The environmental impact of bottled water is up to 3,500 times higher than tap water, according to a new study.

The consumption of bottled water has been increasing sharply in recent years on a global scale, due to the perceived presence of chemical compounds in tap water.

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The study, led by the Barcelona Institute for Global Health (ISGlobal), was aimed at providing objective data about three different water consumption choices: bottled water, tap water, and filtered tap water in the city of Barcelona.

“While it is true that tap water may contain trihalomethanes (THM) derived from the disinfection process and that THMs are associated with bladder cancer, our study shows that due to the high quality of the tap water in Barcelona, the risk for health is small, especially when we take into account the overall impacts of bottled water,” ISGlobal researcher Cristina Villanueva said.

The results, published in the journal Science of the Total Environment, showed that if the whole population of Barcelona decided to shift to bottled water, the production required would take a toll of 1.43 species lost per year and cost $83.9 million per year due to extraction of raw materials.

This is approximately 1,400 times more impact in ecosystems and 3,500 times higher cost of resource extraction compared to the scenario where the whole population would shift to tap water, the researchers said.

In this sense, the results estimate that a complete shift to tap water would increase the overall number of years of life lost in the city of Barcelona to 309. Adding domestic filtration to tap water would reduce that risk considerably, lowering the total number of years of life lost to 36, the study showed.

“Our results show that considering both the environmental and the health effects, tap water is a better option than bottled water, because bottled water generates a wider range of impacts,” ISGlobal researcher Cathryn Tonne said.

“The use of domestic filters, in addition to improving the taste and odour of tap water, can substantially reduce THMs levels in some cases. For this reason, filtered tap water is a good alternative. Even though we didn’t have enough data to measure its environmental impact fully, we know it is much lower than that of bottled water,” she adds.

However, the authors acknowledge that domestic filtering devices require adequate maintenance for proper performance and to avoid microbial proliferation.