GROUND WATER QUALITY & POLLUTION STATUS
Report - Ministry of Water Resources
Ground Water quality monitoring is being carried out through analysis of ground water samples collected mostly from the
dug wells tapping the phreatic aquifers. The samples are collected during pre-monsoon period from nearly 15000 wells distributed through out the country. In addition, ground water samples are also
collected during the ground water management studies, ground water exploration and special studies. The
samples are analyzed for the major cations and anions for evaluating the ground water quality and its suitability for various uses. The data of the ground water quality are being computerized in the dedicated software. The quality data along
with the analysis are represented the form of graphs ,maps, tables and are being produced in Ground Water Year books repared by all the regional offices.
In general ground water quality in shallow aquifers is suitable for use for different purposes, except few areas in which high concentration of some of the constituents are reported. The quality in deeper aquifers varies from place to
place and exploration work is going on to assess the suitability of water for various uses. High
incidence of the constituents such as Arsenic, Fluoride, and Iron has been reported from some of the areas which has been mostly
attributed to geogenic reasons. Similarly salinity both in the inland and coastal areas has been reported from various parts of the country.
Nitrate and Heavy metals are the important constituents, high concentration of which poses severe health problems may be attributed to anthropogenic activities
The brief description of the ground water quality related problems in India are as below:-
GROUND WATER SALINITY
The ground water salinity is of two types.
i) Coastal salinity due to sea water ingress in coastal area.
ii) Inland salinity due to processes other than the sea water ingress.
The coastal tracts in India cover parts of Gujarat,
Maharashtra, Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Orissa & West Bengal. Besides the Inherent ground water salinity in the coastal tract Sea water intrusion is also reported. In certain areas problem of
upcoming of saline water has also been reported due to overexploitation of ground
water. The coastal salinity problems have been observed in a number of places in coastal areas of the country. Problem of salinity ingress has been noticed in Minjur area of Tamil Nadu and Mangrol Ė
Chorwad- Porbander belt along the Saurashtra
coast. In Orissa, in an 8-10 km. wide belt of Subarnrekha, Salandi, Brahamani out fall regions in the proximity of the coast, the upper aquifers contain saline horizons decreasing
landwards. In Pondicherry region east of Neyveli Lignite Mines salinity ingress has also been observed.
The Inland Ground water salinity in India occurs mainly in the states of Maharashtra, Punjab, Rajasthan, Haryana, Gujarat, Karnataka, Uttar
Pradesh, Delhi, Orissa and Bihar. The occurrence of inland salinity may be due to over development
of ground water, use of surface water and ground water in complete isolation,
characteristics of aquifer or some other reasons. About 1.93 lakh sq.km area has been estimated to be affected by saline water of Electrical Conductivity >4000 m S/cm. There are several places in parts of Rajasthan and
southern Haryana where EC values of ground water are greater than 10000 m S/cm making water non-potable. In some areas of Rajasthan and Gujarat ground water salinity is so high that the well water is directly used for salt manufacturing by solar evaporation.
High concentration of Fluoride in ground water beyond the permissible limit of 1.5 mg/L is a major health problem in India. Nearly 90% of rural population of the country use
ground water for drinking and domestic purposes. With 199 districts in 19 states of India identified with problem of excess of Fluoride in ground water. There is lot of variation in the degree of occurrence of
fluoride such as only one district is affected in Jammu& Kashmir where as all the districts of Rajasthan are affected with high
fluoride in ground water. A huge rural population is threatened with serious health hazards of Fluorosis.
The occurrence of Arsenic in ground water was first reported
in 1980 in West Bengal in India. In West Bengal 79 blocks in 8 districts have been found to contain Arsenic sporadically
beyond the permissible limit of 0.01 mg/L as per Bureau of Indian Standards. About 16 million people are at risk zone.
The most affected districts are on the eastern side of Bhagirathi River in the districts of
Malda, Murshidabad, Nadia, North 24 Parganas and South 24 Parganas and western side of the river districts of Howrah, Hugli and Bardhman.
In all the cases high arsenic is also associated with high iron. The occurrence of Arsenic in ground water is mainly in the
intermediate aquifer between 20-100m. The deeper aquifers are free from Arsenic contamination but the
tube well to be designed with proper cement sealing to prevent percolation from above arseniferous
aquifer. Apart from West Bengal Arsenic contamination in ground water has been found in the State of Bihar, Chhattisgarh and Uttar
Pradesh. In case of Bihar 12 districts have been reported with contamination of
ground water. It has also been reported in Dhamaji District of Assam. The occurrence of Arsenic in the states of Bihar, West Bengal and Uttar Pradesh is in Alluvium formation but in the state of
Chhattisgarh, high arsenic is associated with volcanic formation.
Iron in an essential element in both plant and animal metabolism. The concentration of iron in natural water is
controlled by both physico chemical and microbiological factors. An additional factor involved in the mobility of iron in ground water is the presence of bacteria.
High concentration of Iron in ground water has been observed in more than 1.1 lakh habitations in the country. The highly contaminated ground water by iron is in Assam, West Bengal,
Orissa, Chhattisgarh, and Karnataka. Localized pockets are observed in state of NE, Bihar, UP, Punjab,
Rajasthan, Maharashtra, Madhya Pradesh, Jharkhand, Tamil Nadu and Kerala.
NITRATE & HEAVY METALS
The most common contaminant identified in ground water is dissolved nitrogen in the form of Nitrate
(NO3). Decomposition of organic matter present in soils leaching, of soluble fertilizers, human and animal
excreta are the source of nitrate in subsurface waters. The disposal of urban waste and
land fills are one of the major causes of nitrate pollution in ground water. Nitrate is a common constituent present in the ground water especially in shallow aquifers. The source is
mainly from man made activities. In India highest concentration of nitrate has been found in
Bikaner, Rajasthan, however the urban as well as rural areas of several states are affected by high concentration of Nitrate. Nitrate pollution of ground water is not only in rural areas but even in urban
areas widespread pollution has been reported.
Haphazard disposal of industrial effluents has been one of the major reasons of ground water pollution due to heavy metals. Once the aquifer gets affected it is very difficult to clean
the same. The ground water pollution of heavy metals such as chromium, lead, Nickel etc in ground water has been reported from various parts of the country mainly due to unplanned disposal of industrial effluents.
Ground Water Pollution report on November 30, 2011
As reported by the Central Ground Water Board (CGWB), ground water
samples are collected through a network of around 15000 observation wells once a year during pre-monsoon season. The ground water samples
are also collected for water quality analyses during the course of ground water exploration, ground water management studies and special
studies in the selected urban / industrial areas. The samples are analysed for major ions. The State-wise details of groundwater
contamination with fluoride, nitrate, arsenic, iron and heavy metals in
excess of Bureau of Indian Standardís prescribed limits in ground water
are given at Annexure.
The following steps have been undertaken to ensure clean and potable water:
* In areas affected by the problem of geogenic contaminants like
arsenic and fluoride in ground water, the Central Ground Water Board
carries out exploratory drilling in consultation with the State agencies
for delineation of contaminant free aquifer zones. Exploratory wells
after completion and collecting necessary scientific information are
handed over to the concerned State agencies for utilization by them.
* The potability of water is being ensured by the Public Water Supply, Public Health Engineering Department, Jal Board, Jal Nigam and other Municipal Authorities. The Ministry of Drinking Water and Sanitation is supplementing the efforts of the States under its National Rural Drinking Water Programme in providing safe drinking water in rural areas of the country.
* Action Plans have been evolved as per Comprehensive Environmental Pollution Index
for Critically Polluted Areas.
* Establishment of Common Effluent Treatment Plants for cluster of Small Scale Industrial units.
* Urban centers have been identified for interception, diversion and development of treatment facilities under various River Action Plans.
This information was given by the Minister of State for Environment and
Forests (independent charge) Shrimati Jayanthi Natarajan in a written
reply to a question by . ShriNishikant Dubey in Lok Sabha on
November 30, 2011