification technology. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [August 8, 2023, 5:44pm UTC](https://boards.straightdope.com/t/how-clean-is-condensation/988256/6 "2023-08-08T17:44:04Z")
> [@Hypno-Toad](#): > > This was the kind of thing I was wondering about. If the water would bring floating particulates in the air with it. You may notice that the air quality index, at least with regards to particulate matter, improves after a rainstorm. The condensation of the initial rain drop around a particle is just the starting point; the droplet also removes lots of PM from the air as it falls thousands of feet down to the ground. This works so well that it’s the mechanism of action in wet scrubbers for cleaning industrial exhaust gas streams: > **[Particle collection in wet scrubbers](https://en.wikipedia.org/wiki/Particle_collection_in_wet_scrubbers)** > > Particle collection in wet scrubbers capture relatively small dust particles with the wet scrubber's large liquid droplets. In most wet scrubbing systems, droplets produced are generally larger than 50 micrometres (in the 150 to 500 micrometres range). As a point of reference, human hair ranges in diameter from 50 to 100 micrometres. The size distribution of particles to be collected is source specific. > For example, particles produced by mechanical means (crushing or grinding) tend to be large (a... For condensate developing on your cold beverage can, it will only be collecting whatever PM happens to breeze by it. Which is to say, not much - no more than the free surface of the beverage inside the can itself.