One of the most basic necessities for every form of live on our planet is water, without it most life will eventually die out. Water, is even more important than food. A human can survive for weeks between meals but only days between drinks. Per day we need around 2 to 3 litres of fresh drinking water, according to environmental factors. In a hot climate more water is required, due to a higher transpiration rate. At present around one billion people or more lack proper drinking water. In western worlds drinking water is not only used for consumption, but also for cleaning, washing, showering and flushing the toilet, when this is added to water consumed, the amount can ad up to 300 litres or more per person per day.
Only a tiny amount of the total volume of water on Earth is actually fresh water and even a smaller amount of this fresh water is available for life.
The source of fresh water is called the water cycle, and the main driver or pump in this cycle is the sun. Evaporation of water from the large surfaces of the oceans form clouds, which are driven inland by winds, where they cool down and shed their contend of water on the land in the shape of rain snow or hail. Evaporation of water cleans our most if not all of the salt present in the sea. On land the fresh water is stored in the shape of snow, in aquifers or groundwater and in the soil. The access water or melt water is slowly brought back to the sea through rivers and lakes. This water cycle is vital for every type of life on land.
