Chlorine vs. Chloramines
In the United States, the Safe Water Drinking Act was created to provide safe drinking water for citizens. The Environmental Protection Agency was tasked with setting standards to carry out that goal. The EPA guidelines require that tap water at any faucet be treated in order to kill bacteria and harmful health contaminants. Specifically, the requirement is that the tap water should contain a minimal chlorine concentration of 0.2 parts per million. Municipalities have been using chlorine for decades, but quite a large number have recently switched to using chloramine instead.
Because chlorine breaks down over time, the chlorine concentration of the water that comes out of your tap will be lower than that put in at the water plant. Thus, the exact concentration at your faucet depends on how far you are from the water plant, how long it takes the water to travel from the water plant to your house, and how much chlorine is initially added.
A serious concern with the use of chlorine is that it can combine with certain organics (that may or may not be present in your water) forming trihalomethanes, a family of carcinogens. President Obama’s Cancer Research Panel released in 2010 urged all Americans to use a point of use drinking water system to better protect their families from water-borne diseases and cancer-causing agents in our tap water. Simply put, we want the chlorine in the water to kill bacteria, but we want to remove it right before we drink.
Consequently, many water companies have switched from using chlorine to using chloramine, thinking it is a safer option. But is it? Chloramine, a compound containing both chlorine and ammonia, is much more stable than chlorine. Water utilities often refer to chloramine as monochloramine.
Trihalomethanes (THMs) are disinfection byproducts that are formed when organic matter in the water combines with chlorine. THMs are also formed with chloramine disinfection but at a lower concentration, about 1/3 less than chlorine. Filtration for chloramine is very expensive compared to filtration for chlorine and is considered to be a less effective disinfectant than chlorine. The World Health Organization (WHO) says that "monochloramine is about 2,000 and 100,000 times less effective than free chlorine for the inactivation of E. Coli and rotaviruses, respectively."
Here are some interesting comparisons between chlorine and chloramine:
- Chloramine does not dissipate easily compared to chlorine. It has been known to cause and/or aggravate respiratory problems because its harmful ammonia remains in the air longer. A study from the Catholic University of Louvain in Belgium showed that an increase in asthma resulted due to exposure from chloramine in indoor swimming pool areas.
- Chloramine stays in the water distribution system longer than chlorine. Fish owners are finding harmful effects on their aquatic environments because negative chloramine byproducts cannot be boiled out or dissipated over time, as opposed to when chlorine is present in the water.
- Chloramine is more difficult to remove than chlorine.
- Some disinfection byproducts of chloramine are even more toxic than those of chlorine, such as iodoacids.
More studies have been done on the negative health effects of using chlorine as a water treatment option simply because more municipalities have used chlorine longer rather than chloramine at their facilities. As more cities are choosing chloramine over chlorine in search for a better health alternative to treating water, an increased number of studies show that chloramine may actually be worse than chlorine.
So, which method of disinfection does your city use? By law they must make the composition of your water available to you. Should you be unhappy with your city’s choice of disinfection method, the best option is to simply use a water filtration system right at your tap. There are many models to choose from, ranging from above the counter to under the sink to whole house designs. Be sure that the drinking water system you purchase is certified by NSF to remove chlorine and/or chloramine.
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