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