There is a persistent increase in the demand for water because of the growth in population and the rise in the standard of living, and the growth in commodity production and in service industries. Water supplies everywhere are also under threat from climate change. There is great pressure on the water resources of many countries, particularly those developing countries located in arid or semi-arid regions. Acute water shortage exists in many areas of the world and is likely to become more severe in future years. In some areas, further economic growth will not be possible until adequate additional water supplies become available. In other areas, failure to increase the water supply may well result in standards of living being reduced below present levels. Competition for water resources will heighten, arousing conflict. Countries with abundant water resources, like Canada and Norway, will be subject to increasing demands to share or sell their resources.
Demand for water is growing several times faster than population, as agriculture, industrial and domestic uses increase. Global water use doubled between 1940 and 1980, and is due to double again by the year 2000. In 1998 it was reported that about half this increase is caused by population growth.
World population is rising at present at an average rate of about 2% per annum, which means that, other factors being equal, world water demand will double about every thirty-five years. This demand, however, is further raised by the rise in the standard of living, leading to greater requirements for water for human consumption. This is brought about by the movement of population from primitive to modern housing, with water supply and bathrooms; by the rapid urbanization evident in all countries; and by numerous other factors.
Practically every increase in the production of goods – from rice to electricity and chemicals – requires increased quantities of water. The same applies to service industries, from commercial laundries to hotels. The increased demand for water resulting from the growth in the production of goods and the expansion in service industries is difficult to estimate because much will depend on the type of commodities to be produced and the type of service industries to be established. It should be noted, however, that the increased demand for water for the production of goods and services is independent of the increased demand for water for the population and is therefore additional to the latter.
Global use of energy has tripled during the past three decades. This places proportionate demands on water use. In some places the availability of water is becoming more of a constraint on hydroelectric energy production than the availability of primary fuel. A single coal gasification plant producing 7 million cubic meters of burnable gas per day would require as much as 25 million cubic meters of water a year. Obtaining and transporting the necessary water would be more damaging to the environment than strip-mining the coal itself.
Global consumption of water is doubling every 20 years, more than twice the rate of human population growth. According to the United Nations, more than one billion people on earth lacked access to fresh water in 1999. By 2025, the demand for fresh water is expected to be 56 percent more than available; and that 1.8 billion people will live with dire water shortages and two-thirds of the world’s population could be living under stressed water conditions.
In other words, in a very short while most of the world's people will face shortages or absolute scarcity. This is not a simply a matter of seeing more stories of wretched African children dying in horrible droughts, but of imminent water crises in America (the Southwest, Florida, and California especially), Southern Europe, India, England, China, and other nations not usually thought of as facing massive water shortages.
In 1990, a total of 28 countries with a population of 335 million people combined faced water shortage pressure or water scarcity. By 2025, between 46 and 52 countries will fall in this category. It is estimated that the overall population of those countries will increase to between 2.781 and 3.29 billion people in the next three decades depending on their population growth rates. The difference between these two figures is equal to 1.5 times the people which lived in 1990 under such circumstances.
A fifth of the world's population already lacks reliable access to clean water and, with birth rates climbing in many regions, the problem is becoming acute. In 1998 it was predicted that if present water resource planning was not changed, almost two thirds of humanity might suffer from moderate to serious water shortage before the year 2005.
According to one estimate, by the year 2000 one half of all the earth's annually renewed water – precipitated onto land – will be used by man. Unfortunately, because the actual availability of water bears little relationship to the distribution of population and demand, local shortages will become increasingly frequent as population and related consumption increase. Some 80 countries, with 40% of the world's population, already suffer serious water shortage. In the face of population growth, many developing countries are unable to reduce the numbers who are lacking adequate water supplies. This will cause special problems for some rapidly growing cities.
In addition to problems of supply, the reliability of water flow is being disrupted in many areas as watersheds are deforested. More than half the population of developing countries, excluding China, lacks convenient access to safe water supplies. The resulting poor sanitation, in combination with undernutrition, accounts for the daily deaths of 40,000 infants and small children. Up to 10 million people died each year because of water-borne diseases such as typhoid and dengue fever.
China's per capita water availability is one-third of the world's average and will drop as the population continues to increase. Industrial use of water almost doubled in the period between 1980 and 1993; in 1999 industry consumes 17 percent of China's total water supply. In 75 percent of China's cities, the demand for water exceeds the supply. Groundwater levels in the North China plain have been dropping by 1 to 2 metres per year. It is expected that China's demand for water will increase by 21 percent from 2000–2010.
Northern Africa and the Middle East would be particularly affected by severe constraints on water availability. The Arab oil rich countries such as Kuwait, Qatar, Bahrain, Saudi Arabia and the United Arab Emirates are five out of nine countries in the world which have the least per capita water resources. In Saudi Arabia, 90 percent of water resources being used for irrigation of agricultural lands come from the non-renewable underground water resources. If the resources continue to be exploited at the current rate of nearly 10 percent, they will totally run out in the next 10 to 20 years. To this end, the life span of Saudi Arabia's underground water resources has been estimated by the year 2007.
By the year 2100, Africa is projected to have a population five times that of today; the population of Asia is expected to double. During the next century, the amount of water available on a per capita basis will be reduced in Asia from the 1980 figure of 5100 cubic meters, to 2600; and in Africa from 9000 cubic meters per person, to 1600. These continental averages conceal striking regional differences. Even if sophisticated computer-based conservation and management and heavy irrigation schemes were introduced, water availability would not allow for more than a 50% increase in population in North Africa and the Middle East.
In many countries, such as Israel, supplies from groundwater are decreasing because of rapid withdrawals. In other countries, such as Bangladesh, most wells are polluted because of lack of sanitation; and in yet other countries, such as Egypt and Libya, overpumping from the ancient aquifers has allowed sea water from the Mediterranean to seep into the wells. This is also a problem in certain parts of Australia where, because of the increasing amounts of groundwater being withdrawn for irrigation, the water table is dropping and seawater is entering the aquifers, affecting water supplies for farms.