Contamination of drinking water sources by sewage can occur from raw sewage overflow, septic tanks, leaking sewer lines, land application of sludge and partially treated waste water. Sewage itself is a complex mixture and can contain many types of contaminants.
A working group was constituted by the Ministry of Water Resources under the Chairmanship of Sh S Kumar, Member, Central Ground Water Board (CGWB) to prepare and approach paper on groundwater quality issues and its mitigation plan in Andaman & Nicobar and Lakshadweep Islands.
In this latest report CGWB summarizes various aspects of ground water quality in shallow aquifers in the country with special reference to six parameters viz. salinity, chloride, arsenic, fluoride, iron and nitrate.
The coastal region occupies some of the most potential aquifer systems of the country. The coastal aquifers of India ranges from that of Jurassic to Recent and is seen almost all along the coast right from Gujarat to West Bengal. Some of the aquifers especially the Tertiary to Recent ones are highly potential and are developed extensively.
This paper by CGWB on effective management of available ground water resources calls for an integrated approach, combining both supply side and demand side measures. Says that urgent action is needed to augment the ground water in the water stressed areas.
The groundwater is declining in majority of the areas of Delhi on account of overexploitation of the resources. The rate of decline is as high as 1.7 to 2 meters/year in some areas (South & South west Dist.). Thus seven out of nine districts of Delhi are categorized as overexploited with respect to dynamic groundwater resources.
The methodology for ground water resources estimation is based on relatively sound scientific basis. It also meets adequately well the practical requirements for formulating rational ground water development strategies.