The first treatment process is called primary disinfection. We carefully add measured doses of chlorine to water leaving the reservoirs to kill germs that may be present. The second treatment process is called residual disinfection. We add a mild and long lasting disinfectant called chloramine closer to the city and town systems to help keep the water safe while it is in the city and town pipes. Our reservoir water has low levels of dissolved minerals.
Soft water is good for laundry and shampooing.
But, it can also absorb metals from pipes. For instance, soft water can absorb iron from water mains or lead and copper from home plumbing. MWRA adjusts the water's chemistry so that the water absorbs less of these metals. We add soda ash to adjust alkalinity and carbon dioxide to adjust acidity. We also add fluoride to the water to promote strong teeth.