Used to kill life forms in the water, chlorine is a recognized carcinogen.
We are now entering into a period of increased water shortages. As reservoirs lower, water suppliers add more chlorine. This is because the number of micro-organisms in a reservoir do not decrease as water levels drop. They simply become more concentrated. Dosage will be lifted above recommended maximums due to the necessity of containing disease through micro-organism increases. During our last local drought, I could even smell chlorine gas from outside taps.
Chlorine in drinking water has been linked to increased incidence of bladder and rectal cancers by Harvard University and the Medical College of Wisconsin.
Chlorine is also linked to body protein damage. It causes dry skin and hair, and burns the eyes. If you suffer from asthma, sinus problems, allergies, skin rashes or emphysema chlorine in your water may well exacerbate your condition.
Chlorine kills bugs, but it also reacts with the organic matter in water, creating potentially toxic new substances. One such substance, trihalomethane, is far more carcinogenic than chlorine itself.
The USA EPA labels Mutagen X another chlorine byproduct and seen as the 'single largest contributor' to the ability of municipal water to cause genetic mutations.