Consuming filtered tap water provides substantial health and environmental benefits compared to bottled water, according to a study by the Barcelona Institute for Global Health (ISGlobal).
While a total switch to tap water would lower overall life expectancy, the findings show this to be the preferable option – particularly when a filter is used – due to the overall impact on the environment.
The research, published in Science of the Total Environment, aimed to provide objective data about three different water consumption choices: bottled water, tap water and filtered tap water.
The study authors used a novel combination of assessment criteria, combining a Life Cycle Assessment (LCA) on environmental impact with a Health Impact Assessment (HIA) on human health. They claim it is the first example of a study using this combination in an analysis.
Tapping into water treatment
The study comes amid a surge in bottled water consumption, which the authors attribute to perceptions on risk, taste, odor and lack of trust in public water companies.
“Tap water quality has increased substantially in Barcelona since incorporating advanced treatments over the last years,” says Cristina Villanueva, ISGlobal researcher and first author of the study.
“However, this considerable improvement has not been mirrored by an increase in tap water consumption, which suggests that water consumption could be motivated by subjective factors other than quality.”
One of these subjective factors is the perceived presence of chemical compounds in tap water, she notes.
“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.”
Results show 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 US$83.9 million per year due to the extraction of raw materials.
This would be approximately 1,400 times more impact in ecosystems and 3,500 times higher cost of resource extraction than the scenario where the whole population would shift to tap water.
Life expectancy and the environment
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 (which equals an average of two hours of lost life expectancy if spread equally among all Barcelona residents).
Adding domestic filtration to tap water would reduce that risk considerably, lowering the total number of years of life lost to 36. The study authors emphasize that despite the overall impact on life expectancy, switching to tap water still remains preferable.
“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,” says Cathryn Tonne, ISGlobal researcher and last author of the study.
“The use of domestic filters, in addition to improving the taste and odor 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, we know it is much lower than that of bottled water,” she concludes.
Fighting water pollution
In March, South Korean start-up Real Water developed a reusable bottle cap that filters out microplastics from water.
The invention comes following a recent study from Wageningen University and Research (WUR), the Netherlands, calculated that humans ingest about 0.0041 mg of microplastic particles a week – less than a grain of salt – and 12.3 mg in a lifetime.
