Dugwells: a solution to the
A revival of traditional water harvesting systems involving local
communities could be just the solution to the arsenic menace in West Bengal. Through the
efforts of R N Athavale, scientist emeritus at the National Geophysical Research
Institute, Hyderabad, and the Centre for Science and Environment as the central
secretariat (CS) of the National Water Harvesters Network (NWHN), attempts to
provide arsenic - free water to affected communities in West Bengal have been initiated.
Efforts to provide sanitary dugwells in two identified arsenic affected villages
Kamdev Kati and Ambika Nagar in district North 24 Parganas of West Bengal have started. If
successful, this low cost option could be widely replicated in the region through
non-government organisations or by the communities themselves.
The rationale behind this project is simple. Arsenic content beyond permissible levels
is usually found in water from deep tubewells, at a depth of about 30m. On the other hand
it is rarely found in phreatic or unconfined aquifers.
It is this very property of phreatic aquifers that will be exploited. These shallow
aquifers will be tapped by dugwells to provide arsenic free water, which can subsequently
be recharged by harvesting rain.
According to Athavale, dearsenification of pumped water i.e. removal of arsenic is not
the only solution to the arsenic problem. "All available options must be explored and
an appropriate technology then introduced," he feels.
In line with our desire to work through grassroot non-government organisations in West
Bengal, the CS approached Debu Bandyopadhyay, former water resources secretary, to
identify an effective organisation through whom the pilot project could be implemented.
The Institute for Motivating Self-Employment (IMSE), a Calcutta based organisation was
identified as the local partner by him.
A visit to Calcutta was then organised followed by a visit to arsenic-affected villages
in November 1999. Accompanying Athavale and a CSE employee of the CS, was Dunglena, former
secretary, public works department, government of Mizoram. A member of the NWHN advisory
committee, Dunglena has been promoting rooftop rainwater harvesting in Mizoram.
At this point in time the options available for dealing
with arsenic included:
a) Roof water
harvesting and storage or artificial recharge;
b) Conversion of the commonly occurring village ponds (pukur)
into infiltration basins and installation of hand pump or shallow tubewell nearby; and
c) Construction of a hygienic
openwell to tap the phreatic aquifer.
During the visit to Deganga block of North 24 Parganas, the team visited two villages,
Kamdev Kati and Ambika Nagar, to assess the extent of problem confronted by the villagers
and also identify the villages for the pilot project. People in these villages have given
up hope for any amicable solution to the existing problem.
A visit to the villages ruled out two of the options mentioned above. There were no tin
or (Galvanised Iron)GI sheet roofs on the houses. The roofs are either tiled or thatched.
It was felt that although rooftop water harvesting can be implemented with modified
gutters, this could be deferred for the time being. With the water table in the villages
being shallow, the option of recharging near a hand pump or converting a pukur in an
infiltration basin was not considered appropriate for this area.
The result of
drinking water with arsenic
The construction of sanitary dugwells thus seemed
to be the appropriate strategy to pursue in the region. The area has top clay layer till
about 6 m depth, underlined by a sand bed which is the first aquifer. As the water table
is high, the maximum depth of the well would be about 10 m. At this depth, the water
available would be comparatively free of arsenic, since it is not found in phreatic
aquifers. Even if it has arsenic beyond the permissible limit, it will be oxidised and
thus it will coprecipitate with the iron when exposed to aeration in an open well.
Interaction with the villagers revealed that
microbiological contamination in the water from the dugwells was a major fear amongst
villagers. Responding to their apprehensions, arrangements have been made to prevent
biological contamination. Says Athavale, "Removal of bacteriological contamination
nowadays is much easier than removal of arsenic from water."
A parapet wall and a circular cement path around
the well will be constructed. A grill on top of the well would restrict people from direct
withdrawal of water, at the same time exposing the water to aeration. A water pump would
be installed along with a pipe, which would be connected to an overhead tank. Water from
the well would be only used for drinking and cooking purposes. Chlorination would be
undertaken if necessary.
The grassroots worker by virtue of staying in
close contact with the villagers will help in establishing rapport with the villagers and
sensitize the community, resulting in the formation of village level institutions which
can then monitor the progress of the programme.During the second visit to the identified
villages in January, the team was shown an old well near the temple.
The water from the well was tested for arsenic
presence and also to confirm the hypothesis that water in sanitary dugwells would be
arseni-free. The result of the test confirmed that the level of arsenic in water is well
below the permissible level.
For effective implementation of the project,
Biplab Halim, executive director of IMSE opined that discussions at various levels-sabhapati,
block development officer, pradhan and others, need to be organised. He emphasized
that mass awareness should be the entry point activity of the project in each of the
selected villages and proposed that a grassroots worker be placed at the Deganga block to
oversee the project.
|The arsenic effect
Tubewells with arsenic contaminated water is the main
source of water for the entire village at Kamdev Kati, in Kolsur panchayat of
Deganga block (about 120 km from Calcutta) in 24 Parganas North of West Bengal. The affect
of consuming water with high levels of arsenic is physiologically and psychologically
apparent amongst the villagers. A number of tubewells in the village contain arsenic way
above permissible levels. According to the Bureau of Indian Standards, the permissible
level of arsenic in drinking water is 0.05 milligram per litre.
The plight of the villagers is pathetic. Kamala
Mondal, a vegetable vendor and a resident of Kamdev Kati is a victim of the arsenic
menace. She is suffering from dispigmentation of the entire body, boils on the limbs,
keratosis (which appears like callused skin protrusions on palms and soles) and burning
sensation through the body. This has led her to being socially ostracized from her own
immediate family. She is not isolated in her experience: a substantial number of people
are suffering from the same ailment with differences in intensity.
Ambika Nagar is yet another severely affected
village in Deganga Block. The Chandra Pals family in Ambika Nagar is recognized for the
tragedy they are facing due to consuming the contaminated water. The status of the family
has drastically changed after the death of the eldest son due to arsenicosis. The younger
son has a similar future as he too is in a critical situation.
In the early eighties, cases of arsenical
dermatitis were reported from some districts of West Bengal. Analysis of water samples
revealed that the groundwater was contaminated with arsenic in these villages. According
to a latest survey, 1312 mouzas (revenue villages), 15 non-municipal/outer growths
in 65 blocks and 9 municipalities of Malda, Murshidabad, Burdwan, Hooghly, Nadia, North 24
Parganas, South 24 Parganas and Howrah districts have dangerous levels of arsenic in their
A total population of 5.36 million in these 8
districts is exposed to arsenic through groundwater use. This accounts for 7.87% of the
states population. Due to continuous movement of groundwater and peculiar
geochemical conditions, the extent of the problem may increase with passage of time.