chlorine in tap water is fairly unstable. If you fill a container and leave the lid off all night all traces of any chlorine residual should be gone. With bottled "spring water" there is really no guarantee that you aren't getting the same water you get from your tap (and sometimes are!!). Never use de-ionized, distilled, or reverse osmosis water as some scientists believe that this will actually leach minerals from your body, based on the principles of osmosis. The majority of minerals utilized by the body are from the water we drink. This typically applies to humans but probably applies to reptiles equally.