I only use water filtered through a double stage filter; first a 5 micron and then a 1 micron carbon filter. This is supposed to remove about 90% chlorine. I generally only put water in them that has iodophor in the water. The water doesnt stay in their long; I try to keep beer in them!

So far I have not noticed any damage and I would think with that small of chlorine to treat the water there would be no problem.