Quote Originally Posted by cigarettes42
hey i just gotta quick question. how long does it take chlorine to evaporate out of water.
How long is a piece of string?

Depends on initial concentration, temp, solution pH, presence of other compounds in the water, ratio of surface area to volume, etc.

Reference Library/Applications:Industrial Wastewater - Inorganic Pollutant / Dechlorination with Hydrogen Peroxide

Here's a water-treatment paper about it.