All living organisms are largely water and cannot survive without a regular supply, it is therefore essential that water supplies are assured in a sustainable development.
The supply of water for human consumption and for plant life is dependent on the cycle of water through evaporation and condensation, mostly as rain, but also as melting snow from glaciers in some parts of the world. In desert regions the water supply is from underground aquifers in oases or from seasonal river flow as the Nile.
Drought occurs when demand exceeds supply, so that even in a place that has significant rainfall, drought can occur if adequate storage is not provided for long dry spells.
For sustainable developments in areas where rainwater supply is intermittent either adequate storage must be provided, or some means for recycling water and management must be created. The supply of water to urban areas depends on water from reservoirs or aquifers, which may be quite distant from point of use and dependent on pumping. Such supplies depend on the reservoirs being large enough to store enough water in wet seasons to meet the volume of demand in dry seasons.
The technologies for water management and recycling are available for any degree of likely drought conditions, even where there is no rainfall, as in spacecraft.
WATER HAS ANOTHER ROLE TO PLAY IN SUSTAINABLE DEVELOPMENT
Water molecules are two hydrogen atoms and one oxygen atom bonded together, and it is feasible to split the molecule to provide HHO gas (Browns gas, name after the initial discoverer of the process) for burning in place of fossil fuels in internal combustion engines, or providing heat as in welding torches.
Another technology uses new metal catalyst to split hydrogen from water
There is an unsolved mystery about water fuel cells invented by Stanley Meyers in the1980s, claimed to produce HHO at a rate sufficient for immediate combustion without need for storage. Meyers did not manage to market his invention before he died in 1998, but his technology has been replicated many times and may one day prove to be the power behind sustainable heating, power and transport.