“Virtual water” refers to water that is used in other countries (see Appendix 1) to produce the agricultural and industrial products consumed in Switzerland (60% and 40% of the virtual water share, respectively). If the water consumed virtually by each person is added to the Swiss water consumed by each person, the total amounts to over 4,000 liters per person per day. If all the products that we consume were produced in Switzerland, we would use about a third of our renewable water resources ( the water now flowing in streams and rivers).
In Switzerland, the production of milk, beef and pork products accounts for three quarters of all agricultural water consumption. In contrast to animal products, most plant products are imported. This is reflected in the virtual water shares: most virtual water is in cocoa, followed by coffee, sugar, nuts, wheat, oilseeds and rice. Many of these plants would not survive in the Swiss climate, as many of them are grown in tropical areas where it rains a lot. The problem arises when the same products are grown in drier regions where they need to be heavily watered. Thus, water scarcity in some regions is exacerbated by the production of export products. Examples include the production of cotton (1 kilogram of cotton requires 10,000 liters of water) and rice (2,500 liters for one kilogram) in China, Spain or Portugal.
Switzerland also exports products (about half of the total production of agriculture and industry is exported) whose production requires a lot of water. The balance of virtual water (imported virtual water minus exported virtual water) is positive and corresponds to the volume of Lake Thun. In other words, an amount of water equivalent to the volume of Lake Thun is used to produce foreign goods that are consumed in Switzerland.