Chlorine and Mesa's water

The City of Mesa takes pride in delivering safe drinking water to its customers. Chlorination, the process of adding chlorine to the water, is an important part of ensuring drinking water safety. 

Chlorine is added to the water supply for the purpose of disinfection. Disinfection kills or inactivates harmful microorganisms and germs which can cause illnesses such as typhoid, cholera, hepatitis and giardiasis.  Other bacteria, like the ones that cause Legionnaires' disease, are destroyed in the disinfection process. Since chlorine has been added to public water supplies the threats of water-borne illness and recreational water illness have been virtually eliminated.

Chlorine is also added for its "residual" properties. Chlorine remaining in the water supply is available to fight against potential contamination in water distribution and storage systems that might enter through leaks and pipe breakages.  Chlorination helps to stop nuisance growths in wells, water pipes, storage facilities and pipes. This is called "secondary disinfection."

Chlorine is a naturally-occurring chemical element found primarily as the chloride ion, a component of the salt that is deposited in the earth or dissolved in the oceans. Chlorine is an essential nutrient for plants and animals. 

Chlorine kills pathogens such as bacteria and viruses by bonding with and destroying their outer surfaces and breaking the chemical bonds in their molecules. When enzymes in the bacteria and viruses come in contact with chlorine, one or more of the hydrogen atoms in the molecule are replaced by chlorine. This causes the entire molecule to change shape or fall apart. When enzymes do not function properly, a cell or bacterium will die.


For more information about Chlorine