I agree with
Ch4rlie. Perhaps it's the nerd in me but I really need data as well, especially given a mistake can be a catastrophe. In many instances though all we have is anecdotal information and we must extrapolate from it with a good deal of license...and risk.
The following is somewhere between anecdotal and a full scientific analysis but it does correlate with the LA water authority's recommendations
as well as his own measurements of both the chlorine and chloramine levels after 4 different removal methods, not the least of which is evaporation by Momchil:
There have been studies done on this in that in some locales, the use of chloramine mandates some form of removal or negation to be safe for fish.
Here in Los Angeles, the chloramine is about 3PPM-4PPM which would be fatal to mnay fish. Chloramine too can be negated by boiling but it is quite stable and needs a good deal of boiling to be removed sufficiently.
Evaporative and ultraviolet methods can accelerate this and while VERY effective on
chlorine, it's still rather impractical for chloramine. UV can greatly accelerate this though, sometimes to it's own detriment.
(
In LA, many public swimming pools are covered in part to prevent the UV from degrading the disinfecting action of the chlorine/chloramine as the UV breaks it down (although nowadays adding Cyanuric Acid to pools is commonplace to prevent UV light from breaking down chlorine in pools).
A series of tests were performed by Momchil where he found that 2PPM of Chlorine will take up to 110 hours to evaporate from 10 gallons of standing water.
Ultraviolet light, water circulation, and aeration will speed up the evaporation process dramatically though.
Boiling reduces this time from 110 hours substantially. Chlorine will dissipate 1PPM in about 4 minutes HOWEVER chloramine requires boiling for some 60 minutes for the same degree of reduction.
(Boiling is
not a linear method for removal of the chlorine compounds as they dissipate logarithmically positive over time-so dissipation accelerates the longer you boil it)
On average, it takes 4X the amount of time to dissipate chloramine vs chlorine.
(the water was circa 7.5pH during the tests).
Momchil then goes on to quantify the evaporative removal of 1PPM of Chlorine and 1PPM of Chloramine from 10 gallons of water:
Undisturbed Water-Chlorine-Chloramine:
55 Hours-173 Hours
Agitated Water-Chlorine-Chloramine:
10 hours-70 hours
Agitated and Aerated Water-Chlorine-Chloramine:
9 hours-67 hours
Boiled Water-Chlorine-Chloramine:
4 minutes-65 minutes
It's not easy to find studies or scientific data on this topic but I thought Momchil's findings here were quite interesting and the chart is excellent:
Free Chlorine to Degass from Tap Water