2. • On 7 march 2017, Cape Town was
declared as Disaster area by the Mayor
as it had just 113 days of water left for
its residents
• Water supply per person was restricted
to 100 litres per day when the normal
requirement is 200 litres per day
• What happened to Cape Town is
happening to several other cities around
the world
3. CHENNAI
• The severe water crisis in Chennai came as
a warning for all Indians
•The city known for its floods became
severely drought affected in the recent
summer.
•Of Chennai's total requirement of 830 MLD
(million litres a day) water, the Chennai
Metro Water Supply was able to supply
only about 525 MLD during the worst days
of the crisis.
4. • According to United Nation's Food & Agricultural
organization, more than 90% of the world's
population is living in areas of the world which will
face severe water crisis very soon
• With a humongous popuation of 1.2 Billion, India is
one among them
10. RAINWATER
HARVESTING
• Is one of the practical solutions
to meet a big part of our water
requirement & minimise its
wastage
• Rainwater harvesting (RWH)
refers to collection of rain falling
on earth surfaces for beneficial
uses before it drains away as run-
off.
• Rainwater can be collected
from rivers or roofs, and in many
places, the water collected is
redirected to a deep pit (well,
shaft, or borehole), aquifer, a
reservoir with percolation, or
collected from dew or fog with
nets or other tool
11. Benefits of
RWH
They provide relatively high quality water (in
most areas)
• Direct capturing of rainwater significantly
reduces our reliance on water from dams/
reservoirs and canal systems.
• Reduces soil erosion and flooding typically
created by storm water run-off in urban areas
of India.
• Helps to create mass awareness and
appreciation for conservation of water
resources;
13. Stormwater
• Stormwater is rainwater that
runs off streets, lawns and
other sites.
• When stormwater is
absorbed into the ground, it
is filtered and ultimately
replenishes aquifers or flows
into streams and rivers
14. • Stormwater
harvesting or stormwater reuse is
the collection,
accumulation, treatment or
purification, and storing
of stormwater for its reuse. It
differs from rainwater harvesting as
the runoff is collected from drains or
creeks, rather than roofs. It can also
include other catchment areas from
man-made surfaces, such as roads,
or other urban environments such as
parks, gardens and playing fields.
• A main challenge stormwater
harvesting poses is the removal of
pollutants in order to make this
water available for reuse
16. Stormwater drain
Originally made to collect stormwater and
use it further for storage or proper
drainage
Present conditions in most parts of world
due to letting out pollutants into the drain
19. Catchment area
• The surface that receives rainfall directly is the catchment of rainwater
harvesting system. It may be terrace, courtyard, or paved or unpaved
open ground.
20. Rainwater from rooftop should be carried through down take
water pipes or drains
to storage/harvesting system. Water pipes should be UV resistant (ISI
HDPE/PVC pipes) of required capacity.
Transportation
21. First flush is a device used to flush off the water received in first shower. The first shower of
rains needs to be flushed-off to avoid contaminating storable/rechargeable water by the
probable contaminants of the atmosphere and the catchment roof. It will also help in cleaning
of silt and other material deposited on roof during dry seasons Provisions of first rain
separator should be made at outlet of each drainpipe.
First Flush
22. All collected rain water are store in tank or barrels used.
Storage system
23. It is a system to delivered of water for uses. There are use of pumps
to take out water from tank and deliver for many purpose .
Water is deliver by pips .
Delivery system
24. Filters are used for treatment of water to effectively remove
turbidity, colour and microorganisms. After first flushing of rainfall,
water should pass through filters. There are different types of filters
in practice, but basic function is to purify water.
Filtration system
25. Sand Gravel Filter
• These are commonly used filters, constructed by
brick masonry and filleted by pebbles, gravel, and sand
as shown in the figure. Each layer should be separated
by wire mesh.
26. Charcoal filter can be made in-situ or in a drum.
Pebbles, gravel, sand and charcoal as shown in the figure should fill the
drum or chamber. Each layer should be separated by wire mesh. Thin
layer of charcoal is used to absorb odor if any.
Charcoal Filter
27. This filter can be made by PVC pipe of 1 to 1.20 m length; Diameter of
pipe depends on the area of roof. Six inches dia. pipe is enough for a
1500 Sq. Ft. roof and 8 inches dia. pipe should be used for roofs more
then 1500 Sq. Ft. Pipe is divided into three compartments by wire
mesh.
PVC- Pipe filter
29. Planning of RWH system
The estimation of quantity of water that can be harvested is the first step in planning and
design of RWH systems. The quantity depends on the area of catchment and the annual
average rainfall of the region.
Supply of rainwater can be estimated from the monthly average rainfall data available
from the local meteorological or public works department, and texture and extend of the
catchment area
To estimate the storage capacity requirement, a water balance statement for a each
month of a calendar year has to be prepared and the cumulative excess water (supply
minus demand) available at the end of each month calculated. The highest cumulative
excess water will be the required capacity for the storage tank.
31. METHODS
Storage for direct use
Recharging groundwater aquifers
Recharge Well
Recharging of borewell
Recharge pit
Recharge shaft
Recharge trench
Percolation tank
32. Storage for direct use
• In this method rainwater collected
from the roof of the building is
diverted to a storage tank. The
storage tank has to be designed
according to the water
requirements, rainfall and
catchment availability.
• Each drainpipe should have mesh
filter at mouth and first flush
device followed by filtration
system before connecting to the
storage tank. It is advisable that
each tank should have excess
water over flow system.
• Excess water could be diverted to
recharge system. Water from
storage tank can be used for
secondary purposes such as
washing and gardening etc. This is
the most cost effective way of
rainwater harvesting.
34. Construction of Recharge well
STEP 1: Excavating the Earth
2:Making a borehole to facilitate
groundwater recharging
3: Providing masonry or RCC walls in
the excavated portion and thereafter
providing the filter materials.
4: Covering the tank made with a RCC
or stone slab provided with a manhole
35. Recharging of
Borewell
• Rainwater collected from
rooftop of the building is
diverted through drainpipes
to settlement or filtration
tank. After settlement
filtered water is diverted to
bore wells to recharge deep
aquifers. Abandoned bore
wells can also be used for
recharge.
36. • A pond is constructed nearby the borewell site in a position to gather the
run off water from the monsoonal rains.
• A pit is dug around the actual borewell casing
• The bottom of this pit is lined with filtration material Next slits are cut into
the borewell casing using a cutting machine, and the casing is then
wrapped with nylon mesh so solids cannot enter the casing pipe.
• cement rings are placed around the borewell casing and the spaces
between them are filled with cement to seal them. This ‘false well’ is then
filled with 20mm stones.
• A second ‘false well’ is constructed next to the first ‘false well’
• A 3 inch feeder pipe is fitted coming from the pond to a hole in the first
cement ring of this empty well. This brings the water from the pond.
• During rainy season the water flows from the pond into the first empty well
where it percolates down through the filtration material and subsequently
up into the second well around the borewell casing. It then enters through
the slits and filters down into the underlying aquifer where it is stored for
the following dry season.
37. Recharge Pit
• Recharge pits are small pits of
any shape rectangular,
square or circular, contracted
with brick or stone masonry
wall with weep hole at
regular intervals. Top of pit
can be covered with
perforated covers. Bottom of
pit should be filled with filter
media.
• Usually the dimensions of
the pit may be of 1 to 2 m
width and 2 to 3 m deep
38. Recharge Shaft
• Soak away or recharge
shafts are provided where
upper layer of soil is alluvial
or less pervious. These are
bored hole of 30 cm dia. up
to 10 to 15 m deep,
depending on depth
of pervious layer. Bore
should be lined with
slotted/perforated PVC/MS
pipe to prevent collapse of
the vertical sides.
39. Recharge Trench
• Recharge trench in provided
where upper impervious
layer of soil is shallow. It is
a trench excavated on the
ground and refilled with
porous media like pebbles,
boulder or brickbats. it is
usually made for harvesting
the surface runoff.
40. Percolation Tank
• Percolation tanks are
artificially created surface
water bodies, submerging a
land area with adequate
permeability to facilitate
sufficient percolation to
recharge the groundwater.
These can be built in big
campuses where land is
available and topography is
suitable
56. • A R Shivakumar
• A senior scientist at the
Karnataka State Council of
Science and Technology
(KSCST) at Indian Institute
of Science (IISc) is a
vociferous proponent of
RWH, he does not have a
Bangalore corporation
water connection in his
home and he has been
relying entirely on
collected rainwater to
serve all his family’s needs
for over 23 years.
57. In 1995, when Shivakumar
started building his house, he did
a lot of research to look for
alternatives that would fulfill his
family’s needs without harming
the environment. His first step
was to analyse the water bills of
residents of the locality to map
the water consumption of an
average family. He found that his
findings matched the water
consumption norms published by
WHO – a family of four uses
approximately 500 litres of water
per day.
58. • Next, he sat and tabulated the
rainfall data in the city over the last
100 years. He was surprised to
discover that as per the data, there is
more than enough rainfall in the
city, even in the worst monsoon-
deficient years.
• The only catch was that while it
rained for about 60-70 days in a year,
the water had to last for 365 days.
59. He built a series of RWH
tanks that could store
almost 45,000 litres
of water to tide over these
100-odd days. Also, to
ensure that a motor was
not needed he stored part
of the water on the rooftop
to avoid it being sent down
and pumped up again.
60. Each tank has been fitted with
an innovative filter device that
has been built and patented by
Shivakumar himself. Called
Pop-Up Filter, the device uses a
simple silver sheet to remove
all impurities from the
collected rainwater before
channeling it around the
house. It can be vertically
installed on the walls of a small
buildings
63. The Golden Desert, Thar
• Receives less than 16cm of rain every
year
• Groundwater is 100 meters deep and
most of it is saline, not fit for drinking
65. A city in the middle of the harsh Thar desert which is over 800 years old & has
relied on water collected from rainwater harvesting since its inception
Life thrived in full fledge in between the Thar desert without the help of any
modern technologies.
66. They made 52 water
bodies around the city to
store the harvested water
67. Paar System
• Paar is the most common water harvesting
practice here.
• It is a common place where the rainwater
flows from the agar (catchment) and in the
process percolates into the sandy soil.
• In order to access the rajani pani
(percolated water) kuis or beris are dug in
the agor (storage area). Kuis or beris are
normally 5 metres (m) to 12 m deep.
• The structure is constructed through
traditional masonary technology.
kui
68. Rapat
• A rapat is a percolation tank, with a bund
to impound rainwater flowing through a
watershed and a waste weir to dispose of
the surplus flow.
• If the height of the structure is small, the
bund may be built of masonary, otherwise
earth is used.
• Rapats and percolation tanks do not
directly irrigate land, but recharges well
within a distance of 3-5 km downstream.
69. Kund
• kund or kundi looks like an upturned cup
nestling in a saucer. These structures
harvest rainwater for drinking
• Essentially a circular underground
well, kunds have a saucer-shaped
catchment area that gently slopes towards
the centre where the well is situated.The
sides of the well-pit are covered with
(disinfectant) lime and ash.
• The depth and diameter of kunds depend
on their use (drinking, or domestic water
requirements).
70. Baori
• Baoris or bers are Stepwells,
found in Rajasthan, that are
used mainly for drinking.
• Most of them are very old and
were built by banjaras (mobile
trading communities) for their
drinking water needs.
• They can hold water for a long
time because of almost
negligible water evaporation.
71. Construction -
• The builders dug deep trenches into the earth for dependable, year-
round groundwater.
• They lined the walls of these trenches with blocks of stone, without
mortar, and created stairs leading down to the water.
• Proportions in relationship to the human body were used in their
design
• The majority of surviving stepwells originally served a leisure
purpose as well as providing water. This was because the base of
the well provided relief from daytime heat, and this was increased if
the well was covered.
72. singapore
• Singapore is a highly
developed city which
imports 60% of its
freshwater
requirement
• It's a very small
island so they need
to make use of as
much space
available as possible
to catch rainfall
73. So In 2008, they made the Marina Barrage to increase their rainwater
harvesting capacity.
74. • With a catchment area of 10,000
hectares, Marina catchment is
the island’s largest and most
urbanised fresh water reservoir.
Marina Reservoir has increased
Singapore’s water catchment
from half to two-thirds of the
country’s land area.
75. Marina Barrage brings
about three benefits:
• 1. A source of water
supply.
It has a dam built across
the 350-metre wide
Marina Channel to keep
out seawater, creating one
of the largest freshwater
reservoirs in the world. It's
about 1/6th the size of
Singapore & thus can store
huge amount of
freshwater
76. 2. Flood Control
Marina Barrage is part of a
comprehensive flood control
scheme to alleviate flooding
in the low-lying areas in the
city. During heavy rain, the
series of nine crest gates at
the dam are activated to
release excess stormwater
into the sea when the tide is
low. In the case of high tide,
giant pumps can drain
excess stormwater into the
sea.
77. 3. Lifestyle Attraction
Unaffected by Tides, water
levels in the reservoir are
kept constant the whole
year.
This makes it ideal
for recreational activities
such as boating, kayaking
and dragonboating.
