What is wasted water



The topic of water is relevant for two reasons.


If Food is wasted, becomes so that the water too, that was used in their manufacture is wasted.


  • The food we dispose of contains invisible, “virtual” water. For the production of 1 kg of beef are round 15,000 liters of water necessary. If you are aware of this, you will hopefully come to the conclusion that leftover meat should not be disposed of, but can be used for various leftover dishes (such as meat loafs, meat loaf, etc.). Perhaps this realization also leads to some people reducing their meat consumption or giving up meat altogether.


  • Compared to the amount of (virtual) water that we consume due to our food choices (thousands of liters daily), the water savings that we achieve by turning off the water while brushing our teeth are vanishingly small (only a few liters of water).





Making the food system more sustainable does not only mean reducing food waste, but also choosing a diet that is gentle on the resource water and compatible with the decreasing availability of water.





The water that no longer exists



In the last annual reports of the World Economic Forum, the global water crisis is always cited as one of the greatest global risks, both in terms of the likelihood of occurrence and the extent of the effects.


Two of the leading experts for hydrological systems (Mekonnen and Hoekstra) show in a study that four billion people already suffer from water shortages for at least one month a year and 1.8 billion people struggle with drought for at least six months a year. So water scarcity is a widely underestimated problem.


Why does water scarcity occur today (and especially tomorrow) in ever more extensive areas of the world when the water cycle is balanced Water balance (between water supply and water consumption) on the planet?




Image from "Water stories" - © Sanpellegrino 2016



There are two answers to this:








Water footprint



"The water footprint of a product is the amount of fresh water that is used to manufacture the product and is determined along the various stages of the production chain."


The water footprint is an indicator of the water consumption of consumer goods. The concept corresponds to that of the ecological footprint and CO2-Footprint, but instead of land use or the use of fossil fuels, it refers to water.


In the production of agricultural (and other) goods and in calculating their water footprint, three types of water are distinguished.




The colors of the water


The blue water is that in lakes, rivers and underground deposits. It can come from renewable sources that are replenished by rain and snowmelt, or it can come from non-renewable sources. Easily accessible and easily transported, it can be measured, dammed, stored and pumped into water supply networks to meet the needs of different sectors (agriculture, industry and households). Worldwide 70% of this water is used for irrigation (FAO - AQUASTAT), in some countries that are very dry (like the Middle East or North Africa) it is over 90% of the total water consumption.


Green water is rain or snow water that evaporates or "exhaled" through the plants and thus does not turn into blue water. It is used almost exclusively in agriculture, where it covers 84% ​​of the demand.


Grey water is "polluted" water (wastewater) that is used to dilute the pollutants from production processes and is no longer usable for human consumption.




A product's water footprint determines the amount of water required to manufacture a good in a given geographic area. For one and the same food, the water footprint varies considerably from one place to another, depending on the climate, agricultural techniques, crop yield, availability of rainwater or the need for irrigation, etc.


The effects of withdrawing water for the production of a food are again very different, depending on where and how the food is produced. It varies not only the amount of water required, but also the "quality“Of the used Water (blue or green water). It can also be the case that in the event of water scarcity, the available water is withdrawn for priority purposes (especially for domestic use).



Example: orange(the specified quantities in liters refer to an orange of around 200 grams)

Type of water Italy Morocco Spain
green water 56.8 l44.4 l 44.6 l
blue Water 8.2 l 59 l 32 l
grey water 9.8 l litri 7 l 11 l
total quantity 74.8 l 110.4 l 87.6 l



The concept of virtual water is important in order to understand our dependence on hydrological systems, some of which are far away, and the impact our lifestyle, daily activities and decisions have on these systems.


It is important to have an idea of ​​what our water footprint is like and what it depends on.







The world is thirsty because we are hungry



The world is thirsty because we are hungry“Is the slogan with which the FAO expresses the inextricable link between water consumption and food production. The slogan also fits the relationship between the availability of water and eating habits.

In fact, it is we who, through our food choices, influence the abstraction of water in ways that are less and less sustainable. If we want to reduce our water footprint, the most important thing is to critically examine what we eat instead of “just” looking at water consumption in the kitchen, bathroom or garden.


Wasting water never makes sense and it is advisable to conserve water wherever possible. But if we limit ourselves to water consumption for domestic use, we will not be able to positively influence the world's great problems related to water.


© UN Photo / John Isaac, women growing rice in Palung, Nepal



So what to do





Also take a look at our UBO app: There you will find the water footprint for over 500 foods, recipes for recycling leftovers, tips for optimal food storage and you can even create a shopping list!