New research has sounded the alarm over ordinary drinking water, warning it may contain toxic cancer-causing ingredients. Californian researchers analysed hundreds of water samples, including 603 from the tap, 100 from bottle water and 111 household-treated tap water, to get a better grasp on the quality of what we’re drinking.
Shockingly, their study found that all ‘three drinking water options had potential health risks’ within the San Francisco Bay Area. This is primarily due to the presence of ‘trihalomethanes’ (THMs) – a common by-product that comes as a result of disinfecting water with chlorine.
While this treatment process has undeniable benefits for public health, such as preventing the spread of diseases through water systems, prolonged exposure to THMs has been associated with a number of adverse side-effects. This includes an increased cancer risk and a heightened potential of kidney and liver damage, according to HSE.
Authors of the new study wrote: “Alternatives to tap water, including household-scale treatment of tap water and bottled water, are increasing in popularity but information regarding their water quality is limited. This is the first large-scale study comparing the water quality of the realistic consumer drinking water options of bottled water, tap water, and household-treated tap water.”
While ‘potential toxicity’ in all three water sources were primarily attributed to THMs, tap water was shown to have a ‘significantly higher average potential toxicity’. Meanwhile, there were no significant differences between the potential toxicity of household-treated tap water and bottled water.
Scientists claim this shows that bottled water is ‘not a superior alternative to tap water where household treatment is possible’ – especially when it often comes at a more significant environmental and financial cost. “Persistent aesthetic issues and potential toxicity in [household-treated tap water] could be addressed by designing household-scale treatment to specifically address identified issues, perhaps in partnership with water systems,” they added.
Although this study is centred on San Fransisco, countless concerns have also been raised 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 categorised as carcinogenic by the World Health Organisation.
Perfluorooctanoic acid (PFOA) – part of a group of 10,000 compounds commonly referred to as “forever chemicals” – was detected in 11,853 samples in the drinking water sources at 17 of 18 England’s water companies. PFAS are used in a wide range of products including food packaging, clothing and cosmetics.
PFOA and another member of the family – perfluorooctanesulfonic acid (PFOS) – have largely been banned. However, they reportedly remain in the environment due to their persistence.
