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Last edited 07 May 2019
Water is a chemical compound that is essential for all known forms of life. It is a transparent, tasteless, odourless and almost colourless substance that covers 71% of the Earth’s surface and is the main constituent of rivers, lakes, oceans and so on.
Water resources are natural sources of water that have the potential to be useful to humans. This might be for drinking, sanitation, cooking, washing, agriculture, commercial purposes, industrial processes, landscape maintenance, recreation and so on.
Most of the water on Earth is salt water. Less than 3% is fresh water, and more than two thirds of this is frozen. The majority of the unfrozen fresh water can be found as groundwater, with just a small proportion above the ground as surface water (such as watercourses, wetlands and so on), or in the air.
Access to safe water is essential for good health. The 2030 Agenda for Sustainable Development recognised access to safe drinking water and sanitation as a human right. However, in the foreword to the 2019 World Water Development Report, Audrey Azoulay, Director-General of UNESCO conceded that: “… nearly a third of the global population do not use safely managed drinking water services and only two fifths have access to safely managed sanitation services.”
In theory, there is enough freshwater on Earth to fulfil the needs of the global population, and the ongoing watercycle (evaporation, cloud formation and rain) means the supply is continually replenished. However, a combination of factors can result in local scarcity:
- Demand distribution does not match resource distribution. Population densities are becoming more localised, consumption patterns are changing, and new demands are emerging. This stresses water resources at a local and regional level.
- Even in areas where there is sufficient water, some people may not be able to access it due to asymmetric power relations, poverty other inequalities.
- Climate change is accelerating global water circulation, amplifying climate variability and giving rise to temporal water scarcity.
In addition, energy and infrastructure are required to treat water to make it fit for consumption and to transport it to sources of demand. Desalination in particular, in which saline water such as sea water is treated so that it can be used, is a very resource intensive process.
In England, two thirds of water is abstracted from reservoirs, supplied by rivers and streams and stored until required. The remainder is largely from ground water sources. This can cause problems during times of draught, when there is insufficient supply and stored water depletes. In these circustances water companies may be permitted to impose a ban or restriction on the use of hosepipes and sprinklers or can apply to the government for a drought order limiting the use of water for specific activities, and / or making alternative arrangements for the supply of water, for example by erecting stand pipes.
Water supply problems in the UK may become more common as a result of climate change, with precipitation patterns becoming more extreme, but less frequent. This problem is exacerbated by high leakage rates from an ageing water distribution network.
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