Detailed case study of rainwater harvesting for storage and recharge at Sonnappanahalli Govt Higher Primary School.

1. Rainwater Harvesting at Government Higher Primary
School, Sonnappanahalli
Biome Environmental Trust,
264, 6th Main Road, BEL Layout
6th Block, BEL Layout, Vidyaranyapura,
Bengaluru, Karnataka 560097
www.biometrust.org
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2. 1.0 Basic information about the school
Name of school Government Higher Primary School, Sonnappanahalli
Contact information Mr Venkate Gowda (Headmaster)
Number of students 360
Classes 1st - 8th std
Number of faculty 12 teachers, 6 non-teaching staff
Sonnappanahalli Govt Higher Primary School is a co-educational Kannada medium
school with classes from the first to the eighth standard. It has seven buildings, of
which two are new, and have 2 floors (G + 1). There are two toilet blocks and a
playground. There are two handwash stations, one near the staff room, and the
other has been converted into a drinking water station. There is also an Anganwadi
on the same campus, for which two more new buildings have been built.
Google map view of the school
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3. 2.0 Water situation in the school before intervention
The school receives water from the panchayat borewell 3 - 4 times a week, through a
pipe connected to the borewell. The daily water demand is 5000 litres, for
handwashing, washing plates and the toilets. Drinking water is obtained from two
RO plants installed on the school premises by DrinkPrime. The daily water demand
works out to 13.2 lpcd, which is much below the BIS 1993 standards of 45 lpcd.
The school has two old sump tanks near the entrance - each of 28300 litres. One has
cracks and is not in use. The other is used as a backup. There are four overhead tanks
- one on one of the new buildings, one each on both the toilet blocks, and one on the
office building - near the functional handwash station. There is an open well with a
diameter of 16.5 feet and a depth of 35 feet, whose water was used for the toilets. It
fell to disuse later on and was not maintained.
Akshayapatra supplies midday meals for the schoolchildren. This had been paused
during the COVID pandemic when monthly rations were supplied instead.
In spite of the panchayat overhead tank (50 KL) being on the school campus, both
the school and the Anganwadi faced a shortage of water due to inadequate supply
from the panchayat borewell.
Layout of the school campus
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4. New buildings Toilet blocks
Open well to be rejuvenated
3.0 Plan for intervention
Puravankara Ltd provided funding for the installation of a rooftop rainwater
harvesting system at the school. The implementation was done by Biome
Environmental Trust in Feb - Mar 2022. ITC’s Mission Sunehra Kal supported the visits,
water literacy sessions at the school and setting up of the Water Quality Learning
Centre. They also funded the construction of the handwash station and the rainwater
harvesting system at the Anganwadi.
4.0 RWH system implementation details
The implementation of the rooftop rainwater harvesting system was done on the
two new buildings that had downtake pipes from their terraces - the primary and
higher primary blocks and two old buildings housing the Anganwadi. A new sump
tank was constructed, into which the rooftop rainwater from the two new buildings
was channelled after being passed through a custom-built masonry filter.
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5. Rainwater harvesting potential of the school
The rainwater harvesting potential of the school was calculated by taking into
account only the rooftops of the two new buildings. The older buildings were not
considered, as their roofs were not clean.
Catchment
Roof area
(sft)
Roof area
(sqm)
Runoff
coefficient
Runoff in
30 mm rain
(litres)
Runoff in
60 mm
rain
(litres)
Runoff in
annual
rainfall 974.5
mm (litres)
Building 01 1464 136 0.9 3672 7344 119287
Building 02 1090 101 0.9 2734 5468 88813
Total 2554 237 6406 12813 208100
Table showing RWH potential calculation
The dimensions of the new sump tank are length 10 ft, width 6 ft and depth 7 ft, with
a volume of 420 cuft or around 12000 litres (12 KL). The custom-built masonry filter is
3 ft x 3 ft x 3 ft in size, with a capacity of around 765 litres. The harvested rainwater is
used in the toilets, for washing hands and plates, cleaning and watering the garden.
The overflow from the sump tank is directed into an existing recharge well of 4 ft
diameter and 15 ft depth. Another recharge well of the same size near the compound
wall receives surface runoff. Both have been funded by Athaang Devanahalli Tollways
Pvt Ltd. The first well is also used as a source of water - which is pumped into the
sump tank and used for all non-potable purposes.
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6. Design diagrams showing the RWH system components
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7. First rain separator (FRS) Masonry filter
Sump tank construction
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8. Rainwater harvesting system at the Anganwadi
There are two Anganwadi buildings occupied by 50 students. The roofs of these
buildings did not have parapets, and rainwater would flow down the walls. Parapets
were constructed, and downtake pipes were added. The combined roof area is 840
sft. The rooftop runoff is stored in an existing 10 KL sump tank. Annually, around 68
KL of rainwater is harvested, which meets around 68 days of water demand. The
installation of this system was done by Myrada with technical support from Biome
and funding from ITC MSK. The panchayat later installed a pump.
Anganwadi with RWH filter on the left
5.0 Other interventions
A normal tap has a flow rate of 15 litres per minute (L/min) when fully open. Flow
restrictors reduce the flow rate to 7 L/min. These were installed on nine taps in the
school’s handwash area. Aerators can further reduce the flow rate to 4 L/min. An
aerator was installed on one tap in the handwash area. The handwash area has been
enclosed by a grill that can be locked, in order to prevent pilferage and vandalism.
Flow restrictor Aerator
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9. Handwash area grill enclosure
A Water Quality Learning Centre has been set up in the school. The teachers and
students have been trained in water quality testing, and test kits have been given to
the school, to help keep track of the quality of the water used at the school.
ITC MSK has also funded the painting of the walls and rainwater filters with
information about the RWH system and its maintenance.
Wall painting on the school and anganwadi
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10. The school’s open well is awaiting cleaning. The well water is currently being used to
water the school garden.
The Embassy Group has adopted the school and funds regular maintenance activities
for which two people have been employed. Embassy also provides cleaning materials
for the school, and funds the students’ school bags and books.
6.0 Performance of system and learnings
● Assessment of overall project performance against plan
The original plan was to do rooftop rainwater harvesting for 2 Anganwadi
buildings and 2 buildings of the Higher Primary school.
- Later, when Athaang Toll Plaza wanted to fund 2 recharge wells in the school,
they were convinced to do one recharge well with a of diameter 4 feet and a
depth of 15 feet near the rainwater sump to use the overflow from the sump
for groundwater recharge. The recharge well also holds water for a few
months during the rainy season, which has been pumped and used by the
school.
- Aerators for water demand management, water literacy sessions for the
students, teachers and SDMC members, a water quality learning centre in the
school for educational purposes, RO filters for drinking water, etc, which were
not part of the initial plan, were added later due to the interest shown by the
school staff towards utilising and maintaining the facilities provided.
● Participatory team assessment of project
The Anganwadi staff would request donors to fund tanker water purchase.
The water was stored in the sump tank, and was drawn water manually. They
were not getting any water from the panchayat, and were happy with the
installation of the RWH system and pump, which have made it much easier to
access water.
The HM of the GHPS, teachers, and students are using the system for water
literacy in the school. The students are actively involved in operating and
maintaining the system. When the recharge well started holding water, the
school started using the water and continued to do so even after the rains
stopped. Before aerators were installed, one senior student used to monitor
the water usage at the handwash station - now that is no longer needed.
● Description of project successes
This project has been used as a showcase project for training plumbers in
RWH on one occasion since it was completed. Different groups of people have
visited the school - students from a Swiss University, panchayat officials from
Hoskote, etc. The dedicated maintenance staff takes good care of the RWH
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11. system. ITC’s Parisara Habba was conducted at the school premises. It is
hoped that this project will have a multiplier effect in promoting the concept
of rooftop RWH in the area.
ITC’s Parisara Habba at the school
Visit by Swiss students Visit by German students
Visit by stakeholders from Hoskote
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12. ● Lessons learnt
The success of such systems depends on regular and proper maintenance. The
school has two full-time housekeeping staff who take care of the terrace
cleaning, filter cleaning, operation of the first rain separator valve, etc. The
HM of the school has also trained some of the students to regularly monitor
the RWH system. The learning has been that it is important for the
implementing NGO to follow up with the school once in a while and keep
reminding them about the maintenance of the RWH system to ensure that the
system is optimally utilised. It is worthwhile investing in a dedicated
maintenance team for this and other maintenance required in the school.
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