What Do You Know About the Water You Drink? Reflections on World Water Day

9% of the people in the world today do not have access to clean drinking water, a situation that leads to over 500,000 deaths from diarrhoea every year

The World Health Organisation estimates that 9% of the people in the world today do not have access to clean drinking water, a situation that leads to over 500,000 deaths from diarrhoea every year. At the same time, half of the people living in Barcelona drink only bottled water, even though it is much more expensive water from the tap and has a very negative impact on the environment. Is this a meaningless fad? Is it the result of rapacious business interests? Is it a question of taste? Could it affect our health?

54% of the city’s population in Barcelona prefers to drink bottled water and 7% use bottled water in cooking

The consumption of bottled water is growing at a frenetic pace across the globe in parallel with improvements worldwide in access to clean drinking water. As a country, Spain is one of the top ten consumers per capita of bottled water in the world, and Barcelona is no exception. Data relating to 2006 showed that 54% of the city’s population prefers to drink bottled water and 7% use bottled water in cooking on a regular basis. Bottled water is between 240 and 10,000 times more expensive than tap water. It requires between 1,000 and 2,000 times more energy to produce (mainly due to bottle manufacture and product transport) and it generates tons of plastic waste that has disastrous consequences for the environment.

Bottled water is between 240 and 10,000 times more expensive than tap water. It requires between 1,000 and 2,000 times more energy to produce

What is the reason for this high consumption of bottled water? The powerful bottled water industry has used advertising to promote the message that, as well as being purer and healthier, bottled water also tastes better than tap water. Studies carried out in different parts of the world report that taste is one of the reasons most often cited for choosing bottled water. The same studies report that the type of water consumed in a population varies according to individual characteristics, such as age, sex, and socioeconomic status.

In Nou Barris, only 27% of the population regularly drank bottled water, while the percentages for the Ciutat Vella and Sants-Montjuïc areas were 74% and 75%

In Barcelona, the type of water people drink is also associated with demographic and socioeconomic differences: in 2006, 59% of people with a third-level education habitually consumed bottled water as compared to 47% of people with a lower educational level. However, apart from these personal factors, much more significant geographical differences were detected in Barcelona: in the Nou Barris district, only 27% of the population regularly drank bottled water, while the percentages for the Ciutat Vella and Sants-Montjuïc areas were 74% and 75%, respectively. These geographical differences reflected differences in the characteristics of the tap water supplied in the city. About 7% of the city’s population receives water from the river Ter (including the Nou Barris district) and 16% is supplied by the Llobregat river (including the Ciutat Vella neighbourhood). The rest of the city is supplied with a mixture of water from both rivers. Water from the Llobregat has always contained higher levels of dissolved organic matter and salts (chloride and sodium) than the water from the Ter. These chemical differences can affect the organoleptic characteristics of the tap water and give rise to differences in the taste of the water supplied in different neighbourhoods.

The variations in the levels of salts also cause geographical differences in the levels of trihalomethanes found in the water. Trihalomethanes are chemical compounds that form as a by-product of chlorination, a process used to purify and disinfect drinking water.  We are not only exposed to these compounds when we drink the water; exposure also occurs through inhalation and skin contact when we shower, wash dishes or use swimming pools. In ISGlobal, we are studying how the by-products of chlorination can affect human health: for example, whether they represent a cancer risk or cause adverse reproductive outcomes. There is consistent evidence that lifetime exposure to high levels of trihalomethanes in water is associated with an increase in bladder cancer in men. The evidence relating to other types of cancer, such as cancer of the colon, is less consistent.

The quality of the water in Barcelona has changed noticeably since 2009, when improvements were implemented in the process used to purify and disinfect the water from the Llobregat river

The quality of the water in Barcelona has changed noticeably since 2009, when improvements were implemented in the process used to treat the water from the Llobregat river, substantially reducing and standardising the levels of salts and trihalomethanes in the city’s water supply. Data from the latest Health Survey currently being carried out by the Public Health Agency in Barcelona will provide data on whether regular consumption of bottled water in the city has declined, whether the differences between neighbourhoods have decreased, or  whether the growth in bottled water consumption is unstoppable.

On 21 March we will be talking about all these issues in a workshop-debate entitled “Do you know what’s in the water you drink?"

But are we able to distinguish between waters from different sources? The scant scientific evidence, which comes from the United States of America, indicates that the general public is not usually able to differentiate between tap water and bottled water. However, since the chemical and organoleptic characteristics of tap water and bottled water vary from place to place depending on the brand, there is no universal answer to this question.

On 21 March we will be talking about all these issues in a workshop-debate entitled “Do you know what’s in the water you drink?” at the Centre Cívic del Surtidor in Barcelona. The event is part of AiguArt, a cycle of activities organised by a diverse  group in Barcelona that includes La Fábrica del Sol and La Casa del Aigua de Trinitat Nova, among others. The workshop will take place on Tuesday 22 March to mark World Water Day.  It will include a blind tasting of different waters to see whether we are able to  distinguish between tap water, bottled water and filtered water, solely on the basis of taste.

References

Gómez-Gutierrez, A., Navarro, S., Masdeu, J., Gracia, J. 2012. La qualitat sanitària de l’aigua de consum humà a Barcelona. Barcelona: Agència de Salut Pública de Barcelona.

Villanueva CM, Cordier S, Font-Ribera L, Salas LA, Levallois P. Overview of Disinfection By-products and Associated Health Effects. Curr Environ Health Rep. 2015 Mar;2(1):107-15.