Water is the basic need of a living organism. No one can live without water. The demand for freshwater is likely to exceed its supply by the first or second decade of the next century. An acute crisis is expected to follow in some regions of the world. The shortage of water shall make many localities barren, devoid of life. Fertile land will become deserts.

Conservation of fresh water is, therefore, an absolute necessity of today. Otherwise the tomorrow will be grim, drier and barren to live through. It is somewhat consoling that though the actual quantity of water drawn has already reached the level of total water availability, the irrecoverable consumption of water is well below this level. Needless to say this is due to a number of steps undertaken to minimize wastage of fresh water resources and to make more efficient use of the available water. Some of these may be summarized as follows:

1. Water Economy, Re-Use and Recycling:

For almost all spheres of human activity till date, more water is drawn than the amount actually needed. Much of the surplus water is returned to surface flow in an impure state. A little care can reduce the over-consumption. We waste water because of its easy availability.

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If a water meter is installed and money charged for every bucket of water we use, water consumption in domestic establishments, livestock management and industries shall drastically decline. The resultant surplus may be diverted to regions of water scarcity. This shall also reduce production of waste waters which pollute our aquatic systems.

Power generation is another sphere of human activity wherein a large amount of water is needed. Most of it, however, is used as coolant (about 90-95%). Irrecoverable consumption is only 5-10%. The heated waters from thermal power plants may be utilized elsewhere after proper cooling.

The same is true for many industries. Water used once may be used again for another purpose. All processes do not require good-quality water. Agricultural runoffs from fields can likewise be used to irrigate cropland down the stream while an efficient use of water with conditions of proper drainage can significantly reduce the agricultural runoffs.

2. Development of an Efficient Distribution System:

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Water resources are not distributed evenly. Some localities have plenty of water. Others have little of it. Therefore, transport of water from one place to another becomes an essential part of water conservation efforts. Many river basins have plenty of water which flows down unused to the sea. This surplus can be diverted to drier regions through a system of canals and pipes. Water drawn out from underground sources can also be transported to zones where underground water cannot be tapped. The surplus of one basin can be used to make up the deficit at another.

3. Reduction of Pollution and Recycling of Water:

Pollution spoils huge quantities of our surface water. All possible efforts should be undertaken to divert waste waters to some treatment plant instead of releasing them into our surface waters. While treated water can be safely discharged in our aquatic systems, it may also be recycled where there is more pressing need. Ordirtarily the bio­degradable impurities of waste waters make them most undesirable.

These can be conveniently decomposed by some biological treatment followed by treatment with a suitable disinfectant. This makes the water concerned almost as good as it was earlier. If not for direct consumption these waters can be used satisfactorily for other purposes such as washing and cleaning, as coolant in industries, for irrigation etc.

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4. Enhancement of Surface Storage Capacity:

About 27,000 cubic kms of fresh water which rush down to the oceans through streams and rivers of the world as flood flow are of no use to the mankind. We can store this water in tanks and reservoirs for use during drier seasons. This can be done by erecting embankments and dams which check the flood-flows and detain water for longer duration on land surface.

Through a system of pipes and canals the water can be supplied wherever needed. The potential energy, the energy of water flow as it moves from a higher place to lower may be used in hydroelectric power generation, while the reservoirs which develop behind the dam may be used for fisheries and other recreational activities.

However, surface storage of water, in huge quantities, is a risky and costly venture. Water losses through evaporation and seepage are enormous both from the reservoir and the distribution system. Much of the water infiltrates the soil and moves to the ground water table. Large areas of fertile land are submerged which may include human settlements as well.

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Natural ecosystems are destroyed. The pressure of standing water table enhances seismic activity which may precipitate an earthquake. A crack in the dam, sabotage or bombardment during wars is catastrophic to the people living down streams. Entire localities may be washed away by rapidly gushing waters. The multimillion rupees projects are gradually made defunct by silt and debris carried by the river water if little is done to reduce soil erosion upstreams in the catchment area of the river.

5. Improvement of Underground Storage Capacity:

An enormous amount of fresh water is stored in underground deposits. It represents accumulations over a long period of time. Every year, about 10-15% of total precipitation enters the ground water table. These deposits regularly feed streams and rivers during drier periods. Ground water deposits are cheap and easily obtainable source of freshwater except for the cost involved in its withdrawal.

We can improve the ground water storage capacity of earth’s crust by providing an effective plant cover over the soil surface. Plants obtain most of their water from soil moisture and keep the surroundings cool and humid, thereby, preventing excessive loss of water through evaporation. They check the flow of water and impede air currents.

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As a result of which more water percolates down the soil surface to add to the ground deposits. On bare and denuded surface, much of water, deposited by precipitation, flows down quickly as flood flows. Little of it permeates the soil surface to recharge the ground water table. In dry seasons there is an equally rapid loss of water from the soil in absence of plant cover.

6. Augmentation of Existing Supplies of Fresh Water:

As mentioned earlier, annual precipitation has been considered to be the upper limit up to which we can draw water from its deposits on land surface or beneath. An overdraft is detrimental to the ecology and environment of the locality. Many regions of the world with scanty rainfall have no other choice but to augment their water supplies by other means. This can be done by:

(a) Desalination of sea water:

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A huge store of water exists in our oceans. Only if the salt content of sea water is removed we can use the water for consumptive purposes. This can be done by desalinization plants, which are essentially huge distillation sets operated on solar energy. Desalinization plants are already under operation in a number of Middle East countries. However, these plants are very expensive.

(b) Artificial rain making:

In general only 20-30% of the moisture content of atmosphere over a locality precipitates as snow or rains. It has been observed that clouds with tem­peratures ranging between 5° – 20°C nearly always lack condensation nuclei over which moisture condenses to form droplets of water. Small particles of substances like Silver iodide, Sodium chloride, dry ice (solid CO2) etc. are injected into a thick layer of clouds (cumulus clouds), around which moisture condenses and droplets of water form which sink down as rains. In a number of countries active experiments are being carried out in this direction. However, the process of artificial rain making is still in an experimental stage.