The Association for People with Disability (APD) instituted water conservation measures, the details of which are in this document. A video of the project can be seen at https://www.youtube.com/watch?v=KvaYBzTPAPc

1. RAINWATER HARVESTING & GROUNDWATER RECHARGE
PROJECT AT APD, BENGALURU
1.0 Introduction
The Association for People with Disability (APD) is located on Doddagubbi Road in Kothanur.
APD is an NGO that has been transforming the lives of underprivileged people with disability
since 1959. They run extensive programs in rural and urban Karnataka to enable, equip and
empower children and adults with various disability issues. While they have multiple focus
areas, one of them is horticulture training, for which they have a campus in Kothanur.
The campus is set on a plot of 5 acres with residential accommodation for about 140 students
staying in the hostel. There are around 10 buildings, including a hostel, dining room/kitchen,
classrooms, etc, spread across the campus. There are about 40 staff and other workers during
the daytime. APD is a green space with several trees and extensive garden areas.
APD does not receive piped water supply from the Bengaluru Water Supply and Sewerage
Board (BWSSB) and is dependent on in-house borewells and water tankers. In order to
increase the borewell yield, the management decided to implement rainwater harvesting
and groundwater recharge. APD approached Biome Environmental Solutions for knowledge
https:/
/biomewatermanagement.in | http:/
/biometrust.org | http:/
/bengaluru.urbanwaters.in
1

2. assistance. Every drop of rainwater is harvested on the campus, as much as possible. As a
result, the borewell yield has increased, and the dependence on water tankers reduced.
Map of APD (left) and the campus (right)
2.0 Water Management
2.1 Water Demand:
The total water demand is around 28 kilolitres (KL) per day. Out of this, 21 KL is used for
domestic and flushing needs and around 7 KL litres is used for nursery/gardening. The
per-person water consumption is around 150 litres.
Water source Daily consumption (KL) Monthly consumption (KL) Annual consumption (ML)
Borewell 3.5 105 1260
Tankers 245 735 8820
Total 280 840 10080
*For reference:
L - litres; KL - kilolitres; KLD - kilolitres per day; ML - megalitres (million litres); OWC: Organic waste collector
2.2 Water Supply:
Piped water - APD does not have BWSSB’s piped water supply. It is dependent on in-house
borewells and tanker water.
2

3. Borewells - The campus has 5 borewells, of which only one is being used on a regular basis
currently. The water is pumped 4-5 times a day for 15-20 minutes each time. The details of
each of the borewells are listed below:
Borewells Year of drilling Depth
BW 1 2000 450
BW 2 2002-03 500
BW 3 2002-04 400
BW 4 2003-04 400
BW 5 2010-12 600
The yields of the wells are currently not available
Water Tankers - The in-house borewells fail to meet the required water demand, and the bulk
of the water needs are met through water tankers. Around 3 or 4 tankers of 7 KL are bought
every day. APD spends around Rs 4 lakhs annually on water tankers.
2.3 Water storage infrastructure:
Storage structures Location Capacity (in KL)
Underground sump tanks Adjacent to the hostel block 25
Main overhead tank 25
Sintex overhead tank Hostel block 8
Sintex overhead tank Canteen block 2
2 smaller Sintex tanks 1 each on the smaller toilet
block and OWC block
Not known
Total 60
2.4 Treatment infrastructure:
● Water Treatment - There is no Water Treatment Plant in APD. The drinking water
requirement is met by buying 25 cans of 20 litres each, which comes to 500 litres daily.
● Sewage Treatment Plant (STP) - There is an STP with DEWATS technology of 25 KLD
capacity set up in 2009. It was not used for the past 8 years and has been revived now.
Though the STP is functional, the output water from the STP is still let out since there
3

4. is a lot of silt and chemical contamination. Only a part of the treated wastewater
(TWW) is being used for plantation crops like trees and coconuts, and most of it is
being let out of the campus.
3.0 Implementing rainwater harvesting through Biome
In January 2020, APD got in touch with Biome Environmental Solutions to evaluate and
suggest ways to improve the existing rainwater harvesting system and recommend
measures for water sustainability at the campus. Biome studied the water situation of APD
thoroughly and recommended the following initiatives:
3.1 Rooftop rainwater harvesting
The average rainfall that Bengaluru receives has been recorded as 970-975 mm, with the
average number of rainy days as 60. The total rain that falls on an area is called the ‘rainfall
endowment’ of that area. Not all of this rain can be harvested or is visible as runoff. The
percentage of runoff depends on the surface on which the rain falls. The greater the
percentage of paved/built-up area, the more the runoff – this can be up to 90% of the rainfall
endowment. For a total site area of 20288 sqm, the APD campus has a rainfall endowment of
19,771 KL (~20 ML) annually.
The runoffs from the various surfaces - building rooftops, paved areas and landscaped areas -
for annual rainfall, moderate rain (30 mm) and heavy rain (60 mm) are given in the table
below. This is calculated by multiplying the catchment area (a), the percentage of water that
can be harvested off it (b) and the rainfall in mm (c): a*b*c
Type of catchment Area
(sqm)
‘a’
Runoff
coefficient
‘b’
Annual
runoff at
974.5 mm
rain (KL)
‘c’
Runoff
at 30
mm rain
(KL)
‘c’
Runoff at
60 mm
rain (KL)
‘c’
Contribution
to total
runoff (%)
Terrace area (hostel) 554 0.9 486 15 30 7%
Terrace area
(canteen)
250 0.9 219 7 14 3%
Terrace area (OWC) 92 0.9 81 2 5 1%
Terrace area (toilet) 38 0.9 33 1 2 0%
Total terrace area 934 0.9 819 25 50 11%
Paved areas (tar
road and other
paved areas)
2138 0.7 1458 45 90 20%
Landscaped area 16978 0.3 4964 153 306 69%
Total of paved and 19116 6422 198 395 89%
4

5. landscaped areas
Total 20050 7241 223 446 100%
Rainfall runoff from various surfaces
● From this table, it can be seen that the maximum runoff is from the landscaped area.
Rooftop runoff contribution to the total runoff is 11%, the paved area runoff contributes
20%, and landscaped area runoff is 69%.
● The annual water demand of the campus is 10080 KL. The annual rooftop runoff of 819
KL can meet 8% of the total annual water demand of the campus, provided the rainfall
is normal and adequate storage is provided.
3.2 Existing rainwater harvesting system
● The rooftop runoff from all the buildings is let out onto the surface of the ground.
● The paved and landscaped area runoff gets recharged at the pond and other low-lying
areas, and the overflow water drains out into the nala on the south side of the
property where a NIMHANS campus is coming up.
3.3 Biome’s recommendations
A. Rainwater harvesting
Biome Environmental Solutions, after calculating the rainwater harvesting potential of the
campus and in adherence to BWSSB’s new bylaws, recommended harvesting the rooftop
rainwater from the hostel, canteen, OWC and toilet buildings. Rooftop rainwater from the
hostel and canteen buildings is stored in a tank of 5000 L and is pumped to the main tank
from there for use. Rooftop rainwater from the OWC and toilet buildings is stored in a rain
barrel of 500 L after passing through a simple perforated plastic bowl filter with jelly stones.
The water is used in the toilets.
5

6. Hostel block Canteen block
OWC block Toilet block
Perforated plastic bowl filter
6

7. B. Groundwater recharge:
Based on BWSSB’s amended bylaws, Biome suggested digging 16 recharge wells (RW) which
could recharge 233 KL of water (from 30 mm rainfall) from all the paved and landscaped
areas. While digging, four RWs hit rock at less than 10 ft, and to accommodate the runoff
from neighbouring properties in heavy rain, additional recharge wells were suggested. A total
of 25 recharge wells were dug by well-digger Ramakrishna and his team.
Recharge wells executed at APD campus
Recharge well
Diameter
(feet) Depth
Static volume
(KL) No of wells Total volume (KL)
RW1 to RW8 3 20 4 8 32
RW9 to 10 4 25 9 2 18
RW11 to RW14 5 30 17 4 67
RW15 to RW17 5 8 4 3 13
RW18 5 13 7 1 7
RW19 to RW21 3 33 7 3 20
RW22 4 25 9 1 9
RW23 4 28 10 1 10
RW24 5 22 12 1 12
RW25 5 24 13 1 13
Total 25 201
7

8. The schematic diagram below shows the proposed buildings for rooftop rainwater harvesting
and recharge well locations at APD.
8

9. Recharge wells
4.0 The impact
Every single drop of rainwater is stored and used or recharged on the campus. This has
resulted in increasing the yield of the functional borewell.
● Before implementation, the borewell was in use for 1 hour every day. After digging the
recharge wells, it can be pumped continuously for 3 hours.
● The dependence on water tankers has been reduced from 3-4 tankers to 1 tanker per
day.
● APD is able to save Rs 3 lakhs annually on the cost of water tankers.
“APD horticulture campus has 5 acres. Our groundwater is insufficient to sustain the
greenery. We have 3 borewells, but only one borewell has a little water. Our management
decided to dig recharge wells to increase the groundwater level. One observation is that
previously our borewell was in use for only 1 hour. Now, we pump for 3 hours continuously
from our borewell. Most of the rainwater wasted earlier is now being stored in a recharge
well.”
Yashoda, Senior Manager, APD
9

10. 5.0 Biome’s recommendations for the future
1. During the good rainfall in 2021, all the recharge wells held rainwater. In the future, if
the recharge wells continue to hold rainwater, the water could be pumped out and
used for gardening and domestic purposes.
2. The yield of the other 4 borewells should be evaluated, and they could be put back
into use if they hold water.
3. Installing aerators on all taps will contribute to reducing water use on the campus.
4. Installing signage - naming the borewells and recharge wells will identify their
locations, contribute to ease of maintenance and encourage the campus community
to be aware of, understand and take ownership of their water management practices.
5. Installing a rain gauge to capture rainfall data will help in planning horticultural
activities.
6. The recharge wells will need to be de-silted once in five years, at least.
7. The sludge from the STP could be used as fertiliser in the gardens and fields after
treatment.
8. Establish a sludge treatment facility within your campus to treat the sludge when the
DEWATS is de-sludged. The treated sludge can be used as soil conditioner for
horticulture needs on the campus.
Note: Future plans include the use of treated wastewater for gardening
Contact: water@biome-solutions.com
10