New research undertaken by scientists from the Barcelona Institute for Global Health (ISGlobal), a center supported by the “la Caixa” Foundation, affirms that the better option for individual water consumption considering both environmental and health impacts is tap water.
Bottled water consumption saw a dramatic increase in the last few years globally. Earlier research links this trend to subjective factors such as taste, odor, lack of trust in public tap water quality, risk perception and marketing by bottled water companies.
The research carried out intended to provide objective data about three different water consumption choices — bottled water, tap water and filtered tap water. The findings were published in the Science of the Total Environment journal.
The scientific research was carried out in association with the Group of Environmental Engineering and Microbiology (GEMMA) of the Universitat Politècnica de Catalunya·BarcelonaTech (UPC).
Mostly environmental and health impacts are analyzed separately owing to the varied techniques implemented and resulting outcomes. Environmental impacts are analyzed using Life Cycle Assessment (LCA), while human health impacts are assessed with Health Impact Assessment (HIA). The current research, for the first time, combined LCA and HIA in the same analysis, thereby trying to overcome the methodological barrier.
The quality of tap water mostly varies between cities or countries, and the researchers focused on the city of Barcelona due to the robustness of available data. The Life Cycle Assessment was carried out using specific software and a method called ReCiPe, that permitted the scientists to assess the damage to ecosystems and resource availability.
The method also allowed the estimation of indirect impacts on human health resulting from the manufacturing process of bottled and tap water. The Health Impact Assessment utilized data on levels of chemical compounds in water supply and water consumption patterns from the Barcelona Public Health Agency.
The findings revealed that if the whole population of Barcelona decided to shift to bottled water, the production carried out will cost 83.9 million USD per year due to the extraction of raw materials and take a toll of 1.43 species lost per year. This is around 1,400 times more impactful in ecosystems and 3,500 times higher the cost of resource extraction when compared with a scenario in which the whole population shifts to tap water.
Tap water quality has increased substantially in Barcelona since the incorporation of advanced treatments over the last years. 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.
Cristina Villanueva, Study First Author and Researcher, Barcelona Institute for Global Health
“One of this subjective factors is the perceived presence of chemical compounds in tap water. 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,” added Villanueva.
In this regard, the findings estimated that an entire shift to tap water can increase the overall number of years of life lost in the city of Barcelona to 309 (which is approximately equal to an average 2 hours of lost life expectancy if borne equally by all residents of Barcelona). Summing up domestic filtration to tap water will decrease that risk significantly, lowering the total number of years of life lost to 36.
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.
Cathryn Tonne, Study Last Author and Researcher, Barcelona Institute for Global Health
“The use of domestic filters, in addition to improving the taste and odor of tap water, can reduce substantially 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 impactfully, we know it is much lower than that of bottled water,” added Cathryn Tonne.
The researchers also acknowledge the fact that filtering devices require appropriate maintenance for effective performance and to evade microbial proliferation.
Villanueva, C. M., et al. (2021) Health and environmental impacts of drinking water choices in Barcelona, Spain: A modelling study. Science of The Total Environment. doi.org/10.1016/j.scitotenv.2021.148884.