Sustainability Supplement: Being Sustainable - As Easy as Drinking a Glass of Water by Giulia Torri

The Sustainability Supplement is a series of research articles prepared by InnoEnergy Master’s School students throughout several European locations. The series provides opinions and commentary on various topics including energy resources, energy efficiency, sustainability and other topics of interest. Any opinions expressed in these articles are those of the writer and do not necessarily reflect opinions of the  by InnoEnergy or the ‌ 


Every day we read about the global energy issues that the world is facing. Thinking that such a big problem has to be tackled by governments and big companies is the easiest way to feel that we have no responsibility in this complicated challenge.


But are we sure that we cannot play an active role and become involved?


In our current society, every action we do involves an energetic consequence. Sometimes it’s not evident: it’s easy to forget about it, for example, while drinking a glass of water. But even a natural action like this one can be linked to a significant energy consumption, and the effects of this simple choice have important and different consequences.



 Table 1. Yearly bottled water consumption in EU countries

EU Country


[L per capita]










When talking about potable water, two main possibilities are available: tap water or bottled water. At first sight, the choice can appear irrelevant and often people do not care about it. In the European Union, the consumption of bottled water is significantly high  (see Table 1), with a yearly peak of 188.5 L per person in Italy [1].


Is it a forced decision?


The EU directives regulate the essential tap water quality standards through the analysis of 48 indicator parameters based on the World Health Organisation guidelines [2]. Every Member State has to fulfill the common conditions and can add more rigorous restrictions in order to ensure that it is safe and healthy for human consumption [3].


Therefore, the quality of tap water and bottled water in Europe is not a determining factor and the water we drink only depends on our personal choice.


Energy behind water

In order to understand how this choice is connected with energy, a practical example can be useful. Let’s analyse the environmental impact that a common inhabitant of a European town has as a result of making the simple decision to drink either bottled or tap water.


First, let’s consider the case of bottled water. The 1 L bottles are commonly made of PET (.Polyehtylene Terephthalate) plastic, whose lifecycle has an important energy footprint [4]


Initially, the bottle is produced from raw materials. During this phase, the highest amount of energy is consumed: every bottle requires around 4 MJ (Megajoules) to be processed [4]. This is the same amount of energy required to power a TV for 7 hours, charge a mobile phone for 265 hours or brew 10 espressos [5]. Before being bottled, water is treated and purified. This practice can be done through different methods, and the average energy needed is 0.01 MJ [4]. The next step of the process is bottling: bottles are cleaned, filled, capped and labelled by using automatic devices. Generally, around 0.014 MJ are consumed for this [4].


At this point, the bottles are ready to be sold, but this is not the end of the energy required for the bottles. Bottled water, as almost every product, is not only traded in the production areas but is also marketed to distant regions or countries. Consequently, an energetic cost due to the transport has to be calculated. It’s easy to understand that the specific value is strictly dependent on the distance traveled and the means of transport: plane, ship or vehicle consumptions are significantly different.


Thus, in the analysed case study, additional details have to be introduced: let’s suppose that the consumer lives in Madrid, and the bottled water comes from the Pyrenees. The hypothesis, considering the actual commercial networks, is plausible and optimistic if compared with the real average transport itineraries (Evian from France, San Pellegrino from Italy and Fuji from Republic of Fiji are only some examples of brands exported all over the world).


Supposing the transportation is held by an average .16 ton truck, 15,350 bottles would be transported for a distance of around 600 km, resulting in an energy footprint due to the use of fuel of 0.812 MJ per bottle [6][7][8]


The same . The important difference is easily explained with the wide range of vehicles, engines and fuel blends that can be used. To analyse a generic situation, the mean value of 1.513 MJ is chosen.calculation, carried out with the guidelines of a study formerly conducted, outputs a value of 2.184 MJ/bottle [4]


The last step of the energy use connected to bottled water is the cooling process. Often, before being consumed, water is stored in fridges for some days, involving an average consumption of 0.2 MJ [4]. In conclusion, the sum of all the consumptions reveals that every litre of bottled water utilises an amount of energy equivalent to 5.737 MJ.


On the other hand, tap water requires energy in the phases of water treatment and distribution; the average consumption per litre is 0.005 MJ [4].


Energy consumption

Generally, a person drinks 2 litres of water every day, which translates to 730 litres in a year.


Therefore, the yearly energy consumption connected to the simple 4188 MJ in the case of bottled water, and 3.65 MJ in the case of tap water: in the first scenario the energy used is more than 1100 times higher than in the second.action of drinking water is


Actually, the results obtained are quite difficult to understand if discussed in MJ, a unit of measure not easily quantifiable in our everyday lives. For this reason, a practical comparison can be useful to visualise the values.


Assuming that a common car has an  engine efficiency of 20% [8], that gasoline’s LHV (Lower Heating Value) is 44.4 MJ/kg [9], and that the average consumption is around 7 L/100 km [10], the mentioned values can be depicted in the following way:


  1. The energy consumed per year in the case of bottled water is the same provided during the combustion of 94.3 kg of gasoline. This amount of fuel could run a car for 1873.5 km.
  2. In the case of tap water, every year the amount of gasoline burned would be 0.08 kg, allowing the car to cover a distance of only 1.63 km.



The described results are surprising, but the the consequences are still far from over. In addition to the energy consumption, some environmental aspects have to be analysed. In fact, the utilisation of energy during all the mentioned processes (either electricity from the grid, combustion in industrial boilers or in truck engines) involve the emission of pollutants to the atmosphere. To evaluate the magnitude of the problem, it’s reasonable to refer to the amount of equivalent emissions of CO2


For what concerns bottled water, two phases have to be distinguished. The first one includes the production of the bottle and the bottling process. The fabrication of 1 ton of PET is associated to a mean emission of 3 tons of CO2 [11], therefore around 0.12 kg of CO2 are emitted for every 1 L bottle. Accurate information is not available on the following treatments (water purification, bottling, labelling, etc.); to include them in the evaluation, an approximation of the former value to 0.125 kg of CO2 can be acceptable based on the process’s energy use. The second polluting phase is the transport: as explained previously, for every single case the value varies significantly. Since the average truck emissions are around 0.35 kgCO2/km*ton [12], in this example every bottle is associated to 0.22 kg of CO





Economic expenses

The obtained values raise personal awareness and sensitivity towards the environmental issue. However, there is a more pragmatic factor worth considering: the monetary price associated with both choices.


Assuming that in Madrid the average cost of a 1 L bottle of water is 0.5 € [14] while the cost of tap water is 0.00155 € [15], the annual expenses are the following:


  1. Drinking bottled water costs 365 € annually.
  2. Drinking tap water costs in total 1.13 € annually.


The responsible choice

The results of the analysed case study highlight how it is possible to contrast the possible effects of this simple action from an energetic, environmental and economic point of view. In the majority of European territories, the decision is not influenced by the lack of water quality, but depends on individual habits.


Therefore, it is evident that, through every choice we make, we can take advantage of our personal responsibility by remaining critical of the consequences of our actions. Or we can remain indifferent.


However, we often feel discouraged, because we judge our role as marginal and irrelevant.


In this regard, the next time you will experience this sensation consider even the easiest thing you do – drinking water – can have major impacts.


And what if you multiply these results by all the years of your life, and for all the inhabitants of the world?


Then, being conscious of your real impact, choose.


By Giulia Torri 

In Collaboration with The CommUnity Post

Published on 30 June 2017




  1. Natural waters: The natural choice for hydration. European Federation of Bottled Water, Canadean statistics (2015). Available at:
  2. Gorchev, H. G. & Ozolins, G. WHO guidelines for drinking-water quality. WHO Chron. 38, 104–108 (2011).
  3. Environment. Legislation. The Directive overview. European Commission - Environment (2016). Available at:
  4. Gleick, P. H. & Cooley, H. S. Energy implications of bottled water. Environ. Res. Lett. 4, 14009 (2009).
  5. What Does 1 Kilowatt Hour Exactly Mean? Gizmodo. (2010). Available at:
  6. Average heavy goods vehicle fuel consumption: Great Britain, 1999-2014. (2015).
  7. Don Hofstrand. Liquid Fuel Measurements and Conversions. Iowa State Univ. 1–4 (2008).
  8. Where the Energy Goes: Gasoline Vehicles. U.S. Department of Energy (2016). Available at:
  9. Higher calorific values for some common fuels - coke, oil, wood, hydrogen and others. Engineeringtoolbox Available at:
  10. 2014 Fuel Consumption Guide. (2014).
  11. Bottled Water and Energy Fact Sheet. Pacific Institute (2007). Available at:
  12. Santosh, M. Assessment of the Environmental Profile of PLA, PET, and PS Clamshell Containers Using LCA Methodology. (Michigan State University, USA, 2008).
  13. How do plastic bottles damage the environment?
  14. Cost of Living in Madrid. Numbeo (2016). Available at: .
  15. El precio del agua en 53 ciudades. Organización de Consumidores y Usuarios (2016). Available at:

. The total CO2 kg released for every 1 L bottle are, therefore, 0.34 kg. Moreover, for every litre of bottled water, about 3 litres of supplementary water are consumed because of the numerous treatments [11].


On the contrary, every litre of tap water is associated to 0.0003 kg of CO2 [13].


Consequently, even the yearly environmental damage of the two choices is different:


  1. For the bottled water case, 251 kg of CO2 are released in the atmosphere and almost 2200 L of clean water are wasted.
  2. For the tap water sample, the total emitted CO2 is 0.22 kg.


Once again, the ratio between the values is higher than 1000.



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