Since the 1850s, chlorine has been used as a disinfectant to kill harmful bacteria in water itself or the pipes that transport it. It has helped end a number of major threats to public health. Although chlorine in water is essential at the treatment plant and in the water distribution system, it is no longer necessary once the water reaches your home.
While chlorine is vital for stopping the spread of disease, its benefits come at a price. Chlorine tastes and smells bad. It dries skin and hair, fades clothes (bleach is made of chlorine) and can dry out the rubber seals in appliances, shortening their lives.
And now many municipal water supplies have switched from chlorine to chloramines to disinfect and kill germs in drinking water. Chloramines are most commonly formed when ammonia is added to chlorine to treat drinking water. The use of chloramines is intended to provide longer-lasting water conditioning as the water moves through pipes to your home.