The importance of water resources cannot be overemphasized as they are the foundation of life and livelihoods on Earth. They have been an ‘invisible engine’ of the human development throughout millenniums. In other words, water has been the center of economic and social development not only maintaining health, but also being used in agriculture, transportation, and industry. Thus, unsustainable supply of water is likely to lead to a humanitarian and economic catastrophe. For this reason, the access to water, historically, has been one of the main causes of tensions between countries and nations. People were aware of the fact that if society allows freshwater to be wasted and polluted, the countries will not survive (Gleick, 1993). Nevertheless, growing population and the expansion of highly- material, energy, waste and pollution production systems have increased pressure on the global water sources (Dell`Angelo et al, 2018). Notwithstanding the fact that about 71% of the Earth`s surface is water-covered, only about 2.5% of all water sources are fresh water, and of this, only 0.4% is surface water, and about 30% is ground water. Most of the rest is in glaciers and icecaps, which are mostly inaccessible (UNEP, 2007). Therefore, as water sources become more polluted and wasted, the demand for fresh water growths. Nowadays 4.3 billion people (approximately 71% of the global population) live under conditions of occasional or permanent water scarcity. By 2030, the industrial and population demand for fresh water in both developed and developing countries is expected to exceed the currently available and accessible fresh water supply by 40% (Mekonnen & Hoekstra, 2016). According to the World Economic Forum report (2015), water crises was listed as the largest global risk in terms of potential impact. Thus, these developments marked the beginning of a new era in the humankind history: the development under water scarcity.
However, these problems had not been the integral part of the world development agenda before 2015. For instance, they were not included to the Millennium Development Goals (MDGs) (UN, 2015). The situation changed in 2015 when ration water usage was chosen as a foundation for achievement of two out of seventeen Sustainable Development Goals (SDGs), namely 6th ‘Clean, accessible water for everyone’ and 14th ‘Clean oceans and seas’ (UN, 2018).