hi guys, i know something about math and physics and a lot about electronics and signal processing, but chemistry is the natural science that i have always been weakest about. first, how do most cities chlorinate their water? i presume they mix in some solid or liquid chemical that has Cl as part of the molecule. what are the other elements? do they precipitate out (before exiting the water treatment plant) or is there a lot more than the Cl in the tap water? i was told that, if you put chlorinated tap water into an uncovered pitcher and let it sit several hours, that much of the clorine will come out of solution and dissapate in the air, much like CO2 will in soda that has been opened and left sitting in air of about 1 atm. is that true? i presume, if the above is true, that after allowing Cl to escape, there will be less of it left in the water and if that is passed through the Brita filter, the filter will possibly last longer and maybe the filtered water will have even less chlorine in it than if the tap water was applied to the filter immediately after coming out of the tap. is this the case? thanks for replying with accurate info.