Freshwater makes up a very small fraction of all water on the planet. While nearly 70 percent of the world is covered by water, only 2.5 percent of it is fresh. The rest is saline and ocean-based. Even then, just 1 percent of our freshwater is easily accessible, with much of it trapped in glaciers and snowfields. In essence, only 0.007 percent of the planet's water is available to fuel and feed its 6.8 billion people.

Water plays a central role in all aspects of human development .Water demand and availability have become more uncertain, and all societies are becoming more vulnerable to a wide range of risks associated with inadequate water supply, including hunger , thirst, high rates of diseases, death, lost productivity , economic crises and degraded ecosystems. These impacts elevate water to a crisis of global concern.

According to the United Nations, water use has grown at more than twice the rate of population increase in the last century. By 2025, an estimated 1.8 billion people will live in areas plagued by water scarcity, with two-thirds of the world's population will live in water-stressed regions as a result of use, growth, and climate change.

According to United Nations Children's Fund (UNICEF) that almost 90% of children deaths from diarrhoeal diseases are directly linked to contaminated water, lack of sanitation, or inadequate hygiene.

Human behaviour has altered the planet's climate and chemistry, its snow cover, permafrost, sea and glacial ice extent, and ocean volume. Water needs to be considered not in isolation but as part of a water-energy-food health nexus, in which each sector affects, and is affected by, the others.