Today in almost all spheres of human activity more water is drawn than what is actually needed. Due to carelessness much of it is wasted and allowed to flow out in an impure state. At many places enough clean water is no longer available.
The rapid rise in demand for fresh water is naturally a result of an equally rapid growth in the number of consumers. But there are a number of other causes as well which have contributed significantly to the wastage and degeneration of our fresh waters. These can be summed up as follows:
1. Reckless Over-Consumption and Misuse:
Water is often misused recklessly. As it is a means to achieve an end little importance is attached to it. Taps are kept running while people do other things. Everywhere we tend to use more water than is actually necessary, often because it is available in plenty or because we can afford the wastage. Such an attitude causes overconsumption and wastage. A little care can result in substantial savings and longer life for our resource base or else the water thus service can be diverted to regions where there is a shortage.
2. Pollution of Natural Waters:
From ancient times surface waters have provided fresh water to the mankind. These aquatic systems have also been used as a convenient means of disposal of wastes and waste waters. Both running and stagnant waters are capable of degrading the discarded materials into simple and harmless constituents. However, in stagnant waters the products of decay and decomposition persist in the system whereas in running waters they are carried away with water currents.
With a sudden rise in human population the volume of wastes and waste waters has risen considerably. These wastes also include a number of non-biodegradable substances and substances resistant to degradation. Natural waters are no longer capable of decomposing these impurities. Most of our water bodies, streams and rivers have become polluted and unfit for human use. In 1970 A.D. about 3,500 cubic kms of water were diverted for human use while about 5,800 cubic kms of clean water were found to be polluted with varying degree of pollution (Rogers, 1991).
3. Eutrophication of Natural Waters:
Eutrophication is a natural phenomenon which involves gradual enrichment of nutrients and development of plant and animal life in a lifeless water body. Natural eutrophication is, however, a very slow process. This process is accelerated by addition of wastes and waste waters which contain plenty of nitrates, phosphates and organic matter.
While phosphates and nitrates are essential plant nutrients, decay and decomposition of organic matter yield plenty of plant nutrients. Addition of wastes and sewage causes the water body to become exceedingly rich in plant nutrients. Blooms of algae and other organisms appear and make the water useless. The entire biomass may suddenly die and start decomposing causing a lot of other problems. Organically rich waters also support a population of many pathogenic organisms and vectors which transfer diseases from one individual to another.
4. Pollution of Underground Water Table:
Underground water deposits receive their waters from surface waters which percolate down the upper strata of soil and rocks. Though soils possess efficient biological machinery which effectively degrades impurities present in the water, a number of materials resistant to degradation as well as non-degradable matter may pass through the upper layers of the soil and pollute the underground waters. Salts of chromium, cadmium, mercury, lead etc. may be present in underground waters in concentrations sufficient to cause harmful effects on a living system.
5. Depletion of Underground Water Table:
Pressure of demand on underground water resources has gone up considerably. Every year more and more water is drawn up from sub-surface layers whereas recharging of underground water has been slowed down. Massive deforestation has caused disappearance of plant cover over a large area of land surface. In absence of plant cover most of the rain water flows out and down quickly in streams and rivers.
Little of it percolates down to sub-surface layers to recharge the ground water stock. With rapidly flowing waters we are also losing a considerable amount of top-soil. In a number of localities where underground water is regularly drawn the water table is receding deeper and deeper because output exceeds the input.