Are there DANGEROUS levels of chloroform in Flint water?

Are there DANGEROUS levels of chloroform in Flint water?

Over the last few months, it has repeatedly been asserted by some that there are dangerous levels of chemicals, such as chloroform, in Flint water heaters and showers.  Moreover, that prior testing conducted in Flint by Virginia Tech and others, has “focused on lead and copper only.” Both of these statements are false.

The water industry has known for 40 years, that chemicals such as chloroform are expected to form whenever chlorine is added to water.  Thus, the presence of chloroform is expected in all samples collected from a system using chlorine, as is the case in Flint and Detroit and many cities all over the United States.

The EPA and the water industry are concerned about these chemicals, and have a regulation designed to make sure that they are present in water at reasonably low concentrations.  This is called the total trihalomethane (TTHMs) regulation or Disinfection By-Products (DBP) regulation.  By controlling the levels of chloroform and other chemicals by regular measurement in the water distribution system, they are also reasonably controlled by extension, in consumer water heaters and showers.

When we went to Flint in August 2015, we did measure TTHMs and chloroform throughout the distribution system.  We reported at that time, that Flint was meeting Federal laws for TTHMs and chloroform.  We also collected a few samples of chloroform and TTHMs in cold and hot water samples, from homes/businesses on Detroit water and Flint water.  That data is presented in the table at the end of this article.  We did indeed find chloroform, but at levels similar to other U.S. cities, and well within normal expectations.  Continued monitoring of chloroform in Detroit water by EPA and others to the present day, has confirmed that there is nothing happening in relation to TTHMs since August 2015 that is outside of normal expectations.  If we hear or find problems with TTHMs, chloroform or DBPs, we would release those results immediately.

Most of our subsequent work has focused on lead, simply because the levels of lead in Flint water exceed Federal standards. All other parameters that we have been monitoring are within Federal standards, including chloroforms and TTHMs.

Legionella levels were high in some large buildings, as we have acknowledged, but unfortunately there are no Federal Laws currently regulating Legionella.  EPA, the city and state, are working aggressively to control potential legionella problems with chlorine and flushing.

 If chloroform is formed whenever chlorine is added to water, why don’t water utilities stop adding chlorine to water?

 The simple answer is that many, many people would die from waterborne diseases such as cholera and Legionella if utilities stopped adding disinfectant such as chlorine to water.  Hence, the relatively small risk arising from chloroform (and other similar DBPs) in water, is far outweighed by the large number of lives saved from killing dangerous microorganisms.  This is well understood and we link to a recent article on chloroform in drinking water that discusses this tradeoff.

TTHM Results from August 2015:


Q+A: Dr. Marc Edwards

4 thoughts on “Are there DANGEROUS levels of chloroform in Flint water?

  1. When EPA implemented the CWA in 1972, it set limits for bacteria in treated sewage and since this was a new requirement, sewage treatment plants started to disinfect there effluents with chlorine. THM’s and DBP are formed when organics are chlorinated and since treated sewage still has a lot of organic matter, the concentration of these compounds increased in open waters. Where this water was used for drinking water, it also increased their presence in drinking water. Earlier pre-chlorination processes to prevent odor and taste problems did not help either.
    In 1978, advised by CDC and GAO stating that disinfection of treated sewage did not prevent waterborn diseases and was damaging to the environment, EPA dropped the national disinfection requirements for treated sewage, but left this to individual states to either dropped this also or maintain the requirement. Most states (advised by the chemical industry) maintained this requirement, although some cities have converted their chlorine disinfection system, claiming the chlorine storage could be a target for terrorists, with other disinfection methods, like UV. Pre-chlorination as a water treament was also not any longer recommened.
    Since the urine in sewage is not required to be treated in sewage and quickly becomes ammonia, it, in contact with chlorine, becomes chloramine, another less effective but longer lasting disinfectant. However, also a chemical compound that is corrosive for copper and lead water lines.
    Another major concern that antibiotic bacteria become resistant for chlorine.
    Although EPA, in the early eighties, promissed to come up with measures to regulate the use of chlorine, it never did, so we keep living in an era that, when you can smell chlorine, you think that you are protected from bacteria, good or bad.

    • This is why people need to research, know the facts and hold agencies paid to protect us responsible. Its the same thing with the Lead and Copper Rule.

  2. Thank you for your consistent and accurate information, Marc and Sid.

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