FAQ's about Chlorination?
Why is chlorine added to drinking water? Chlorine destroys disease-causing germs and waterborne disease germs.
What impurities will chlorination remove? Chlorination is a water treatment that destroys disease-causing bacteria, nuisance bacteria, parasites and other organisms. Chlorination also removes soluble iron, manganese, and hydrogen sulfate from water. There is no substitute for a safe and sanitary water supply. If your water supply becomes contaminated, elimination of the source of contamination is the most permanent solution. Continuous chlorination to kill disease-causing bacteria in contaminated water source should be a temporary measure used only until you can develop a new sanitary water supply. But it causes water to smell and taste very bad.
How is chlorine added to drinking water? Water treatment operators may chlorinate drinking water using either chlorine gas, liquid sodium hypochlorite solution (bleach) or dry calcium hypochlorite. Each of these disinfectants unleashes the power of chlorine chemistry to destroy disease-causing germs in water.
How does chlorine destroy germs in drinking water? Chlorine destroys waterborne germs by penetrating their slime coatings, cell walls and resistant shells. Chlorine either kills the germs or renders them incapable of reproducing.
Is chlorine in drinking water safe? A very small amount of chlorine added to disinfect drinking water is safe for consumption. Allowable chlorine levels in drinking water (up to 4 parts per million) pose "no known or expected health risk [including] an adequate margin of safety" while providing for "control of pathogens under a variety of conditions."
How to test your water? Most water testing for chlorination purposes is done to detect the presence of coli form bacteria. Coli form bacteria testing is used as an indicator of the possible presence of disease-causing bacteria. Tests for the presence of coli form bacteria may be made by the Most Probable Number (MPN) method or the Membrane Filter (MF) method. If no coli form bacteria are detected in a test, the MPN will be reported as and the MF as. If any bacteria are present, the number will be stated.
What are the advantages of Chlorination? Chlorination controls Disease-Causing Bacteria, Controls Nuisance Organism, and Mineral Removal.
What are the disadvantages of Chlorination? Nitrate Removal is not done by chlorine: nitrates are not removed from water by chlorination, Causes Smell and Bad Taste: in those cases an activated carbon or charcoal filter may be used to remove the chlorine from the drinking water. Chlorine changes the tastes and odor of water. Chlorination can also produce harmful by-products called Trihalomethanes (THMs) which are linked to incidence of cancer.
The Chlorination Process To chlorinate a water supply properly it is necessary to understand chlorine demand, free available chlorine residual and contact time.
How common is chlorine disinfection of drinking water? Chlorine is by far the most commonly used drinking water disinfectant in all regions of the world. Today, about 98 percent of water treatment systems use some type of chlorine disinfection process to help provide safe drinking water. The Environmental Protection Agency requires treated tap water to contain a detectable level of chlorine to protect against germs as it flows from the treatment plant to consumers’ taps.
How effective is chlorine against germs? Chlorine is highly effective against most disease-causing germs found in drinking water sources. The ability of chlorine to kill germs depends on both the concentration of chlorine in the water and the amount of time that the chlorine has to react with microorganisms (contact time). While chlorine quickly kills most waterborne germs, a few microorganisms, such as Cryptosporidium, are resistant to typical chlorination practices. Therefore, some water systems may require additional treatment steps to protect against particularly resistant pathogens.
What are disinfection byproducts? Disinfection byproducts, or DBPs, are chemical compounds formed unintentionally when chlorine or other disinfectants react with natural organic matter in water. The Environmental Protection Agency (EPA) has established science-based regulations limiting certain DBPs (particularly two groups of chemicals known as trihalomethanes and halo acetic acids) in drinking water. These standards have been endorsed by a broad range of organizations, including public health agencies, environmental groups and drinking water utilities. Most water systems do not meet EPA standards by controlling the amount of natural organic matter present in water prior to disinfection.
While DBPs should be reduced where possible, protection from germs remains the top priority. The World Health Organization strongly cautions that "The risk of illness and death resulting from exposure to pathogens in drinking water is very much greater than the risks from disinfectants and DBPs…Efficient disinfection must never be compromised."