For almost 100 years now, chlorine gas has been the primary disinfectant used in treating municipal water supplies worldwide. Today in the United States, even with alternative methods being widely available, chlorine gas is still chosen as the primary disinfection method for more than 65% of all drinking water. Using chlorine gas for disinfection is a logical choice in that it is very effective and economical, and easy to operate and maintain. Many will also argue that chlorine gas is actually the safest disinfection method due to the fact that is it now almost always fed under vacuum, greatly reducing any chance of leaks. Although chlorine gas is a hazardous substance, most people do not know the facts and safety statistics of its use in water disinfection. Without this information many tend to overestimate the hazards of chlorine gas when comparing it to alternative disinfection methods such as sodium hypochlorite and calcium hypochlorite.
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