Case studies of 3 houses in Vidyaranyapura where rainwater harvesting has been implemented.

1. Rainwater harvesting best practices in Vidyaranyapura
Vidyaranyapura is located in the North of Bengaluru. It is surrounded by the
Doddabommadra, Narsipura, Singapura and Veerasagara lakes. The area started to urbanise
after the 1990s, and the lakes started to go dry. The lakes are now being taken up for
rejuvenation by the BBMP.
Vidyaranyapura is known for open wells. Before the formal piped water supply from the
BWSSB was rolled out, the households had to depend on groundwater alone. The majority
of the houses built during the late 1980s and 1990s dug an open well first and then used the
water from the well to build the house. The groundwater table there is less than 5 ft from
the ground level in many areas. Most of the wells in this area have been dug by well-digger
(late) Muniyappa and team (from Bhovipalya, Sarjapura).
There are many households that have implemented good water management practices like
rooftop rainwater harvesting and groundwater recharge. Here are the stories of three such
houses.
1. Rainwater harvesting at Raghuram Giridhar’s house
Mr Raghuram Giridhar is a resident of Vidyaranyapura in North Bengaluru. Eight members of
his family reside in the two-storeyed house, and the water demand is about 30,000 litres a
month. The household's water consumption is 125 LPCD (litres per person per day). Always
having been keen on sustainable water practices, Mr Raghuram Giridhar was aware of water
conservation practices such as rooftop rainwater harvesting and groundwater recharge. He
dug an open well, and the well water met the requirements for house construction. Here is
the story of rainwater harvesting in Mr Raghuram’s house, which has benefitted him greatly.
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2. Open well
Mr Raghuram started constructing his house in 2018. He chose not to drill a borewell to
meet the house construction and future water needs. He learnt that the groundwater table
in Vidyaranyapura is high and decided to dig an open well. He hit water at 8 ft and got 5
inches of water. Well-digger Shankar and team dug the well that was 18 ft deep and 3 ft in
diameter. The entire house was built using this water, and no additional sources of water
(water tankers) were used. Currently, the well has water at 5 ft from ground level. Mr
Raghuram has tested the water quality, which indicated that the well water was not
potable. He uses the open well water for all domestic purposes except for drinking and
bathing.
Raghuram Giridhar’s open well
Rainwater harvesting
Mr Raghuram implemented rooftop rainwater harvesting in 2020, where the rainwater from
the 1500 sqft roof passes through a rainwater filter and reaches a sump that is exclusively
used to store rainwater. The rainwater filter has a first rain separator (FRS), which provides
an outlet to bypass the first 1-2 mm of rain and prevent it from entering the sump. This
enables only water from a clean rooftop to enter the storage sump. The overflow from the
sump is directed to the open well. Mr Raghuram has also provided an overflow pipe to carry
excess rainwater from the open well into the stormwater drain.
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3. Rainwater storage sump (with rainwater filter)
The following table shows the rainwater harvesting potential of Raghuram’s house:
Type of
catchment
Area
(sqm)
Runoff
coefficient
Runoff generated at
30mm rainfall (in KL)
Annual runoff at 974.5mm
rainfall (in KL)
Rooftop area 139 0.9 3.8 121.8
Mr Raghuram can harvest ~122 KL of rooftop rainwater annually. He stores the rooftop
rainwater in a sump and uses the excess rainwater to recharge the open well.
Water storage infrastructure
Mr Raghuram has two water-storing sumps, one to store rainwater exclusively and the other
to store Cauvery water. He first constructed a water-storing sump of 11,000-litre capacity
before constructing the house, which is now used to store rainwater. He then constructed a
separate sump to store Cauvery water which is of 9,000-litre capacity. He pumps water from
the open well to an overhead tank (using a 1HP motor) of 1500 litres capacity.
Cauvery water
Mr Raghuram took a Cauvery water connection by paying Rs 75,000. Although he uses a lot
of the open well water (with recharge), his reliance on Cauvery water is minimal. The
household consumes about 15KL of Cauvery water every month and pays a monthly tariff of
Rs.200-300, including the sanitation cess of Rs.100.
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4. Challenges
A borewell was dug about 100 metres from Mr Giridhar’s house in March 2021. Due to this,
the open well water level came down by 10 feet, causing Mr Giridhar to get worried.
However, the well recovered to almost its original level in 15 days after one or two moderate
rains. This indicates the hydrogeological discontinuity between the open well and borewell
aquifers.
Production cost of water
Production cost of water is a method of arriving at the overall cost of different sources of
water per kilolitre. The following table shows the production cost of water for open wells,
borewells and Cauvery water.
Production cost of different sources Cost per KL (Rs)
Cauvery water without sanitation cess 32
Cauvery water with sanitation cess 38
Open well water 7
Pumping charges per KL 1.10
As the above table indicates, open well water is much cheaper than Cauvery water.
Perception of Mr Raghuram Giridhar
I have been a very long-time resident of Vidyaranyapura and have witnessed the lakes
around (Doddabommasandra, Narasipura 1 & 2) overflowing during the Golden Years (pre -
2000). We were a small group of like-minded people involved in planting trees, cleaning the
streets, etc., and that is when the concept of conservation of a precious resource like water
was imbibed by us. I must say that Shri Vishwanath played a key role in influencing my
thoughts about water as a resource and its conservation, as well as concepts of shallow
aquifers and recharging groundwater.
From those times, I have always wanted to implement those practices, and I was able to do
that while constructing the house. Unlike other exercises, the implementation was very
cost-effective and simple. The concept of an open well with clear water, added to the
sentiment of my parents too, who felt that we were lucky and Goddess Gange had come to
our house. Apart from the sentiment of preserving nature, the economics of this is not at all
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5. a burden. A well can be created if one skips about 5 visits to a mall. Even if one does not
strike water, the channelling of rainwater to the recharge well will yield good water in about
one season of rainfall.
The fact that we get water from 90 km away and send the water 100 km away after using it
gives us a very large carbon footprint. If all of us can invest time and resources in a recharge
well (about 3ft*20ft), the burden on the river and the government will largely reduce and
improve the ecology to a large extent - that would be my request to the citizens of the
charming city of Bengaluru.
2. Rainwater Harvesting in Mr Sham Prasad’s house
Mr Sham Prasad is a resident of Doddabommasandra, Vidyaranyapura post, of Bengaluru
North. He has two houses (1200 and 700 sqft respectively). There are 8 residents residing in
the houses. The households demand 40,000 litres of water a month. The per capita water
consumption is 167 LPCD. Mr Sham Prasad has implemented rainwater harvesting by
directing rooftop rainwater into a sump, and the overflow is led into a recharge well. Here is
the story of rainwater harvesting in Mr Sham Prasad’s house.
Sources of water
Piped water: The household uses BWSSB’s Cauvery and borewell water. Mr Sham Prasad has
paid around Rs 70,000 to get a piped water connection. In a month, about 18-20KL of
Cauvery water and an additional 15KL of borewell water are used. He pays about Rs 300,
excluding the sanitation cess.
Borewell: Along with BWSSB’s water, the household also pumps water from a private
borewell. The borewell is 450 ft deep and was dug around 20 years ago. In the words of Mr
Sham Prasad, the borewell’s yield has not reduced over the years and is currently yielding
well. He uses borewell water in summer and when the piped water supply is reduced. On
average, he uses 15,000 litres of borewell water every month.
Rainwater harvesting
Mr Sham Prasad implemented rainwater harvesting in the year 2019. The rooftop rainwater
from the 1200 sqft roof area is led into a sump tank of 4500 litres capacity. The overflow
from the sump is led into the recharge well. The recharge well also receives surface runoff
water. Plumber Mohan dug the recharge well in April 2019. It is 2.5 ft in diameter and 20 ft in
depth. The recharge well is close to the borewell (3ft away) in order to recharge the
borewell. The following table shows the rainwater potential of Sham Prasad’s house:
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6. Rainwater harvesting potential
Type of catchment
Area
(sqm)
Runoff
coefficient
Runoff generated at
30mm rainfall (in KL)
Annual runoff at
974.5mm rainfall (in KL)
Rooftop area 111 0.9 3 97
Non-rooftop area 260 0.7 5 177
As per the above table, Mr Sham Prasad could harvest 97 KL of rooftop rainwater and 177 KL
of surface runoff annually.
First rain separator (left) and recharge well (right)
Water storage infrastructure: Mr Sham Prasad has two water-storing sumps. One is of 4500
litres, and the other is of 2500 litres capacity. Both the sumps are connected to each other.
Once the first sump fills up, water enters the second sump.
Water quality: Mr Sham Prasad was facing the accumulation of sand particles in the
borewell water. The initial thought was to install a sand filter. Mohan suggested passing the
borewell water through the masonry rainwater filter and the sand filter was unnecessary.
Mohan connected the borewell water to the masonry filter in September 2020. The issue of
sand particles in borewell water has been resolved completely.
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7. Production cost of water
Production cost of water is a method of arriving at the overall cost of different sources of
water per kilolitre. The following table shows the production cost of water for borewell
water and Cauvery water.
Production cost of different sources Cost per KL
Cauvery without sanitation cess 33
Cauvery with sanitation cess 36
Borewell (with recharge well) 103
Pumping charges per KL 1.10
As the above table indicates, borewell water is more expensive than Cauvery water.
"Rainwater harvesting is very useful. I have a sustained yield from my borewell after digging
the recharge well”.
-Sham Prasad
3. Rainwater harvesting at Kamesh Mahadevan’s house
Kamesh Mahadevan lives in an independent house with 3 residents in Vidyaranyapura. There
was a 30ft deep well in the compound that he said used to hold water throughout the year.
But it was located unfavourably from a Vaastu point of view, so the elders in the family got it
closed. Kamesh was keen to get another well dug, which he did, and led rooftop rainwater
into it.
Source of water: The old open well water was also once the house's water source. After the
well was closed, Cauvery was the only source of water. Every month the household
consumes 27KL of Cauvery water. The per capita water consumption is 300 LPCD.
Open well: Mr Kamesh got a new well dug in September 2020. Traditional well-digger
Muniyappa dug the well, and it is 3ft in diameter and 20 ft deep. While digging, water was
struck at a depth of 15 feet. The day after the rings were put in, the well had around 5 ft of
water. After it rained, the level went up to 13 ft. The well tends to have water when it rains
and is dry otherwise.
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8. Kamesh Mahadevan’s well
Rainwater harvesting
All the rainwater from the 500 sqft roof area has been routed into this well through a
wall-mounted filter. Surface runoff is not let into the well. The following table shows the
rainwater harvesting potential of Kamesh Mahadevan’s house:
Rainwater harvesting potential
Type of
catchment
Area
(sqm)
Runoff
coefficient
Runoff generated at
30mm rainfall (in KL)
Annual runoff at 974.5mm
rainfall (in KL)
Rooftop area 46 0.9 1.2 40
In a year Mr Kamesh Mahadevan can recharge 40KL of rainwater into the ground.
As more and more water percolates, the water table will rise, and the well will hold water
for longer and longer periods of time. Once this starts to happen, Kamesh plans to get the
water quality tested and see if it could be used for all domestic purposes in the house.
“Implementing rainwater harvesting and my efforts contributing to the groundwater
recharge and benefiting other borewells or wells in the neighbourhood gives me a sense of
satisfaction that I am contributing to society. I have not gained monetary benefits (returns
on investment) so far with RWH, but I did not expect it either. For me, what matters is my
contribution to society."
- Kamesh Mahadevan
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