Sustainable
Water Supply Strategy for Bangalore - A model for emerging cities in India
Ammanaghatta Rudrappa Shivakumar *
KSCST, Indian Institute of Science, Bangalore, India.
rainmanskumar@gmail.com
Abstract:
Water supply for the city of Bangalore in India is
always short against the total demand. Surface water is inadequate to meet the
demand and the city has to depend on groundwater. Due to rapid urbanization,
infiltration of rainwater into the subsoil has decreased drastically and
recharging of groundwater has diminished. This scenario requires an alternative
source to bridge the gap between demand and supply. Rainwater, which is
easily available and is the purest form of water, would be an immediate source
to augment the existing water supply by “catching water wherever it
falls”. Recycling or reuse of treated water is another source for at least
secondary purposes. Karnataka State Council for Science and Technology (KSCST)
is actively participating in the socially relevant, environment friendly water
conservation measures and has been providing cost effective solutions since its
inception 1975. Rainwater Harvesting (RWH) Cell at KSCST is established to
study the needs of the people and provide sustainable and simple solutions
through innovation and implementation pertinent to Rainwater Harvesting and
Ground water recharge. Since November 2005 RWH Cell has provided technical
support for planning rainwater harvesting systems in over 300 institutions
(Public and private sector, Multinationals and Educational Institutions) in
Karnataka and other states of India. Several thousand visitors have personally
visited KSCST and availed the benefit and technical knowledge on RWH, water
conservation and ground water recharge. RWH cell established at KSCST is
providing policy support to the Government departments for water conservation
and rainwater harvesting programmes in Karnataka and other states in India. RWH App is developed with the support
of UNESCO by KSCST for web and Mobile users. Blog "RainManSpeaks from
Bengaluru" is in the web since April 1st 2014 and has published 81
posts. Quiz and Debate programs are organised to build awareness on rainwater
harvesting and water conservation measures among students and faculty of
schools and colleges.
Case
Study 1
'Sourabha'
Ecofriendly home of Bangalore in India is on a plot area of 2400 Sq.ft. This
house is entirely dependent on harvested rainwater for all its need including drinking
since 1994.
Case
Study 2
The strategy
for sustainable water supply plan for a city like Bangalore should have the
combination of conventional river water supply augmented by the 'New Water'
supply sources - a. Rainwater harvesting, b. Ground water recharge with
sustainable withdrawal and c. Reuse of waste water through treatment.
Keywords:
Rainwater
harvesting, Sustainable water supply, Water supply strategy to Bangalore,
Recharging of groundwater, Sourabha ecofriendly home, Rainwater harvesting
cell, RWH app, RWH Advisor.
1. Introduction:
Water supply for the city of Bangalore in India is
always short against the total demand. Surface water is inadequate to meet the
demand and the city has to depend on groundwater. Due to rapid urbanization,
infiltration of rainwater into the subsoil has decreased drastically and
recharging of groundwater has diminished. This scenario requires an alternative
source to bridge the gap between demand and supply. Rainwater, which is
easily available and is the purest form of water, would be an immediate source
to augment the existing water supply by “catching water wherever it falls” [1].
Recycling or reuse of treated water is another source for at least secondary
purposes.
Rainwater Harvesting (Figure 1) has emerged as a
viable alternative to traditional perennial sources of water in urban areas
facing water shortage and flooding during monsoons.
The estimated population of Bangalore Bruhath Bangalore Maha Nagara
Palikey's (BBMP's) 198 wards as per the 2011 census is 84.74 lakhs (8.474
million), up from 45.92 lakh in 2001. The population of men and women is 44
lakh and 40 lakh respectively. Since the population is below 1 crore (10
million), Bangalore remains a B class city [2].
The population density in Bangalore has
risen 47% in the past decade as job opportunities and economic growth have
attracted people to Bangalore. The number of people living per square
kilometer in the city has increased to 4,378 in 2011 from 2,985 in 2001.
Seven neighboring city municipal councils, a municipal
town and 110 villages were merged into Bangalore in 2007.
Bangalore is now
expanded to 800 sq km in its area. Bangalore Water Supply and Sewerage Board (BWSSB)
is planning to cover the BBMP area of 800 sq km. BWSSB has 8, 94,393 (Nov 2016)
connections for delivery of water which encompasses domestic, institutional,
commercial Government and others.
 |
| Figure 1. |
Realized the
importance of harvesting rainwater and as a first step through BWSSB, RWH has
been made mandatory for most of the properties in Bangalore since Nov 2009.
2.
Methodology:
Karnataka
State Council for Science and Technology (KSCST) is actively participating in
the socially relevant, environment friendly water conservation measures and has
been providing cost effective solutions since its inception 1975. Rainwater
Harvesting (RWH) Cell at KSCST is established to study the needs of the people
and provide sustainable and simple solutions through innovation and
implementation pertinent to Rainwater Harvesting and Ground water recharge.
Since November 2005 RWH Cell has provided technical support for planning
rainwater harvesting systems in over 300 institutions (Public and private
sector, Multinationals and Educational Institutions) in Karnataka and other
states of India. Several thousand visitors have personally visited KSCST and
availed the benefit and technical knowledge on RWH, water conservation and
ground water recharge [3].
RWH cell established at KSCST is providing policy
support to the Government departments for water conservation and rainwater
harvesting programmes in Karnataka and other states in India (Figure 2). The
guidelines established by RWH Cell are instrumental in pursuing State
Government to amend several acts and issue guidelines for mandatory
installation of RWH structures in all the government buildings, public parks,
roads and open spaces. Bangalore Water Supply and Sewerage Board (BWSSB) has
collaborated with RWH Cell of KSCST and brought in the legislation to
compulsorily install RWH system in certain category of properties in Bengaluru.
 |
| Figure 2. |
2.1. Training programme:
Skill development programme to train Architects,
Engineers and Plumbing contractors for hands on training and rainwater
harvesting project planning are being conducted every month. Since inception 74
training programmes are conducted till date and around 1,800 trained personals
are offering their services. The list of these trained personals with contact
details is available in the web link http://www.kscst.iisc.ernet.in/rwh_files/rwh_contractors.html
2.2. Web and Mobile phone app:
RWH App is developed with the support of UNESCO by
KSCST for web and Mobile users. Software Application "Do it Yourself RWH
Tool - RWH Advisor" was launch on the occasion of World Water Day
celebrations at Water Festival 2016 on 22.03.2016 at Bharat Nivas, Auroville,
Pondicherry by UNESCO representatives. http://rwh-advisor.info
2.3. Blog and social media:
Blog "RainManSpeaks from Bengaluru" is in
the web since April 1st 2014 and has published 81 posts. The reach as of
February 2017 is over 52,000 and in over 20 countries. Blog is reposted on
Facebook, Tweeter, and Google+ etc. http://rainmanspeaks.blogspot.in
2.4. Outreach activities:
Quiz and Debate programs are organised to build
awareness on rainwater harvesting and water conservation measures among
students and faculty of schools and colleges. Over sixty five Quiz and Debate
programs were conducted in Schools and colleges between October, 2013 and
February, 2017 at sixty five Private and Government High Schools and Colleges
in Bengaluru. This program has benefited 15,000 students and around 300 school
teachers who participated in Quiz. The programmes were organised with the
cooperation of over 150 volunteers from Nisarga Mahila Samaja.
Several lectures and presentations are being delivered
to promote rainwater harvesting by the Council across the state, in addition to
news paper articles and television programs.
Technical support and interaction is being provided
through, email, web site information, facebook, blog and Do It Yourself
RWH web and android based app supported by UNESCO http://rwh-advisor.info
3.
Help
Desk and Support Network - Rainwater Harvesting, Ground Water Recharge and
Water Management Programme for Bangalore City
Government of Karnataka realized the importance of
harvesting rainwater and as a first step through BWSSB, RWH has been made
mandatory for most of the properties in Bangalore effective from November 2009
[3].
3.1.
KSCST with the support of BWSSB has
established RWH Helpdesk at KSCST in Indian Institute of Science campus and
also at Rainwater Harvesting theme park in Jayanagar Bangalore. This 1.5 acre
park on 40th Cross in Jayanagar V Block, demonstrates all techniques of
harvesting rainwater. It has 26 working models on rainwater harvesting, ground
water recharge and water conservation. The Theme park established by KSCST is
the first of its kind in the country, to address frequently asked questions on
rainwater harvesting, water collecting systems, filtration and storage systems
and groundwater recharge methods.
3.2.
The helpdesk primarily aims at training
the stake holders such as architects, engineers, contractors, plumbers, masons,
etc within Bangalore city through several Training Programmes. Awareness Camps
are arranged to bring in awareness among the general public regarding Rainwater
Harvesting. Information on technical details of RWH and ground water recharge
are being provided at RWH helpdesk for those who visit KSCST or contact through
telephone, web and email.
3.3.
Skill development programme to train
Architects, Engineers and Plumbing contractors for hands on training and
rainwater harvesting project planning are being conducted every month. Since
inception 74 training programmes are conducted till date and around 1,800
trained personals are offering their services.
3.4.
People seeking assistance regarding
Rainwater Harvesting (RWH) visit RWH helpdesk at KSCST regularly. Around 20,100
students and teachers from 331 schools and 2,850 students and lecturers from
109 colleges in and around Bengaluru visited Helpdesk at Sir M Visvesvaraiah
Rainwater Harvesting Theme Park, Jayanagar. Over 33,000 people have visited RWH
helpdesks at KSCST and RWH Themepark till date. They are given practical
demonstration with the working models and RWH system at KSCST office by the
helpdesk engineers. Feedback from the visitors to the Helpdesk are being
collected regularly and analysed for improving the effectiveness of the
programme.
3.5.
Phone-in queries regarding RWH are being
attended appropriately through the helpline numbers: 080 23341652, 080 23348848,
080 23348849 and 080 26653666 at Jayanagar. RWH Theme Park. Around 3000 queries
are answered by helpdesk engineers. Various types of questions are convincingly
answered. Citizens are also helped to get the contacts of respective plumbers
and contractors in their area who execute RWH works. Emails and web enquiries
are answered regularly.
3.6.
Print and electronic media (News papers,
TV, Radio etc.) presented several articles in concern with RWH and RWH Helpdesk
activities.
3.7.
RWH helpdesk at KSCST has emerged as one
stop solution and an effort of the Council to conserve water in the city of
Bangalore. Rainwater Harvesting is one of the prioritized projects of KSCST and
an important measure to mitigate water scarcity and augment existing water
supply.
4.
Case
Study 1 - Sourabha Ecofriendly home of Bangalore in India [4]
Sourabha (Figure 3) is located in
southwestern part of Bangalore
Rainwater falling inside the plot is
being channeled to three applications.
- Roof
top rainwater harvesting
- Roof
top rainwater channeled to recharge ground water
- Percolation
in garden area to recharge ground water.
Majority of the rainwater falling on the
roof (85%) is channeled to the northern side of the house and is allowed flow
in to a tank of 4500 lts. capacity built on the ground floor roof. PopUp filter
along with a stabilization tank specially designed will filter the roof water
before storing. This water is used during the rainy season. The over flow of
this tank is allowed to rundown through rainwater pipe on the wall to an underground
sump-1 of 25,000 lt capacity built under the portico at the entrance of the
house. In the event of these two tanks getting full, the rainwater is diverted
to percolate into the ground through a system of percolation tanks /
infiltration gallery (4 recycled plastic drums interconnected and buried
underground with their bottom cut open) to recharge ground water.
The remaining portion of the roof water
(15%) is allowed to rundown through rainwater pipe on the wall and a PopUp
filter installed at the ground level filters suspended and floating material.
Relatively cleaner water after filtration flows to an underground sump-2 of
10,000 lt Capacity built inside the car park (garage). Sump-1 and sump-2 together with 35,000 lt
capacity are interconnected and the stored rainwater water is used during the
non rainy days when the roof top tank water is not available.
 |
| Figure 3. |
Rainwater falling in the open area or
the garden area around the house is allowed to percolate then and there in to
the ground to recharge ground water.
In this manner not a drop of rainwater
falling in the plot is allowed to flow out.
Bangalore receives around 1000mm of
rainfall in a year. Which translates in to around 2, 23,000 lts per year
cumulatively in a plot of 60 ft. X 40 ft. Bangalore
There is no Corporation or BWSSB water
connection to this house. Clean and safe water is available 24 hours 365 days a
year and the quality of water is also periodically tested and found to be good.
‘Sourabha’ house has inbuilt simple
mechanisms to effectively harness all the rainwater falling in the plot and
channel the same for different purposes. Even before constructing the house,
rainwater harvesting was the answer for the water requirement. The house was
constructed by using the harvested rainwater. Since 1995 the entire house needs
including potable water is met out of rainwater. As a family of four, water
required per month is around 15,000 lts.
A family require around 400 lt per day
for all the needs except for toilet flushing and part of gardening. The need of
toilet flushing is met by recirculation of used water from laundry washing
machine. Used water from washing machine is stored in an underground tank and
is pumped up to a tank on the roof with vetiver
grass. The aerated washing machine discharge water is then used for toilet
flushing. Wash water from kitchen sink is diverted for gardening.
During days with more than 100 days of
continues no rainy days which is very rare in Bangalore
There is no recurring cost involved
except for the electricity used for pumping up water. The electricity
consumption in Sourabha is around 80kWh (units) per month, which includes water
pumping also. Low electricity consumption in the house is due to several energy
conservation methods and renewable energy techniques adopted in the house.
Green building standards achieved for
living in Sourabha:
- Water requirement of 400 lt per
day and only harvested rainwater used all through the year
- Electricity consumption of only
80 kWh per month
- LPG cylinder of 14 kg lasts for
around 90 days
- Only 2kg of dry rejects as
waste goes out of the house per week. All organic
waste converted and used as manure through vermicompost.
5. Case Study 2 - Sustainable
water supply plan for Bangalore:
Water supply to Bangalore
5.1.
Comprehensive
plan with rainwater harvesting as the new decentralized source:
Meteorological data reveals that the
rainfall in Bangalore Bangalore Bangalore
 |
| Figure 4. |
The precipitation in the open space of Bangalore
Cauvery water supply at the tap end in
Bangalore is 250,057 ML (685 MLD) Roof top rainwater Harvesting can provide 2,04,380
ML, Ground water available through RWH will be 1,85,800 ML and the facilities
of waste water treatment plants can provide 1,89,800 ML Totaling to 3,07,048 ML
or 841 MLD. The “New Water” available at consumer end from the three sources
(RWH, Ground water and Waste water treatment plants) will be 509 MLD which is almost
equal to the current water supply at the tap end Figure 5.
 |
| Figure 5. |
Table 1. [5] [6]
Bangalore Data
|
Units
|
Value
|
Urban Population (2011)
|
Million
|
84.6
|
City Roads (length)
|
km
|
1,500
|
Number of Properties
|
No.
|
20,00,000
|
Area
|
sq
km
|
800
|
Water supply 2015
|
MLD
|
1350
|
Water Demand 2015
|
MLD
|
1850
|
Short fall
|
MLD
|
500
|
Projection
|
||
Supply 2017
|
MLD
|
1470
|
Demand 2021
|
MLD
|
2100
|
Short fall
|
MLD
|
630
|
Cauvery water supply 2011
|
TMC
|
12.25
|
Cauvery water allotment
|
TMC
|
19
|
Rainfall in Bangalore (100 years
average)
|
mm
|
929
|
Rainy days in Bangalore per year
|
No.
|
57
|
Number of properties in Bangalore
- BMP
|
No.
|
20,00,000
|
Average roof area of a property
(estimate)
|
sq
m
|
110
|
Sump size in each property -
proposed
|
lt
|
5,000
|
Total water storage capacity in
Bangalore properties
|
lt
|
100000,00,000
|
ML
|
10,000
|
|
Urban population
|
No.
|
845,70,000
|
BBMP area
|
sq
km
|
800
|
sq
m
|
8000,00,000
|
|
Total water supply per day BWSSB
|
MLD
|
1,350
|
lt
|
13500,00,000
|
|
BWSSB transmission losses
|
%
|
49
|
Actual water supply per day
|
MLD
|
685
|
lt
|
6850,87,878
|
|
Recycled water available from
BWSSB (Tertiary Treatment)
|
MLD
|
520
|
Water requirement days
|
No.
|
365
|
Water unit
|
ML
|
10,00,000
|
Rainwater potential in BMP area
(annual)
|
ML
|
7,43,200
|
Water requirement of Bangalore -
BMP area (annual)
|
ML
|
4,92,750
|
Number of families in Bangalore
|
No.
|
169,14,000
|
Roof Top Rainwater Yield (Annual)
|
lt
|
2043800,00,000
|
ML
|
2,04,380
|
|
Roof Top Rainwater available @ 80%
effic (Annual)
|
ML
|
1,63,504
|
Roof Top Rainwater available -
days
|
No.
|
239
|
Rainwater Yield from BMP open area
(Annual)
|
lt
|
3901800,00,000
|
ML
|
3,90,180
|
|
Open Area Rainwater available -
days
|
No.
|
570
|
Total number of days rainwater
available per year
|
No.
|
808
|
Availability of Rainwater in
Bangalore to meet the demand
|
Months
|
26.9
|
Detergents used in each house per
month
|
kg
|
5
|
Detergents used in Bangalore per
day
|
kg
|
28,19,000
|
tone
|
2,819
|
|
Detergents used in Bangalore per
day
|
truck
loads
|
282
|
Per capita water availability
BWSSB
|
lt
|
16
|
Per capita water availability
BWSSB actual
|
lt
|
8
|
Table 2.
|
||
Strategy for Sustainable Water
Supply to Bangalore
|
100
|
1,018
|
%
|
MLD
|
|
Roof top rainwater
|
20
|
204
|
Ground water
|
20
|
204
|
Recycled water
|
10
|
102
|
Cauvery water
|
50
|
509
|
Table 3.
|
||
Water Requirement - How to meet?
|
ML
/ Yr
|
MLD
|
Total
|
2,50,057
|
685
|
Roof top rainwater available
|
2,04,380
|
560
|
Roof top rainwater required
|
74,281
|
204
|
Water required from ground water
recharge
|
74,281
|
204
|
Potential for ground water
recharge and withdraw
|
1,85,800
|
509
|
Recycled water for secondary water
use required
|
37,140
|
102
|
Recycled water for secondary water
use available
|
1,89,800
|
520
|
Cauvery water required
|
1,85,702
|
509
|
Cauvery water available
|
4,92,750
|
1,350
|
Excess Cauvery water available for
new areas in BBMP
|
3,07,048
|
841
|
Year
|
2015-2016
|
|
Water supplied
|
ML
|
2,50,057
|
Water received
|
ML
|
4,92,750
|
Unaccounted
|
ML
|
2,42,693
|
Accounted
|
%
|
51
|
Unaccounted
|
%
|
49
|
Number of Bore wells in Bangalore (conservative
estimate)
|
No.
|
4,00,000
|
Cost of each borewell
|
Rs.
|
1,00,000
|
Total investment on bore wells in
Bangalore
|
Million
Rs.
|
40,000
|
Investment on water storage sump
|
Rs.
per lt.
|
5
|
Total investment on water storage
sumps in Bangalore
|
Million
Rs.
|
50,000
|
MLD - Million Liter per Day
|
||
ML - Million Liter
|
||
lt - Liter
|
6. Conclusion:
The strategy for sustainable water supply plan for a
city like Bangalore should have the combination of conventional river water
supply augmented by the 'New Water' supply sources ( a. Rainwater harvesting, b.
Ground water recharge with sustainable withdrawal and c. Reuse of waste water
through treatment).
7. References:
[1]
'Amruthavarshini' A Guide for
Rainwater Harvesting, by A. R. Shivakumar
[2]
Task Force for Recovery of Public
Land and Its Protection Bangalore June 2011, By V. Balasubramanian IAS (Ret.)
[3]
Karnataka State
Council for Science and Technology web site, http://www.kscst.iisc.ernet.in/rwh.html
[4]
Rain Dance on the Roof Top - Water
Energy Environment for a sustainable living, By A. R. Shivakumar
[5]
Bangalore Water Supply and Sewerage
Board (BWSSB), Annual report 2014-15
[6]
Bangalore Water Problems of the Fast
Growing City of India, Editor Subhajyoti Das 2011
8.
Abbreviations:
Rainwater
Harvesting (RWH)
Karnataka
State Council for Science and Technology (KSCST)
Bangalore
Bruhath Bangalore Maha Nagara Palikey's (BBMP's)
Bangalore Water Supply
and Sewerage Board (BWSSB)
Kilometre - km
Million Liter - ML
Million Liter per Day
- MLD
Thousand Million Cubic
Feet - TMC ft
Mille Metre - mm
* A. R. Shivakumar, Principal Scientific Officer,
Karnataka State Council for Science and Technology, Indian Institute of
Science, Bangalore - 560 012.
