A new study has sounded the alarm about ordinary drinking water, warning that it may contain toxic cancer-causing ingredients. California researchers analyzed hundreds of water samples, including 603 tap, 100 bottled and 111 household treated water samples, to gain a better understanding of the quality of what we drink.
Shockingly, their study found that in the San Francisco Bay Area, all “three drinking water options had potential health risks.” This is primarily due to the presence of “trihalomethanes” (THMs) – a common byproduct of water disinfection with chlorine.
Although this treatment process has undeniable benefits to public health, such as preventing the spread of disease through waterways, long-term exposure to THMs has been linked to several adverse side effects. According to the HSE, this includes an increased risk of cancer and an increased chance of kidney and liver damage.
The authors of the new study wrote: “Alternatives to tap water, including household treatment of tap water and bottled water, are growing in popularity, but data on their water quality are limited. This is the first large-scale study to compare water quality from consumers’ realistic drinking water options of bottled water, tap water and tap water treated in households.”
While the “potential toxicity” in all three water sources was primarily due to THMs, tap water was shown to have a “significantly higher average toxicity.” At the same time, there were no significant differences between the potential toxicity of tap water treated in households and bottled water.
The researchers argue that this shows that bottled water “is not a better alternative to tap water if household treatment is possible” – especially since it often comes with more significant environmental and economic costs. “Ongoing aesthetic issues and potential toxicity [household-treated tap water] could be addressed by designing for the problems identified at the household scale, perhaps in collaboration with water systems,” they added.
Although this study focuses on San Francisco, there have also been countless concerns about the quality of tap water in the UK. In 2023, a substance found in hundreds of thousands of drinking water samples in England was classified as carcinogenic by the World Health Organization.
Perfluorooctanoic acid (PFOA), which belongs to a group of 10,000 compounds commonly referred to as ‘forever chemicals’, was detected in 11,853 samples from drinking water sources in 17 of 18 water companies in England. PFAS are used in a wide variety of products, such as food packaging, clothing and cosmetics.
PFOA and another member of the family – perfluorooctanesulfonic acid (PFOS) – are largely banned. However, they are said to remain in the environment due to persistence.
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