Kolkata water profile: City of joy weeps for water
Adversity in spite of abundance. That’s how Kolkata’s water situation can be summed up. The city
has access to plenty of water, but its worn-out delivery network results in inequitable distribution.
Worse, drinking water gets contaminated, resulting in frequent outbreaks of water-borne diseases…
Kolkata (formerly Calcutta) was founded in the late 1600s by the British settlers who arrived with the East
India Company. The city probably derives its name from Kalikata, one of the three villages on which it came
up, which was famous for a temple dedicated to Goddess Kali.
The city has a history spanning over three centuries and was the capital of British India from 1773 to 1911.
Over the years, Kolkata, , which is the capital of West Bengal, has grown manifold to become one of the
biggest cities in the world.
The latest expansion of the city limits took place after the Kolkata Municipal Corporation Act, 1983, was
passed. It included the municipalities of South Suburban, Garden Reach and Jadavpur within the Kolkata
Municipal Corporation’s jurisdiction, which now spreads over 18,733 hectares, consisting of 141 wards.
River Hooghly flows past the western part of Kolkata and the South 24 Parganas district forms the southern
and southeastern boundary. The North 24 Parganas forms the eastern and northern limits of the city.
Inadequate civic infrastructure
The civic infrastructure of the metropolitan area is not adequate to cater to the city’s growing population.
Unplanned development for the better part of the city's three centuries of existence has taken its toll.
The shortage of funds and
low revenue generation has
also affected development
work. Housing shortage has
resulted in the growth of
slums. Roads are few while
the traffic has increased
tremendously. Public
transportation is extremely
crowded. Sanitation, water
supply, pollution, health,
access to education and the
state of the economy are
major areas of concern.
The demographic density during 1981 was 22,260 person per sq km and during 1991 this rose to 23,670
persons per sq km in Kolkata.
WATER SUPPLY STATUS
Paradoxical situation1
Water scarcity in a city like Kolkata, which is situated in the lower reaches of one of the world’s largest delta
regions, may seem paradoxical. Though Kolkata has a fairly abundant source of surface water close by, the
community water supply system suffers from problems of poor maintenance, inequitable distribution and poor
quality management.
Kolkata residents get more water than their counterparts in other metropolitan cities. But, the abysmal quality
of water makes it a serious health hazard. An inadequate and worn-out distribution system coupled with
poverty and squalor in the innumerable slums and squatter colonies adds to the problem. As a result,
outbreaks of waterborne diseases and epidemics because of faecal pollution of drinking water are alarmingly
frequent in the city.
Water sources
The residents get their water supply from three
main sources:
 The KMC supplies treated water through an
underground pipeline network
 The roadside public bore wells that KMC has
dug
 The innumerable private bore wells that the
residents have dug up.
Though there is no dearth of water, the city does
not have enough resources to treat it or maintain
and manage the distribution system.
Enough water, claim authorities
The conference of secretaries, chief engineers and heads of implementing agencies in-charge of urban water
supply and sanitation held in May, 1989, had recommended a minimum per capita water supply of 150 litres
per day, including losses for Class I cities.
Earlier, the National Commission on Urbanisation had recommended that in the urban areas, the objective
should be to have a provision of at least 70 litres of water per capita per day for domestic requirements.
KMC’s Basic Development Plan for Kolkata, released in 1966, recommended a provision of 272 litres per
capita per day in Kolkata and Howrah municipal areas and 217 litres per capita per day for the rest of the
metropolitan district.
The municipal corporation presently supplies about 750-800 million litres per day (MLD) from its surface water
sources and 136 MLD from groundwater sources. Additionally, it also supplies 300 MLD of unfiltered, but
chlorinated water.
KMC now claims to supply over 250 litres of water per day to residents in its jurisdiction. In other words, at
least on paper, there is no shortfall even after taking into account the increase in population since 1981.
But the stats don’t add up…
KMC’s statistical figures, however, conveniently cover
up the hardships that most residents face due to
inequitable distribution. Moreover, at least 25-35 per
cent of the water supplied goes waste due to
leakages in the worn-out pipes, public taps and stand
posts.
Kolkata has some 8,000 stand posts in all and about
60 per cent of the water that these outlets supply is
wasted (see picture). Yet, there is no alternative, as
these stand posts are the only source of water for the
poor.
ts supply
ty’s poor
The rather high per capita water supply figure needs to be considered from another angle also. About 40-50
per cent of the total population in Kolkata lives in slums or squatter colonies and has to collect water from
stand posts only. Another 20-25 per cent is served by single tap connections in their houses. Thus, the actual
figure is unlikely to go beyond 60-80 litres per day.
It is evident that a large volume of water is being wasted due to improper management. Considering the
extremely poor level of water supply in majority of municipalities and non-municipal urban areas in the Kolkata
Metropolitan Development Authority areas outside KMC, the approach appears to be lop-sided.
History of water supply in Kolkata
Potable water supply began in Kolkata in 1869 with the installation of a slow sand filtration unit having a
capacity of 6 million gallons per day (mgd) at Palta. The plant’s capacity was raised, in stages, to 32 mgd by
1911.
The city expanded rapidly between 1948 and 1966 and had to cater to a huge influx of people for various
reasons, including the Second World War, the infamous Bengal famine, Independence and partition of
Bengal. Large settlements grew on both side of River Hooghly in the Gangetic delta. The Kolkata Municipal
Authority (KMA) looked after the civic needs of a population of more than 14.6 million, settled over 178,500
hectares.
The first water works at Palta for supply of 27.28 million litres of filtered water every day to a population of 0.4
million was constructed in 1870 for a community water supply scheme with a supply of 68 litres per capita per
day.
Today, the Palta Water Works, which is situated on 195 hectares along the riverfront, supplies about 780
million litres of water every day on an average. The water from Palta flows through four pipes (of 1 to 1.8 m in
diameter) to the reservoirs and pumping station at Tallah. From Tallah the water is distributed to the city by
four zonal mains, which feed the vast distribution network measuring about 3,800 kilometres in length.
However, the Tallah-Palta water supply system is not enough to serve the consumers in the southern parts of
the city, particularly in areas that have been recently added to the Kolkata Municipal Corporation like
Tollygunj, Garden Reach, South Suburban and Jadavpur.
Considering the low pressure and inadequate supply in these areas, supplementary arrangement from local
groundwater sources is made to augment the supply. With the setting up of Garden Reach works in 1982 to
supply water to these areas, the critical water supply distribution system in South Kolkata is expected to
improve. Presently, Garden Reach supplies 50 million litres per day, which is expected to rise to 217 million
litres per day when the construction of various units of the water works is completed.
Present status
According to B K Maiti, Deputy Chief
Engineer, Water Supply Dept, KMC, the
demand as on 2004 is around 334
million gallons per day (MGD) and
supply from surface and groundwater
source is about 320 MGD with a gap of
10 MGD.
In 2002, KMC supplied 1062.18 MLD of
water, falling short of the demand by
almost 189 MLD. However, in 2003, the
average supply rose to 1262.52 MLD, meeting nearly 90 per cent of the requirement. Keeping the needs of
the growing population in mind, KMC has undertaken several capacity enhancement and upgradation
programmes and hopes to exceed the demand by 2005.
The New Palta Water Works at Indira Gandhi Water Treatment Plant is a notable step in this process. The
378 MLD water generation project, which was commissioned in July 2004, further augments Palta’s capacity
by 226.8 MLD. This, along with the increased supply from Garden Reach Water Works, will increase the per
capita water supply to 234 litres per day from the present 202 litres per day.
Kolkata’s water supply at a glance:
Total daily potable water supply (in million litres)
1350
Per capita availability of water per day (in litres)
202
No. of tubewells
Big diameter
Small diameter
455
7875
No. of connections
Domestic
Industrial and commercial
2,12,000
25,000
Public Access
Stand posts (in numbers)
Street hydrants that use unfiltered water (in numbers)
17,019
2,000
No. of reservoirs
7
Present
14
Under construction
96
Combined capacity (in million gallon)
After the commissioning of the New Palta Water Works, the per capita water availability in Kolkata
will be 234 litres per day
Source: KMC
Problems that Palta Water Works faced
Rapid growth of population in the city placed a huge burden on the plant. Increased salinity in River Hooghly,
excessive leakage through the old distribution network and loss of pressure head as water had to be
conveyed over long distances were among the chief problems that the plant faced. But, with the construction
of Garakka Barrage and diversion of sweet water to River Hooghly, there has been marked reduction in the
salinity of river water. With the establishment of Kolkata Metropolitan Development Authority (KMDA),
development work for improvement of surface water to KMC and other settlements in the Kolkata
Metropolitan Area have been undertaken.
The plant, which had an initial capacity of 22.68 million litres per day (MLD), generated filtered water through
sedimentation in pre and final settling tanks and slow sand filtration in the Old Series of 12 filter beds. Another
24 beds, each with a capacity of 3.78 MLD, were added between 1888-1893. In 1905, filter beds with 7.56
MLD capacity, called New Series, was started. Between 1920 and 1936 when 17 beds of 11.34 MLD capacity
and one bed of 7.56 MLD capacity, called Extension Series, were introduced. With an output of 491.4 MLD
the plant seems to have perennial capacity to serve. In 1952, a 12-bed rapid gravity unit with a capacity of
75.6 MLD was added. This process helped in reducing the sedimentation time. In 1968, another 226.8 MLD
rapid gravity filtration unit was added.
Slow sand filter
The slow sand filtration system is an effective and reliable system that does not require daily washing. A
single bed can work up to 100 to 200 days. Formation of a biological mat soon after effective charging
removes turbidity, colour and microbes. The biological mat on the surface removes 95 per cent of the colloidal
clay particles, which are hideouts for microbes. The process requires much less chlorine to disinfect water.
Regular scrapping of about 10 to 20 millimetres of the top sand layer once in every 100 days keeps the beds
ready for reuse.
Water supply in suburbs
The standard of services and quantity of supply in the municipal and non-municipal urban areas outside KMC
compares very poorly with that in the city area. Whereas the basic development plan envisaged a supply of
227 litre per capita day with the average rate of supply being only 56 litre per capita per day with the average
rate of supply being only 56 litres per capita per day.
In 1981, the total water demand of two municipal corporations and 33 municipalities of the Kolkata Urban
Agglomeration was 1532 MLD. By 2001, it rose to 2386 MLD. The gap between the existing supply and
demand is considerable. The organisation’s capacity and infrastructure of the municipality outside KMC are
so poor that the existing supply in most of these municipalities is only a fraction of the optimum possible
supply from the installed capacities of water supply systems in those municipalities. In the non-municipal
urban areas, there is no organised public water supply system whatsoever.
Distribution system
The most critical aspect of Kolkata’s community water supply is the state of its distribution system. The
number of zonal mains is inadequate and the greater part of the network has long outlived its natural life and
is in an advanced stage of dilapidation. Major and minor tank leaks are endemic and bursting of major pipes
is frequent. These factors are the principal causes of not only substantial loss of water in transit but also gross
pollution and deterioration in water quality.
Construction of Metro railway and other public utility services has damaged and aggravated the decaying
water distribution system in the city.
Water charges
According to KMC the production cost for 1000 litre of water is about Rs 3.11 and the selling cost is Rs 3 for
domestic purposes as on 2003. The Kolkata Municipal Corporation Act, 1980, empowers the corporation to
impose fees at such rates as would be determined by the regulations made in this regard for supply of water
to premises for domestic purposes. The KMC decision to impose water fees on 27.31 per cent of the 152,578
holdings in the city as on 31.08.85 is encouraging. This fee at present is charged on holdings, whose annual
valuation is above Rs 2990, so that the economically weaker section are exempted from paying the tax.
KMC to collect water tax
After withdrawal of subsidy on water supply in Kolkata, the citizens collectively may have to pay about Rs 600
million annually to the civic authorities. Under directions of the Asian Development Bank (ADB), KMC will levy
charges for water supply, sewerage and drainage charges to recover costs. Water supply in the city is
subsidised under the current system. In 2001-02, Rs 757.1 million was spent in generation and supply of
filtered water in KMC areas, while only Rs 183 million was recovered as water charges. The KMC supplies an
average of 250 MGD to the city, at a cost of Rs 10 per kilolitre. The supply works out to an average of 45 litres
per head per day. Presently, the water charge is based on the size of the ferrule in a house – homes half-inch
ferrules are charged Rs 480 per year (to go up to Rs 600) and one-inch ferrule connections at the rate of Rs
790 (to go to Rs 1,000). For bulk users of water, consuming over 1000 kilolitres per day, water meters are
installed. Metered water supply is to be charged at the rate of Rs 3 per kilolitre for domestic consumers, while
industrial and commercial connections are to cost Rs 15 per kilolitre. According to a survey, this would
generate a surplus of Rs 700- 800 million per year. For sewerage and drainage, a 50 per cent surcharge will
be imposed on water tariff for domestic consumers, which will be 80 per cent for industrial consumers. ‘In
addition, 15 per cent of the consolidate rate charge will be allocated for supporting water supply, 15 per cent
of sewerage and drainage and 15 per cent of SWM,’ the ADB report stated. (The Times of India, November
26, 2002)
Water quality and health risks
The city has been notorious for the epidemics of cholera and other water-borne diseases for long. A
newspaper report published on September 29, 1825 states: ‘…the terrible way in which Cholera has broken
out in Kolkata is beyond all description… it is very difficult to ascertain the number of people that are dying
every day in Kolkata, we have heard that in the week the average number of deaths may be 400. It would be
no exaggeration but on the side of under estimation.’
The incidence of cholera rose sharply with the increasing population of the city in the late 1940s and 1950s
due to influx of refugees. In 1958, there were 4,895 cases of cholera and 1,756 deaths were reported.
Though the city now witnesses fewer cholera
epidemics, during the 1970s and 1980s, the
city witnessed outbreaks of gastroenteritis,
hepatitis, dysentery and other water borne
diseases.
Experts believe that though the water supply
from Palta is safe after the treatment it
undergoes, it gets contaminated as it passes
through the underground distribution network.
The fear of water-borne disease striking is the
greatest during the monsoons. The floods increase the chances of surface water being contaminated by
sewage and garbage washings. The contaminated water then enters the distribution system through
breaches in the distribution network.
Special mention may be made here of the unfiltered water supply of 340 MLD drawn from the river and
distribution through 1,120 kilometres of mains, meant chiefly for fire fighting, street washing, water closet
flushing, etc. The city’s poor also use this untreated water for domestic uses. It was a major factor behind the
cholera epidemics that afflicted Kolkata till 1960s. Chlorination of unfiltered water on the basis of a report
submitted by the All India Institute of Hygiene & Public Health has dramatically reduced the cases from 1963
onwards.
A survey, conducted by the Federation of Consumers Association (FCA), West Bengal and Better Business
Bureau, a NGO found that 80 per cent of the 1,000 water samples collected from all municipal wards of the
city contain E.coli (bacteria that indicates the presence of faecal matter), Salmonella (responsible for
typhoid), Shigella (bacteria that causes dysentery) and Vibrio (causes cholera). The scenario is the worst in
the Kasba-Ballygunj area. Though chlorinating the water could have killed these microbes, not the slightest
trace of Chlorine was found even in a single sample.
(Source: The Telegraph, April 14, 2003)
Drinking water quality in Kolkata9
A recent study conducted by Better Business Bureau
(BBB) concluded that the quality of water supplied by
KMC is good at the source (where it is treated and
pumped from), but gets contaminated on its way
before it reaches the consumers.
The researchers examined 100 samples out of a total
of 1000 samples collected from nine zones.
The study revealed:



87 per cent of water reservoirs serving residential buildings had high traces of human waste
Water collected from 63 per cent of taps showed a high level of faecal contamination, while 20 per
cent of water samples collected from the city's hospitals were also polluted.
Roughly one-fifth of the deep wells and hand pumps maintained by the Kolkata Municipal
Corporation also had traces of excrement.
The zone-wise analysis is as below:
Zone-wise analysis of water samples
Zone
Areas included
no
Zone 1 Extends from Lake Market in North to
Garia in South, Raja S.C.Mallick Rd. in
East to Deshpran Sasmal Rd. in West.
Zone 2 Extends from Taratal - Majerhut in the
North to Biren Roy Road.- Barisha in South
& Banamali Laskar Rs. - Behala in the
West to Deshpran Sasmal Rd. in the East.
Zone 3
Zone 4
Zone 5
Zone 6
Zone 7
Zone 8
Extends from Kasba - Ballygaunge in the
North to Garia in the South, E.M. Bypass in
the East upto Raja S.C.Mallik Road,
Garihat crossing & NSC Bose Road S.C.
Mallick Rd. in the West.
The zone is bounded by Circus Avenue Park Circus - Tapsia Rd. in the North and
Despriya Park - Ballygaunge in the South,
E.M. Bypass in the East and S.P.
Mukherjee Rd. in the West.
The zone is bounded by Lenin Sarani,
Cannel South Road in the North, A.J.C,
Bose Road ... Tapsia Rd. in the South,
Maidan in the West to Dhapa ...
E.M.Bypass in the East.
The zone is bounded by Belghachia Rd. ,
Pati Pukur , Lake Town in the north to
Sealdah , Beliaghata Road in the South ,
A.P.C. Road in the West to Nazrul Isam
Sarani , Ultadanga Road , National Medical
College in the East, Tala in the South ,
Hoogly River in the West and Seth Bagan
.. Dum Dum Road in the East.
The zone is bounded by Shyam Bazar
Crossing of Belghachiya road in the north
to Lenin Sarani in the South , Strand Road,
Barabazar in the West and Acharya P.C.
Road in the East.
Bounded by Sithi K.C. Roy road in the
north, Belgachiya, Tala in the South,
Hoogly in the West and Seth Bagan Dum
Dum road in the East.
Test result of
groundwater samples
Arsenic closes to
permissible limit
Arsenic closes to
permissible limit
Turbidity, TDS and iron
were present in higher
than permissible limits.
Arsenic closes to
permissible limit
Turbidity, TDS and iron
were present in higher
than permissible limits.
In Zone 5 and 6 both
KMC and private bore
wells were found to be
totally free from any
chemical contamination.
Test result of KMC pipe
water supply.
50 per cent of samples
have high hardness and
iron content.
3 per cent of samples
displayed Arsenic higher
than acceptable limit. Here
groundwater also Arsenic,
hence there might be
contamination.
Free from chemical
contamination.
Turbidity, Hardness and
iron are above permissible
limit in 2 per cent to 20 per
cent of the samples.
Free from chemical
contamination.
Free from chemical
contamination.
Free from chemical
contamination. Turbidity,
Hardness and iron are
above permissible limit in
2 per cent to 20 per cent of
the samples.
Zone 9
The zone extends from eastern bank of
Hoogly, Strand road (north) to Taratala
road, Garden Reach (south), Taratala
Road (west) to Despran Sasmal road
(east)
Turbidity, TDS and iron
were present in higher
than permissible limits.
Turbidity, Hardness and
iron are above permissible
limit in 2 per cent to 20 per
cent of the samples.
Source: Better Business Bureau
Arsenic in Kolkata
The civic authorities have sealed the deep tubewells at Victoria Memorial Hall after all the test reports from
the laboratories of the School of Tropical Medicine, Kolkata Municipal Corporation (KMC) and the Department
of Public Health Engineers confirmed arsenic contamination beyond permissible limits. The concentration of
arsenic was found to be four times higher than WHO prescribed benchmark. The KMC has made alternative
arrangements to supply safe water to Victoria. (Source: The Telegraph, August, 1, 2003)
GROUNDWATER SCENARIO IN KOLKATA
History of groundwater extraction 10
The first move to tap sub-surface water in Kolkata was made as early as 1804. Between 1918 and 1940,
nearly 200 medium diameter tubewells with an average yield of 27,275 litres per hour were set up in what is
known today as Kokata Metorpolitan District. Many more tubewells were drilled during the World War II to
ensure water supply during emergency.
The population growth after partition made it necessary to install heavy-duty tubewells to supplement TallahPalta water supply, particularly in southern Kolkata. Though initially conceived as an emergency and stopgap
measure, the system has now come to stay for good.
Presently, Kolkata Municipal Corporation runs 455 large diameter deep tubewells and 7825 small diameter
tubewells contributing about 136 million litres of water per day. An unaccounted number of deep tubewells by
private industries and business establishments, housing estates and highrise apartment blocks have also
been functioning. There are also several thousand small diameter tubewells owned by private households.
Groundwater resource
Due to large-scale withdrawal of groundwater from the confined aquifers, a depression of piezometric surface
in Central and South Central Kolkata has developed. The magnitude of the depression is 6-8 metres, and has
developed over a period of about 40 years (1958-98) in the core sector covering Narkeldanga- Park Circus –
Bhowanipur.
As a result, the general southerly flow in the confined aquifers has become radial in a much larger area
surrounding the cone of depression. The central part of Kolkata Municipal Corporation area is drawing water
from all directions resulting in its radial flow. The total quantity entering form the immediate vicinity of KMC
area into the central depression zone comes to 204 MLD in the absence of precise Census data of the
withdrawal structures it is difficult to evaluate precise ground water draft in KMC area.
Groundwater withdrawal status as on 1988
Source
Numbers Average discharge
Larger diameter tubewells
325
Small private tubewells (4.5
inch diameter)
4834
68 cubic metres
per hour
27 cubic metres
per hour
Assumed hours of
pumping
7 hours
Total per day
withdrawal
153 MLD
7 hours
914 MLD
Shallow hand pumps
12,000
0.68 cubic metres
Total
Source: Central Ground Water Board (CGWB)
7 hours
56.7 MLD
1123.70 MLD
According to the Central Ground Water Board (CGWB) the withdrawal is 1123.70 MLD but the inflow is only
204 MLD, which results in the fall in the piezometric head. In 2003-04 according to KMC the number of larger
diameter tubewells has increased to 455, and smaller diameter borewells to 9875 and the number of shallow
hand pumps is 17,019. Hence the current groundwater based on the withdrawal figure by CGWB will be about
2120.5 MLD. Hence it is clear that between 1998 and 2003 the groundwater extraction has increased by 1.9
times in five years period.
Groundwater quality (CGWB)
The chemical quality of groundwater in the Kolkata area in the depth range of 60-250 mbgl is depicted
through isochloride and isoconductance maps (based on the data for the April 1999 to understand the nature
of chemical characteristics of groundwater. From the isochloride contour map it is seen that in the extreme
northern part (North of Shyambazar area) chloride concentration in groundwater is above 500 mg/l. Similarly
in the western part of Alipur i.e. in Garden Reach and adjacent area, the chloride concentration in
groundwater is above 500 mg/l. In the area lying between Belgachia and Park Street, chloride concentration
in groundwater is between 250 and 500 mg/l. In Garia-Jadavpur sector, chloride concentration in groundwater
is within 250 mg/l.
From isoconductance map, it is seen that extreme northern part of KMC area isoconductance value is above
2000 micro siemen/ cm at 250 C. In Sealdah-Beleghata-Narkeldanaga area and Garia-Putiari-Behala area in
conductance value is between 1000-1500 micro siemen/ cm at 250 C. In Garden Reach area, isoconductance
value is more than 1000 micro siemen/cm chemical character.
Tanneries situated in the eastern part of Kolkata (Tangra, Tiljala, Tapsia, etc.) are a cause for concern as
industrial effluents from these units pollute the Bheris, wetlands and agricultural fields. Toxic trace elements
like, Chromium and Cobalt are found (above 0.01 mg/l) in the shallow aquifer (within 20 m bgl) in the area,
which is not suitable for drinking purposes. However analysis of water samples from deeper aquifer (80 to
200m depth) shows that concentration of chromium, cobalt and other heavy metals is below permissible limit.
Hydro-geological consequences of unplanned groundwater extraction 2
The impact of groundwater exploitation needs closer examination. Tests reveal that northern parts of Kolkata
Metropolitan District have much greater value of groundwater transmissivity. Yet, it is southern Kolkata that is
most reliant on groundwater sources. This lower availability and greater exploitation of groundwater produces
consequences reflected in a number of surveys relating to the level of piezometric surface.
A survey conducted in 1956 showed the depth of piezometric surface in the post-monsoon period descending
from 4.27 metres in the northern suburbs to 5.46 metres in the southern city area. A much wider survey in
1985 showed the piezometric surface to be only 1.78 to 2.65 metres in the far north and 11 to 13.38 metres in
the south-central area.
By collating the results of two surveys, a progressive decline in the groundwater levels towards the south can
be seen. This clearly indicates that the southern part of KMD has a much lower potential for groundwater
exploitation. More crucial, however, is the overall decline in such water levels all over the KMD. At any given
point, 1985 level was markedly lower than the 1956, the extent varying from 3.84 meters to 9.75 meters.
This decline has obviously been caused by reckless and unplanned exploitation of groundwater resources
during the last three decades. This can lead to gradual subsistence in land in the deltaic area as has been
seen in Texas, Bangkok and some cities in China.
As has been pointed out in the Basic Development plan, the poor quality of groundwater should also be taken
into account in developing any rational plan of water resource management for the Kolkata Metropolitan
District especially in the eastern and southern parts.
Drainage and sewerage
Kolkata has been plagued by severe problems of drainage due to its geographical location. The city has been
notorious for water logging during the rainy months ever since it was founded. Situated between the tidal river
Hooghly on the west and surrounded by swamps and marshes on the east and south, the city has suffered
chronic drainage congestion during the monsoons, when the Hooghly River, the tidal creek, and the swamps
over flow. Lack of drainage and the resulting unhealthy conditions particularly during the hot and humid
monsoon moths makes the city’s environment appalling.
The situation was so bad during the early years that a large number of people succumbed during the rains,
every year, throughout the eighteenth century. This state of affairs continued upto the middle of 19 th century
when efforts were initiated to improve the drainage.
The drainage systems of the city have been designed as a combined system for the disposal of storm water
as well as sewage and dry weather flow. The core of the system had been proposed in 1855 and constructed
during 1860-1875 to cover originally an area of 1920 hectares. Subsequent modifications and augmentations
during 1891-1906 brought another 3200 hectares in the newer southern areas of the city under the sewerage
system. The sewage from the combined drainage system flowed into the creek of the tidal river, Vidyadhari,
on the east of the city.
Burdened with the entire city’s drainage system River Vidyadhari began to show signs of rapid deterioration.
In 1943, a new scheme for both the outfall and the internal drainage system was commissioned. Since then,
the system has undergone major modifications and expansion to meet the city’s rapid growth. The Masterplan
prepared by the WHO for the Kolkata Metropolitan District in the 1960s dealt with these issues and has
provided the guiding framework since then.
Geographical and hydrological factors
Kolkata’s drainage problem is aggravated by the topography (west to east- away from River Hooghly) and the
tidal nature of the rivers and streams around it. The premature reclamation, which interrupted the natural land
building process, resulted in the general ground elevation, which is lower that the high water level in Hooghly.
Discharge of drainage, therefore would require constructing deep underground drains and pumping out the
waste water at very high capacity and recurring costs. The tidal rise of water level in the water bodies (3
metres during winter and 5 meters during monsoon) imposes yet another constraint on the speedy and
effective disposal of Kolkata’s drainage.
Water bodies of Kolkata
Water bodies of Kolkata requires urgent management
initiatives, says Mohit Ray of Vasundhara3, NGO that
works for wetland development. According to Ray, the
water bodies are water resources for poor people.
Hence, efforts to improve people’s quality of life must
include a plan to use these water bodies wisely. The
encroachment and filling of water bodies in the urban
areas are taking place because of lack of planning,
information and management.
There is no database on these 3,000 water bodies,
which serve about 400,000 people. There are no studies
on management issues of urban and peri-urban water
bodies, which are considered as a special group of
natural resources.
Kolkata Municipal Corporation does not have any specific section to deal with these water bodies.
Conservation efforts for these water bodies become useless if there is no programme for its future
preservation. Kolkata needs a special institution for proper management of these urban water resources.
Kolkata still has about 3,000 ponds, which provide about 15 per cent of water requirement of the city but no
city planning exercise has ever mentioned these important water resources. Vasundhara has been working to
spread awareness through direct participation and research for last several years.
Inadequate treatment capacity
It is to be regretted that Kolkata does not yet have a full-fledged sewage treatment plant. There is only a
primary treatment plant at Bantala to treat a part of the sewage. It contains two sediments tanks, each
containing two sedimentation tanks, each having a capacity of 273 million litres per day, two sludge pumphouse and 12 sludge lagoons. Even this plant has ceased to function. It needs to be recommissioned urgently
and placed under the Kolkata Municipal Corporation. At present, it is being operated by the irrigation and
waterways directorate.
Sewage-fed aquaculture in wetlands
Kolkata has a unique system for the utilisation of sewage in the eastern suburbs of the city. For a long time
now, the vast wetland there has supported sewage fed fisheries, which supply a considerable quantity of fish
to the Kolkata market. Sewage irrigation is also practiced to produce vegetables for bulk supply to the city.
According to Dhrubajyoti Ghosh, the wetland produces 10,000 tonnes of fresh and relatively cheaper fish and
147 tonnes of vegetables daily. Bonani Kakkar of PUBLIC, a local NGO, says, “Since the wetland is near to
Kolkata, the vegetables and fish are available at a cheaper rate, due to less transportation cost.”
The wetlands in Kolkata originated largely from the inter-distributory marshes, created by the shifting of the
main river, Hooghly. It is estimated that out of 10,120 hectares of wetland existing in 1945, an area of about
4700 hectares of land were used for sewage fed fisheries that yielded an average of 8.40 quintals per
hectare. By 1985, the wetland area under sewage fed fisheries has declined to 3,200 hectare.
The domestic sewage generated by the city, estimated to be 1394.42 MLD, gets partly purified as it flows
through the east Kolkata wetlands by means of a system of principal and ancillary channels. These flows are
utilised in sewage-fed fisheries having an average production of about 3.44 MT/ hectares/year and vegetable
production. At present about 3898.27 hectares (out of this 697.72 hectares are seasonal) are covered with
sewage-fed fisheries. There are about 58 fisheries in east Kolkata wetland area, providing direct employment
to 15,700 people and indirect employment to 23,600. The employment generation is for the population living
below the poverty line. The fish are marketed through different auction markets. Chingrighata market is the
most important one with an average daily sale of 12.6 metric tonnes.
East Kolkata wetland
The East Kolkata wetlands is an urban facility that treats the
city’s huge wastewater and utilises the treated water for
pisciculture and agriculture, through recovery of wastewater
nutrients in an efficient manner. Here, wastewater is used in
fisheries and agriculture covering about 12,500 hectares
that has been designated as conservation area by an order
of the Kolkata high court. The conservation area, also
described as the waste recycling region, has three major
sub-regions of economic activity – fishponds (bheris),
garbage farms and paddy lands.
The smallest recycling sub-region on the edge of the city
covers the vegetable fields that grow vegetables on a
garbage substrate and are uniquely planned with alternate bands of garbage filled lands and elongated
trench-like ponds locally known as jheels. Sewage is detained in these jheels for sometime, after which the
treated effluent is used for irrigating the garbage fields for growing vegetables. In the fishponds, the city’s
wastewater is made to flow through a network of drainage channels.
The wastewater fishponds act as solar reactors and complete most of their biochemical reactions with the
help of solar energy. Reduction of BOD (biochemical oxygen demand) takes place due to the unique
phenomenon of algae-bacteria symbiosis where energy is drawn from algal photosynthesis. In this way,
requirement and consumption of energy remains the minimum. Unlike conventional mechanical sewage
treatment plants, wastewater ponds can ensure efficient removal of coliforms that are prone to be pathogenic
(Turning Around, 1996).
The fishponds drain out the used water to irrigate paddy fields. The fishpond ecosystem of east Kolkata is one
of the rare examples of environmental protection and development management where the fish producers
and farmers have adopted a complex ecological process for mastering the resource recovery activities.
What is remarkable is that the fish yield rate attained is among the best in any freshwater pisciculture in the
country. The east Kolkata wetland has the largest number of sewage-fed fishponds in the world that are
located in one place. The knowledge that has emerged based on traditional skill, enterprise and innovation
provides an alternative to the conventional option of wastewater treatment by an ecologically sustainable and
wise use of wetlands. Here the task of reusing nutrients is linked with the enhancement of food security and
development of livelihood of the local community using nutrient rich effluent in fisheries and agriculture. The
conventional sewage treatment plant is considered an externality in the basic social and economic of Kolkata
and its fringe.
Interestingly, a large part of this ‘folk’ technology is part of an oral tradition. New generation environmentfriendly engineering has been quick to incorporate the advantages of natural biological processes and
principles of ecological regulation. In this context, using wetland functions for reducing wastewater pollution
and reuse of nutrients is an example of an effort that has opened new areas of research and application in
other parts of the world too.
In 1980, on an initiative of the Government of West Bengal, the wetland area and its reuse practices were
assessed. By 1983, the first scientific document on this ecosystem was published which enabled the rest of
the world to know about the ecological significance of this outstanding wetland area. In 1985, the map of the
waste recycling region that forms the basis of all planning and development activities on this wetland area
was prepared.
In the same year, the state government put forward a proposal to introduce a resource efficient stabilisation
tank (REST) system for the treatment and reuse of city sewage. The Ganga Project Directorate as an
alternative to conventional energy expensive and capital-intensive mechanical treatment plants accepted this.
A number of such projects under the Ganga Action Plan have now been completed and are working. Towards
the end of the eighties real estate interest reached a new high and there was a strong tendency to convert
water bodies and wetlands into housing complexes. To combat this, the Government of West Bengal initiated
a number of development control measures. For a comprehensive planning and development of the entire
region, a baseline document for management action plan using Ramsar guidelines has been completed.
Industrial pollution in wetland
A large number of small and medium scale industries
are availing of the drainage system laid by municipality
since last couple of decades to release their untreated
effluent. These drainage channels are linked with the
main outfall channels leading to the river Kulti. This
industrial wastewater can cause undesirable impact on
the fish and vegetables grown using the same. It is
imperative to identify such industrial units which
discharge contaminated effluent to bring them under the
purview of pollution control regulations. Common in-situ
effluent treatment plants for the polluting industries are
considered to be the likely solution to this emerging
problem.
Quality of wetland3
The report on Environmental scenario of sewage fed
fisheries of Kolkata, contains the results obtained from
analysis of the inlet and settled water of Captain Bhery,
which was collected by the Fisheries Department
fortnightly throughout the year. The pathogenic bacterial
count was found to be much less in settled water
compared with inlet water.
Sewage outflow from Chowbhaga pumping station11
The BOD in the raw sewage has been found to vary
between 30-116 mg/l while the same in the settled
ponds is as low as 2.1 –5.7 mg/l. COD also drastically
fell from a concentration of 150-180 mg/l to 84-97 mg/l. DO increased from 0.8 mg/l in the raw sewage to 3-12
mg/l in the settled ponds. pH at inlet points varied from 7.2 –8.2, but at the growing pond it was between 8.7 –
9.5.
Ammonical nitrogen and nitrate nitrogen concentrations in the inlet were 0.107 –0.32 and 0.52 –0.8 mg/l
respectively while the same in the settled ponds were 0.001 – 0.005 and 0.102 – 0.42 mg/l respectively.
Bioaccumulation of heavy metals in the sewage fed system was confirmed. Among the heavy metals, zinc
seems to be the dominant one with its concentration in the inlet being 0.9 mg/l, followed by lead (0.6 mg/l),
copper ( 0.2 mg/l), chromium ( 0.15 mg/l) and cadmium ( 0.02 mg/l).
However, presence of heavy metal in fish tissues was found to be insignificant. In spite of that, it has been
suggested that instead of allowing the raw wastewater to directly enter the fish ponds, as is sometimes done,
it should pass through a water hyacinth tank where some amount of heavy metals may be observed.
Regarding disease and parasites the, bhery fish are practically free from any major disease.
Rainwater harvesting in Kolkata
Rainwater harvesting will be an ideal option to prevent the alarming fall in the water level in the city. The study
of the rainfall pattern and sub surface geology shows that both storage and recharge methods can be
successful applied in the city.
Rainfall pattern in Kolkata
The city lies in a monsoon region, with most of its
average annual rainfall of 1500 mm falling from
June through September. Though winters are
mild, with an average January temperature of 19°
C (67° F), the temperature sometimes dips to 10°
C (50° F). From March through September,
Kolkata is hot and humid, with an average July
temperature of 29° C (85° F); in the months of
May and June the temperature may rise as high
as 38° C (100° F).
Water harvesting potential of the city
Kolkata Municipal Area = 187 sq km
Annual average rainfall = 1500 mm
Total rainwater falling over the city
= 187 x 1,000,000 x 1500
= 280,500,000,000 litres
= 768 MLD
Present water supply = 1209.6 MLD
Even if we assume 70 per cent of the area to be developed, 50 per cent of it to be roofed and we collect 70
per cent of the water falling over it, the quantity of rainwater that can be harvested works out to 188 MLD. This
is a sizeable quantity compared to current water supply.
How much water can be harvested from individual houses
If a house in Kolkata has a rooftop area of 100 sq m, one can harvest about 1,20,000 litres of water. The
formula for calculating the amount of rainwater that can be harvested is as follows.
Runoff =A x R x C
A=Area
R=Rainfall in millimetres
C=Runoff coefficient (0.8)
Here’s how:
Area (A)=100 m2
Rainfall = 1500 millimetres
Runoff coefficient = 0.8
Runoff (100 x 1500 x 0.8) = 1,20,000 litres
Storing rainwater
The design parameter for storage depends on the number of dry days and requirement. The details for
calculation an optimum storage tank is given below.
Rainy days in the city
The above graph shows that the number of dry spell or non-rainy days in a year is 200. So, we have to design
the size of our storage tank in such a way that during the dry periods, water is available for drinking purpose.
The below mentioned calculation can be applied to determine the size of the storage tank.
No. of persons in a household
No. of dry days in a year
Per capita consumption (lpcd)
Average annual rainfall (mm)
Rooftop area (sqm)
Runoff coefficient
Size of the storage tank
:
:
:
10
:
200
6
:
1500
:
20
:
0.80
10 x 200 x 6
= 12,000 litres
Check :
Water available from rooftop
:
1500 x 20 x 0.8
=
24,000
Hence, sufficient water is available to meet the demand of 12,000 litres
The storage tank can be ferrocement tank, plastic tank or brickwork tank. The tanks can be placed of surface
or below the ground level also.
Case study
Recharging in Kolkata
Recharging is also viable in Kolkata, but for recharging the under ground aquifers, knowledge of Hydrogeolgy
of the city is essential.
Hydrogeology of Kolkata2
A succession of quaternary sediments comprising clay, silt, fine to coarse sand and occasional gravel lie
underneath Kolkata. Below these sediments at depths beyond 296 m, there is a thick sequence of Pliocene
clay at least down to a depth of 614 m below the land surface. The thickness of the top clay bed varies from
place to place with an average thickness of around 40 m. The maximum thickness of over 80m of this bed is
encountered at Beleghata. The clay bed thins out to about 20m towards east of Kolkata. In the central part of
the city, the thickness of the top clay bed is over 50m.
Occurrence of groundwater is Kolkata is controlled by this geological set up. An aquiclude represented by
clay and silty clay with an average thickness of 40m occurs in the upper part of the sedimentary sequence
prevents natural recharge.
Where to divert the rainwater in North Kolkata and Howrah2
Sl
No.
Location
Sub-surface geology in meters
below ground level (mbgl)
Depth of the recharge well in mbgl
1
Akra Road
0-24 clay
50m
24 –32 fine sand
32- 48 clay
48- 104 coarse sand
2
Garden Reach
0-56 clay
60m
below 56 coarse sand
3
Hastings
0-32 m fine sand
32 – 56 m clay
Shallow recharge structures up to 32m
and deeper structures below 60 m
below 56 m coarse sand
4
Park Street
0-48 clay
50
Below 48 fine and coarse sand
5
Seal Lane
0-40 clay
40
below 40 fine and coarse sand
6
Subhas Sorovar
0- 56 clay
60
below 56 find and coarse sand
7
8
Bagmari park
Manicktala
0-40 m clay
Baksara
0-32 clay
45
Below 40 fine and coarse sand
35
below 32 fine and coarse sand
9
Tikiapara
0-48 clay
50
below 48 fine and coarse sand
10
Sovabazar
0- 56 clay
below 56 sand
60
Where to divert the rainwater in South Kolkata 2
Sl
No.
Location
Sub surface geology in meters
below ground level (mbgl)
Depth of the recharge well in mbgl
1
Alipur
0-24 clay
25
below 24 fine and coarse sand
2
3
4
Lansdown
Road
0-48 clay
Mandivilla
Garden
0-56 m
Barisha
0-40 clay
50
below 48 coarse sand
below 56 coarse sand
45
40 – 120 sand
below 120 clay
5
K P Roy
Road
0-8 clay
8- 48 fine sand
Shallow structures to depth of 15m and
deeper structure to a depth of 60m
48 – 56 clay
below 56 coarse sand
6
Ashok Nagar
0- 32 fine sand
32 - 72 clay
Shallow structures upto a depth of 15m
and deeper structures to a depth of 75m
below 72 fine and coarse sand
7
Jadavpur
0-16 clay
16- 32 fine sand
Shallow structures to depth of 20m and
deeper structures to a depth of 40
32 – 36 clay
below 36 fine and coarse sand
8
Dhakuria
0-16 clay
16-40 fine sand
Shallow structures at 20m and deeper
structures for a depth of 40m
below 40 coarse sand
9
Jodhpur Park
0-48 clay
Deeper structures upto a depth of 50m
below 48 coarse sand
10
Tiljaya
0-32 clay
35m
below 32 m coarse sand
Case studies
I.
Bidhan nagar Government College, Salt Lake.
Case Background
The college, which is of 7.5 acres (30,000 sq m), is located in Salt Lake. The daily water requirement is
fulfilled by municipal supply and from its own tubewell.
Measures taken for rainwater harvesting
Part of the rooftop rainwater is diverted to
storage tank of 12,000 litres capacity (see site
plan).
The approximate cost for constructing the
ferrocement tank was about Rs 30,000. The
project was implemented in January 2004 and
West Bengal Pollution Control Board funded
the project.
Rooftop rainwater harvesting
I. Storing rainwater
The rainwater generated at a rooftop area of
about 50 sqm from a total rooftop area of
2,000 sqm is harvested. The rooftop rainwater flow to the storage tank through the down takes pipe of 6-inch
diameter. The filtering tank provided in the top of the storage tank filters the silt from the rooftop. The stored
water is utilised for non-potable purposes like gardening and washing purposes. The cross section view of the
storage tank is given below.
II.
All India Soil and Land Use Survey ( AISLUS), Patuli- Baishanabghata.
Case Background
This is the first rainwater harvesting project of Kolkata at AISLUS complex. The project was funded by
CGWB, designed and implemented by Ardem Centre for Resource Development and Environmental
Management. The annual water harvesting potential of the site is about 811 cubic meters.
Rainwater harvesting measures
The rooftop rainwater from an area of 676 sq m is harvested
through recharge well with two recharge borewells.
The approximate cost for constructing the ferrocement tank was
about Rs 5 lakh. The project was implemented in 2004.
Rooftop rainwater harvesting
I. Recharging groundwater
The rainwater generated at a rooftop is collected in series of
collection chamber. The collection chambers are interconnected
by underground pipe and the water is finally diverted to the
recharge well (see picture of recharge well). The well is 11.57 m
in length, 1.65 m in width and 3 m in depth. The recharge well is provided with two recharge borewells of 150
mm diameter to a depth of 119 m. The recharge well is provided with gravel and sand for filtering purposes.
References:
1. Wetlands of Kolkata (Source: Kolkata – The city of wetlands, Dept of Fisheries, Govt of W Bengal)
2. Groundwater in urban environment of India, CGWB, Faridabad, Dec 2000.
3. Annual survey of Environment, Vasundhara, 2004
4. Annual survey of Environment, Vasundhara, 2003
5. Dhrubanjoti Ghosh, Institute of wetland management and ecological Design.
6. Nisitendra Nath Som, Director, Physical planning Unit, KMDA
7. Kolkata Municipal Corporation
8. Annual reports 2001-2002, West Bengal Pollution Control Board.
9. Better Business Bureau, Kolkata.
10. Water of west Bengal: Souvenir
11. The city of wetlands- Edited by Madhumita Mukherjee , Department of Fisheries, Govt of West Bengal.