Urban water scenario
Even though the rate of urbanisation in India is among the lowest
in the world, the nation has more than 250 million city-dwellers.
Experts predict that this number will rise even further, and
by 2020, about 50 per cent of India's population will be living
in cities. This is going to put further pressure on the already
strained centralised water supply systems of urban areas.
The urban water supply and sanitation sector in the country
is suffering from inadequate levels of service, an increasing
demand-supply gap, poor sanitary conditions and deteriorating
financial and technical performance.
What a stress?
According to Central Public Health Engineering Organisation
(CPHEEO) estimates, as on 31 March 2000, 88 per cent of urban
population has access to a potable water supply. But this
supply is highly erratic and unreliable. Transmission and
distribution networks are old and poorly maintained, and generally
of a poor quality. Consequently physical losses are typically
high, ranging from 25 to over 50 per cent. Low pressures and
intermittent supplies allow back siphoning, which results
in contamination of water in the distribution network. Water
is typically available for only 2-8 hours a day in most Indian
cities. The situation is even worse in summer when water is
available only for a few minutes, sometimes not at all.
According to a World Bank study, of the 27 Asian cities with
populations of over 1,000,000, Chennai and Delhi are ranked
as the worst performing metropolitan cities in terms of hours
of water availability per day, while Mumbai is ranked as second
worst performer and Calcutta fourth worst (Source: Background
Paper - International Conference on New Perspectives on Water
for Urban & Rural India - 18-19 September, 2001, New Delhi.)
In most cities, centralised water supply systems depend on
surface water sources like rivers and lakes. Chennai, for
instance, has to bring in water from a distance of 200 km
whereas Bangalore gets its water from the Cauvery river, which
is 95 km away. Where surface water sources fail to meet the
rising demand, groundwater reserves are being tapped, often
to unsustainable levels.
The nation's capital is perpetually in the grip of a water crisis,
more so during the dry season, when the situation gets particularly
worse. As the demand-supply gap widens, more groundwater is
being exploited. Of the water supplied by the municipality,
approximately 11 per cent comes from groundwater reserves and
remaining from the Yamuna river. It is, however, difficult to
establish the total quantity of groundwater extracted because
a large number of tubewells (owned by individuals, industries
and bottled water companies) remain unregistered.
In Delhi approximately 13 per cent (Source:
Zerah., M Helene, 2000, Water - Unreliable Supply in Delhi,
French Research Institute of India) households do not receive
water every day and in Rajkot, Gujarat, water availability
in April 2000 was only for 30 minutes every alternate day.
The main sources of public water supply in the city are the
three reservoirs - Poondi, Redhills and Cholavaram - with an
aggregate storage capacity of 175 MCM. Even when the reservoirs
are not full, they get inflows from intermittent rains, which
is then drawn. On the other hand, losses due to evaporation
from the reservoirs result in the effective availability being
lower than the storage.
The other major resource is groundwater from the well fields
in the Araniar-Kortaliyar basin and the southern coastal aquifer,
and a large number of wells and tubewells spread all across
Over-extraction of groundwater in the north western coastal
belt resulted in a rapid ingress of seawater, which extended
from 3 km inshore in 1969 to 7 km in 1983 and 9 km in 1987.
Groundwater levels within the city also fell and brackish
water began to appear even in localities which earlier had
good quality groundwater sources.
With a population of 5,686,000, Bangalore is India's fifth largest
city. As per the estimates of the Bangalore Water Supply and
Sewerage Board (BWSSB), the total demand of water is 840 million
litres per day (MLD) (assuming a population of 6 million and
a supply rate of 140 litres per capita per day [lpcd]). (The
demand works out to be 1200 MLD, at the standard rate of 200
lpcd set by the Bureau of Indian Standards [BIS] for water supply
in urban areas). Corresponding demand supply gaps are 135 and
SOURCES OF WATER:
2. A conceptual frame for rainwater harvesting in Bangalore,
3. Vishwanath. S, 2000, Personal Communication
To meet the demand supply gap, the government has already
proposed to extract 770.0 MLD of water from the Cauvery river
under Cauvery stage IV project (Phase I and Phase II). The
production cost of this water per kilolitre is expected to
be Rs. 45.70. (On completion of these phases total extraction
from the Cauvery for Bangalore alone would be 1310 MLD i.e.
478 billion litres in a year or 16.78 thousand million cubic
Ground water extraction: According to a study conducted by
the Centre for Symbiosis of Technology, Environment and Management
(STEM), a Bangalore-based research group, the demand supply
gap is met by groundwater exploitation. It is estimated that
40 per cent of the population of Bangalore is dependent on