Most Americans take water chlorination for granted. This is how the majority of municipalities ensure that their tap water won’t make people sick. After all, chlorine is very effective at killing waterborne microbes. That is why public health officials view chlorination as one of the most important tools in preventing infection. It is critical for protecting people from diseases such as cholera or typhoid.
Does Water Chlorination Have Any Downsides?
A new study suggests that chlorine forms toxic chemicals in the presence of phenols (Environmental Science and Technology, Jan. 6, 2020). Such phenols are common in water supplies. The source may be personal care products or pharmaceuticals that end up in waste water and may be incompletely removed during purification. Plastic water pipes may also shed phenols into drinking water.
The authors point out that
“chlorine reacts with organic and inorganic water constituents to produce a variety of disinfection by-products (DBPs) that pose potential health risks.”
They note that over 700 DBPs have been identified, including some known carcinogens. The researchers found that phenols from consumer products interact with chlorine to cause some of these potentially toxic chemicals.
How Important Is Chlorine?
Do we really need water chlorination? Although it is a good way to guard against water-borne infections, chlorination is not the only technique that is effective. European public health officials often use other measures including filtration, ozone or ultraviolet treatment to purify water. There is no indication that people drinking such water are more likely to suffer illness as a consequence.