Sewage threat to water sources

Last Updated 28 August 2013, 17:28 IST

Sewage has to be made to pass through only underground pipes in the interiors of towns and cities.

Sewage contamination of water bodies in urban and rural areas, of rivers and bore well water has been increasing. And this has emerged as a serious difficulty in reaching potable water to people everywhere. Underground drainage network generally culminates in urban lakes and rivers causing this contamination.

This water reaches the bottoms of bore wells as leachate and the yield becomes toxic and unusable for drinking and other domestic purposes. In fact, milk contamination in many parts of the country also is due to this water contamination as water is the general milk adulterant; milk is observed to have urea, sewage elements, detergent etc., in certain proportions, all owing to this contaminated water. Therefore management of lakes in urban and rural areas has to be urgently improved and technically upgraded to solve this widespread potable water problem.

An integrated and not piecemeal approach to this potable water problem has to be designed. And for this we should proceed to connect tanks among themselves topographically and ultimately with nearby rivers as a part of well designed plan for systemic reconstruction of lakes. Each tank has to be restored by repairing and bolstering  its bund and sluices and its overflow outlets.

Methodical desilting is a part of this restoration; this silt may be used as manure and also as bund material. These respective tank outlets have to be connected to the corresponding lower level tank. Also the catchment areas of these have to be restored so that the repaired and upgraded storm water drains carry flows ultimately to replenish the tanks as much as possible in the rainy season and reduce eutrophication (phenomenon of  inordinate increase in aquatic nutrition and drastic reduction in oxygen content destroying the life of aquatic fauna).

Detoxification plants

These storm water drains, particularly the larger ones, have often become conduits to sewage flows. Therefore, freeing lakes from sewage needs many other measures. Sewage has to be made to pass through only underground pipes in the interiors of towns and cities and only at the far away outskirts, they should be released to open drains or sewage canals.

These canals again have to be hierarchically connected and they should on both their sides be provided with well maintained suitable flora with potential to detoxify water; and these sewage canals have to be provided with dry mud and stone masonry lining facilitating water absorption by the earth and other biological processes. These huger canals may get to sustain aquatic creatures and attract birds and these fauna also may contribute to detoxification and may as well be a source of valuable and often specialised kinds of manure — all these are matters to be thought about, decided and administered by biologists and environmentalists.

In this sewage canal system, modern day detoxification plants also may be introduced and use of recycled water also brought into vogue. Here well designed canals and their administration may yield a lot of valuable silt also; this facilitates upgradation of soil fertility, agriculture and may be employment intensive.

These sewage canals have to be kept unconnected from lake connectivity flow channels. The sewage and storm water flows must not become mixed. And these parallel flow channels, culverts and vents, their design and maintenance, along with lake connectivity complements are indeed tasks before engineers and environmentalists. This will involve large scale time consuming investments and comprehensive planning; all employment and skill intensive. To be accomplished over a period of decades as parts of plans and sub plans, all components of five year plans.

With the advent of large irrigation dams, maintenance of lakes has suffered neglect; only now, during recent decades, there is a gradual realisation about the harm this neglect has caused. In particular, environmentalists have grown sceptical about large dams; they have expressed concern regarding the disablement by dams of anadromous and catadromous movements of fish shoals, migration away from and towards sea waters, all breeding habits. All these have a telling impact on the availability and variety of fish, substantially affecting the food economy.

 With decentralised rain water conservation through tank maintenance getting neglected, cities and towns are getting water logged inundating tenements in monsoons and drought stricken during summers. The idea of supplying water to tanks from large scale irrigation canals may not be a good idea. The problems of land acquisition for canals, using up lake interiors by private vested interests, loss of village commons, grazing lands, burial grounds etc., are all seen; machinations of vested interests.

(Published 28 August 2013, 17:28 IST)

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