Bangalore Environment Trust Newsletter, August
Sat, 03/03/2007 - 19:59 — admin
INTRODUCTION: Bangalore has a major drinking water supply
problem. This is due to a combination of an exploding population
and the distance of any major perennial source of supply. Water
therefore has to come from the river Cauvery from a distance of
nearly a 100 kms. It has also to be pumped up 1600 ft because of
Sustainable water supply in a city's context is defined as being
able to ensure consumption demands from within the catchment area
and water basin within which the city is located. If water has to
be transported from another basin then it cannot be sustainable.
Options which are being explored to make water supply sustainable
include demand management through pricing, recycling of used water
after treatment, charging of ground water table through
percolation tanks and lakes etc.
ROOFTOP RAIN WATER HARVESTING: One significant option which
has not been extensively explored so far is that of rooftop rain
water harvesting. This paper seeks to look at the possibilities
and describes one such experiment in the Bangalore context.
Thanks to extensive data maintained on meteorological conditions
of Bangalore, information on rainfall data is available for over
more than 100 years. The mean annual rainfall for Bangalore is
859.60 mm received over 57 rainy days. This suggests a significant
quantum of rain and also speaks about a distributive spread.
Bangalore has three different rainy periods covering 8 months of
the year. June to September is the principal rainy season where
about 54% of the total annual rainfall is received with 34 rainy
days and a mean rainfall of 496 mm.
October to December is the North-East monsoon period with a mean
rainfall of 241 mm in about 14 rainy days.
In April-May the mean rainfall is 156 mm and the number of rainy
days is 10.
THE SYSTEM: A very simple system is adopted for rooftop
rainwater harvesting. The entire roof area is made to act as a
rain collector. The roof slopes towards rainwater down spouts
which have a wire mesh at their mouth as a grit and leaf
separator. Water from these rain water spouts is lead down to
ground level and made to pass through a box which has charcoal and
sand. This acts as a filter. The filtered water is then stored in
a sump of about 2000 litres capacity. As and when required, the
rain water so collected is pumped up into an overhead tank of
about 1000 litres capacity and used for all forms of domestic
OPTIONS: Collection of rain water can be done either at the
roof level itself, in ground level tanks or in underground sumps.
In Bangalore underground sumps are a common feature in every house
and therefore appear to be the best option to store rainwater.
Rainwater harvesting has the maximum efficiency and effectiveness
in single storeyed or double storeyed independent houses. The
system is best applied for new constructions as adequate planning
becomes possible in the design of the system. The costs of
collection and storage can also be easily merged in the
construction cost and no significant extra cost is entailed.
Retrofitting to already built houses is also possible if any owner
is so inclined to adopt the system.
COSTS INVOLVED: For a house under construction rainwater
pipes and sump is usually already included as part of the
construction. Additional cost involved for rainwater harvesting
would be in adding capacity to the sump. This would be about
Rs.4500/for a sump of 1500 litres capacity.
For a house to be retrofitted cost would be in the range of
Rs.4500/- for additional capacity to the sump and about Rs.1500/-
for additional pipes.
QUANTITY OF RAINWATER COLLECTION: In Bangalore, given .a mean
rainfall of 859.60 mm and assuming a loss of about 10% due to
evaporation and removal of dirty water during the first rain,
quantum of water that can be collected for different roof areas
As can be seen from the above table, a house with about 100 sq mt
roof area (approx. 10 squares of construction in local
terminology) would be able to collect 77400 litres of water.
For a family of 4 persons, with an average domestic consumption of
90 litres per person per day, About 215 days of water supply per
year can be available through rainwater harvesting alone.
PRECAUTIONS: some nominal precautions are called for during
rainwater harvesting including keeping the rooftop clean, free
from leaves, twigs, bird droppings etc; not drying clothes with
detergent laden water which may drip on to rooftop and mix with
rain water harvested; not strong insecticides, pesticides, glass,
oil etc which may mix with rainwater with harmful effects; not
washing the roof with soaps and detergents; keeping the sump
airtight and closed so as not to allow fly and mosquito breeding
CONCLUSION: Rooftop rain water harvesting offers a
possibility as a supplement to domestic water supply requirements
and in conjunction with adequate demand management systems such as
low volume flush, efficient taps and showers etc can considerably
reduce the burden on city level water supply networks.
The system is also economical, environment friendly and
individually manageable leading to self reliance. The option
should be effectively used especially by new house owners and
builders recognising that water is a finite resource which should
be judiciously and efficiently used.
We have personally used the system at our residence since about 2
years and are convinced about its advantages. For persons
interested, further details about rooftop rainwater harvesting can
be obtained from
264, VI Main, VI Block,
BEL Layout, Vidyaranyapura,
Bangalore - 560 097 Ph.8382435
A Case for Padestrian Rights in
Bangalore's Traffic Jungle
Pedestrian safety seems to be the least on the list priorities of
city's traffic planners and managers. The oversight is all the
more striking if one considers the fact that pedestrian -casualty
has been witnessing an alarming rise over the last few years in
Bangalore. It constitutes a sizable proportion of road accident
victims in general. According to one study, in the year 1994, 2200
pedestrians were seriously injured and 242 were killed in road
accidents. Also pedestrians seem to be the worst affected by
vehicular air pollution, especially f by the smoky exhausts from
heavy traffic vehicles, as they are present for a longer duration
on roads than others; any proposal to improve the conditions for
road safety and comfort has to incorporate measures to mitigate
vehicular air pollution. And, to make matters worse they are often
seen by other road users as a necessary evil! Exposed to the
poisonous fumes, abused by vehicle drivers, elbowed around for
lack of space - they exist as the silent suffering majority in the
With the exception of traffic infrastructure facilities,
everything in the city has been recording fast growth. Inadequate
urban public transportation system, pothole - humps filled roads,
steep rise in motorised vehicular traffic, poor implementation of
buildings bye-laws, are by and large the reasons usually discussed
in seminars and conferences with regard to traffic congestion and
air pollution. With no spokesperson to articulate their concerns,
pedestrians and cyclists are left to fend for themselves.
In this context, it is worthwhile to focus on two most fundamental
rights of pedestrians: Right to safety and Right to comfortable
walking on the roads. The enabling provisions that guarantee both
the rights are almost the same. Infrastructure problems do
contribute to pedestrian woes only to some extent. However, two of
the most simple but important issues that need urgent attention
are footpaths and pedestrian crossings.
On some roads, footpaths are missing - a case in point is Lavelle
road; While on others, they are either dilapidated or dying a slow
death, due to poor maintenance and various kinds of encroachments.
Uneven surface, existence of a wide variety of poles, pits,
junction boxes - all of these discourage pedestrians from using
footpaths, leaving them exposed to dangers. Encroachments by
hawkers, venders, vehicles and religious structures have reduced
the space for pedestrian movement on the footpaths. Clearing the
footpaths of encroachments is also a social problem. When it can
happen in Calcutta, why not in Bangalore? Political will is the
key. Hawkers and vendors need to be adequately rehabilitated and
strict rules must be enforced to see that no structures obstruct
Subways, footbridges and mini flyovers
At present facilities for pedestrian crossings are grossly
inadequate. As it is there are very few subways, footbridges /
flyovers, but even these are not fully utilised by pedestrians.
But for the presence of lathi wielding traffic cops, pedestrians
are never inclined to use these existing facilities. Some cases
in point are:
The subway and the pedestrian foot bridge that connect the
Bangalore Bus Stand and the City Railway Station; In front of
railway station, on Tank Bund road, it is a common sight to
observe men, women and children struggling to jump across the
five feet tall barricades to reach the railway station from
the bus stand side.
The mini flyover on Kempegowda Road appears like a ruined
monuments built by Kempegowda, the founder of Bangalore.
The subway near K. R. Market seems to be an extension of the
It is needless to say that we need iuerbridges and mini
flyovers at some selected points especially near hospitals and
schools. But pedestrians have to change their `short-cut'
behavior if they want to demand for more.
Zebra crossings at the junctions
At present most of the junctions have signals. However, for
pedestrians, its a test of patience as they have to wait for a
long time for the green signal. Having waited thus long, they
have to virtually run to reach the other side because the signal
time is too short. At some junctions where there are railing
barricades that separate the road and the footpath, the zebra
crossing becomes very crowded due to signal-junction box, signal
pole and so on. A case in point is Cauvery Emporium Junction on
M.G. Road - In fact, one end of the Zebra crossing was blocked
by barricades on one of the roads at the junction. The police
were quick to rectify when it was pointed out.
Other issues which need to be considered are
Creation of some pedestrian zones in market areas, where there
is a total ban on vehicular traffic.
Improving the trauma care facilities for accident victims.
Setting up Pedestrian Aid Posts at select locations to aid and
assist the foot-path commuter.
Last but the most important - education for behavior change
amongst all the road users including pedestrians. Ultimately the
responsibility for ensuring one's safety rests with one self,
which calls for a certain sense of discipline and change of
existing attitudes. Life is too precious to be lost on roads.
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