Per capita water usage has been on an upward trend for many years as countries and their citizens become more prosperous their individual water usages increase rapidly annual per capita water withdrawals in the USA for example are about 1,700 cubic meters. Four time the level in China and fifty times the level in Ethiopia in the 21^st century the worlds limited supply of renewable fresh water is having to meet demands of both larger total population and increased per capita consumption the only practicable ways to resolve this problem in the longer term are economic pricing in conjunction with conservation measures. Agriculture consumes about 70% of the world fresh water so improvements in irrigation can make the greatest impact. At present average efficiency in the use of the irrigated water in agriculture may be as low as 50% simple changes could improve the rate substantially though it is unrealistic to expect very high levels of water use efficiency in many developing countries faced as they are with a chronic lack of capital and a largely untrained rural workforce after agriculture industry is the second biggest user of water and in terms of value added per liter used for example production of 1 kg of aluminium might require 1,500 processes have greatly reduced consumption there is still plenty of room for big savings in industrial uses of water.

In rich countries water consumption has gradually been slowed down by price increases and the use of modern technology and recycling. In the USA industrial production and has risen fourfold since 1950 while water consumption has fallen by more than a third Japan and Germany have similarity improved their use of water in processes. Japanese industry for example now recycles more than 75% of process water however industrial water consumption is continuing to increase sharply in developing countries. With domestic and agriculture demands also increasing the capacity of water supply systems is under growing strain.

Many experts believe that the best way to counter this trend is to improve water charges based on the real cost of supplies this would provide a powerful incentive for consumers to introduce water saving processes and recycling few government charge realistic prices for water especially to farmers even in rich California farmers get water for less than a tenth of the cost of supply in many developing countries. There is virtually no charge for irrigation water while energy prices are heavily subsidized too water. Which was one regarded as a free gift from heaven is becoming a commodity which must be bought and sold on the open market just like oil in the oil industry the price increase which hit the market in the 1970s coupled with concerns that supplies were running low led to new sources was a far more costly all over the world it was realized that investing in new sources was a far more costly option than improving efficency of use a similar emphasis on conservation will be the best and cheapest option for bridging the gap between water supply and demand.

On way to cut back on water consumption is simply to prevent leaks. It is estimated that in some of the biggest cities of the world more than half of the water entering the system is lost through leaks in pipes dripping taps and broken installations Even in UK losses were estimated at 25% in the early 1990s because of the failure to maintain the antiquated water supply infrastructure in addition huge quantities of water are consumed because used water from sewage pipes the modern approach however is too see used water as a resource which domestic water soon treated recycled water will account for the most farm irrigation there. There are other examples in cities such as St Petersburg where all municipal water is recycled back to domestic systems.

Another way of conserving water resources better management of the environmental generally the ecosystem can have a severe effect on both local rainfall patterns and water run-off Forest clearings associated with India’s Kabini dam project reduced local rainfall by 25% a phenomenon observed in various other parts of the world where large scale deforestation has taken place Grass and other vegetation acts as a sponge which absorbs rainfall both in the plants and in the ground. Removal of the vegetation means that rainfall runs off the top  of the land accelerating erosion instead of being gradually fed into the soil to renew ground water.

Global warming is bound to affect rainfall patterns though there is considerable about its precise effects. But it is likely that as sea levels rise countries in low lying coastal areas will be hit seawater penetration of ground water. Other countries will experience changes in rainfall which could have a major impact on agriculture yield either for better or for worse in broad terms it is  thought that rainfall zones will shift northwards adding to the water deficit in Africa the Middle East and the Mediterranean a grim prospect indeed.