There is a quotation from the Rime of the Ancient Mariner by Samuel Taylor Coleridge, in reference to the mariner on finding himself marooned on the open sea, "Water, water everywhere, nor any drop to drink", and which summarises the precarious nature of providing a sufficient water supply to a rapidly rising world population which, currently estimated at 6.5 billion, looks set to reach somewhere over 9 billion by 2050. The Earth is the "Blue Planet" because almost 70% of its surface is covered by water, but this is mainly salt-water as fills the seas and oceans, and which without desalination is unfit for drinking, washing in or for most industrial processes. Only 2.5% of the Earth's water is fresh, and about two thirds of that is locked-up in glaciers, mainly in the Antarctic and Greenland ice-sheets, and in permanent snow cover. Nonetheless on inspecting the detailed figures ("Freshwater Resources - The Atlas of Canada") the volume of liquid freshwater available appears vast, at close to 11 million cubic kilometers (km*3). However, near to 10.5 million km*3 of that is located in deep underground aquifers.
The principal sources of water available for human access are lakes, rivers, soil moisture and relatively shallow groundwater basins, from which it is estimated that only about 200,000 km*3 of water is available, which is less than 1% of all freshwater and only about 0.01% of all water on earth. Freshwater has been described as being "more precious than gold" (The Independent, 28th of February), meaning that while we can all live without gold, we certainly can't survive without enough water. Some of the statistics are salutary and some are shocking:
*More than one billion people live without access to clean, disease free water, and 2.4 billion of them (40% of the world's people) have no proper sanitation.
*6,000 children die each and every day from diseases associated with unsafe water, poor sanitation and lack of means for hygiene. This is the equivalent of 20 Jumbo jets crashing every day.
*80% of all diseases in the developing world are caused by unsafe water and poor sanitation.
*In developing countries around 90% of waste water is discharged untreated, which compounds the problem.
*One flush of a toilet in the West uses as much water as the average person uses in an entire day for drinking, cooking, cleaning and washing in the developing world.
*Overpumping deep ground water for drinking and irrigation has caused water levels to decline by tens of meters in many regions, so compelling people to use unsafe quality water instead.
The problem is different from those of other resources, and so there will not be "Peak Water" in analogy with "Peak Oil", since in our use of water we do not change its chemical form, but we do contaminate it and remove it from its reserves. Water is, as we know, renewable, since it is merely moved around by hydrogeological cycles. The pressure on water supply is driven mainly by the rising human population, not only for essential activities such as drinking, cooking, cleaning, hygiene and sanitation, but also as we must grow more food, hence imposing a greater demand on irrigation. In countries such as China and India there is a further demand of industrialisation, as their economies grow. The baseline recommended estimate of a per capita water requirement is 50 litres per day; however, it is possible to get by on about 5 litres for food and drink and another 25 for hygiene. Some countries use less than 10 litres per day (because they have no choice), e.g. Gambia, 4.5; Mali, 8; Somalia, 8.9; Mozambique, 9.3. In contrast, the average Briton gets through around 200 litres and their American counterpart 500 litres per day. It is obvious that rising living standards in the developing world will increase the overall demand for water.
Competition for water will lead to conflict and war, as it must for oil and gas. Potential flashpoint areas have been identified in the Middle East; China, India and Bangladesh; and in Africa, particularly Ethiopia and Egypt, as each side tries to garner more of its share. Climate change seems set to throw its own spanner in the works, through land erosion, sea level rise and flooding, thus causing the loss or contamination of freshwater sources. If global warming is caused (or significantly contributed to) by humans, it is another line in the text that we have to cut back on our use of fossil fuels. Ultimately we will have to, as their current supply becomes exhausted, but by then we may not have sufficient resources of fuel or water to face what lies ahead.