Chlorine in Tap Water Is Safe to Drink

There has been a lot of press recently touting new water filters for faucets, showers, and entire home systems. As a marketing tactic to increase sales of these products, advertisers have been overplaying an unsubstantiated risk associated with drinking water chlorination. They overlook the benefits of chlorine as an inexpensive and highly effective disinfectant and do not recognize that the regulatory limits for chlorine and disinfection byproducts were set following a thorough review of credible health data.

The Environmental Protection Agency (EPA) says most people don’t need to treat their drinking water at home to make it safe. If taste is the primary concern, an inexpensive pitcher, refrigerator or faucet attachment with a carbon filter will likely help. A shower filter may offer extra security for people “more vulnerable to the effects of waterborne illness” such as infants, the elderly or those with compromised immune systems.

However, many consumers don’t want their tap water unfiltered at the point of use. According to a Gallup poll released last year, pollution of drinking water is the top environmental concern for Americans. Many express worries about the risk of diseases, including cancer that can be associated with contaminants such as arsenic, chlorine and pharmaceuticals sometimes found in drinking water. But there is no real evidence to back up these concerns.

The primary purpose of having chlorine in the water is to destroy the bacteria and viruses that can enter a water system in many different ways. A chlorine residual provides the primary protection from these known and well understood pathogens. It is the only effective, large scale method for residual protection of drinking water. Although chlorine can react with organic material in water to create low level contaminants, these are closely regulated by the EPA.

The EPA requires treated tap water to have a detectable level of chlorine to help prevent contamination. The 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.” Only chlorine based disinfectants can provide lasting protection from waterborne diseases throughout the distribution system from treatment plant to the consumer’s tap.

Over 98 percent of U.S. water supply systems that disinfect drinking water use chlorine. In the U.S. we have depended on chlorine as our drinking water disinfectant for over a century. Public health officials heralded water chlorination as one of the greatest public health achievements of the millennium. The real danger, when it comes to chlorine, is eliminating its use.

For more articles about the safety benefits of chlorinated drinking water, please visit Safe Drinking Water.


Chris J. Wiant, M.P.H., Ph.D., is president and CEO of the Caring for Colorado Foundation. He is also chair of the Water Quality & Health Council.