Disinfection with Chlorine
Frequently Asked Questions
Chlorination is the process of adding chlorine to drinking water to disinfect it and kill germs. Different processes can be used to achieve safe levels of chlorine in drinking water. Chlorine is available as compressed elemental gas, sodium hypochlorite solution (NaOCl) or solid calcium hypochlorite (Ca(OCl)2 1. While the chemicals could be harmful in high doses, when they are added to water, they all mix in and spread out, resulting in low levels that kill germs but are still safe to drink 2.
Safe drinking water
Your water company monitors water quality regularly to provide you with safe drinking water. Some people are more sensitive than others to chemicals and changes in their environment. Individuals who have health concerns should seek medical advice from their healthcare provider before contacting their local health department.
During dialysis, large amounts of water are used to clean waste products out of a patient’s blood. Dialysis centers must treat the water to remove all chemical disinfectants, including chlorine and chloramine, before the water can be used for dialysis. Home dialysis users should consult the machine manufacturer for instructions on how to properly treat their water before use.
The U.S. Environmental Protection Agency (EPA) allows drinking water treatment plants to use chloramine and chlorine to disinfect drinking water. Water system pipes develop a layer of biofilm (scum) that makes killing germs more difficult 5. Water providers may temporarily switch from chloramine to chlorine disinfection to help remove this scum layer.
Chlorine and chloramine are toxic to fish, other aquatic animals, reptiles, and amphibians 7. Unlike humans and other household pets, these types of animals absorb water directly into the blood stream 7. Don’t keep these animals in water that contains these disinfectants. Chlorine can be removed from water by letting it sit out for a few days or by buying a product at your local pet store that removes the chlorine. Ask your local pet store about methods of removing disinfectants from water for these pets.
The small amount of chlorine added to water will not affect other pets (such as mammals and birds) and can be used regularly for watering and bathing animals.
Plants are not harmed by water treated with chlorine.
- EPA. Drinking Water Treatability Database: Chlorine.External 2014.
- EPA. Basic information about disinfectants in drinking water: Chloramine, chlorine and chlorine dioxide.External 2013.
- EPA. The history of drinking water treatment. Cdc-pdf[PDF – 4 pages]External 2000.
- Water Research Foundation. Long-term effects of disinfection changes on water quality. Cdc-pdf[PDF – 320 pages]External 2007.
- EPA. Alternative disinfectants and oxidants guidance manual. Cdc-pdf[PDF – 346 pages]External 1999.
- EPA. Information about chloramine in drinking waterExternal. 2012.