RAIN WATER HARVESTING
GAUTAM BANERJEE
UP Jal Nigam
Reasons of Shortage of Water
• Population increase
• Industrialization
• Urbanization
(a) Increase in per capita utilization
(b) Less peculation area
• In places where rain fed/ irrigation based crops
are cultivated through ground water
• Decrease in surface area of Lakes, talab, tanks
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etc.
Reasons of Shotrage of Water
Continued…..
• Deforestation
(i) Less precipitation
(ii) Absence of Barriers
(a) Rain drops checked by leaves of tree
(b) Water slowly descends through twigs & trunk
© Humus – acts as reservoir
(d) Tiny creatures – helps percolation
1 hectare of forest-6-7 Lac ton of water
2
3
(after filtering) top layer can hold 1.2 Lac tons of water
What is the solution ?
• Rain water is the ultimate source of fresh water
• Potential of rain to meet water demand is
tremendous
• Rain water harvesting helps to overcome water
scarcity
• To conserve ground water the aquifers must be
recharged with rain water
• Rain water harvesting is the ultimate answer
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Why Rain water be harvested
• To conserve & augment the storage of
ground water
• To reduce water table depletion
• To improve the quality of ground
water
• To arrest sea water intrusion in
coastal areas
• To avoid flood & water stagnation in
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urban areas
What is rain water harvesting ?
• It is the activity of direct collection of rain
water
• Rain water can be stored for direct use or can
be recharged into the ground water aquifer
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The roof catchment are selectively
cleaner when compared to the ground
level catchment
• Losses from roof catchment are minimum
• Built & Maintained by local communities
• No Chemical contamination & only required
filtration
• Available at door step with least cost
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The typical roof top rain water
harvesting system comprises
•
•
•
•
•
Roof catchment
Gutters
Down pipe & first flushing pipe
Filter Unit
Storage Tank
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Roof catchment
The roof of the house is used as the catchment for
collecting rain water. The style construction and
material of the roof effect its suitability as a
catchment, Roofs made of corrugated iron sheet ,
asbestos sheet, Tiles or Concrete can be utilized
for harvesting the rain water
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Gutters
Gutters are channels fixed to the edges of
roof all around to collect & transport the
rainwater from the roof. Gutters can be
made in semi-circular and rectangular shape
with cement pipe, plain galvanized iron
sheet, PVC pipes, bamboos etc. Use of
locally available material reduce the overall
cost of the system.
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Down Pipe
It is the pipe which carries the rainwater
from the gutters to the filter & storage tank.
Down pipe is joined with the gutters at one
end & the other end is connected to the
filter unit of the storage tank. PVC or GI
pipe of 50mm to 75mm (2 to”) are
commonly used for down pipe. Bamboo can
be also used wherever available and
possible
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First Flush Pipe
Debris, dust & dirt collect on the roof
during non rainy periods when the first rain
arrive. A first flush system arrangement is
made to avoid the entering unwanted
material into the Filter media & storage
tank. This is a simple manually operated
arrangement or semi-automatic system with
a valve below the ‘T’ junction
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Filter Unit
The filter unit is a container or chamber
filled with filter media such as coarse sand,
charcoal, coconut fiber, pebbles & gravels
to remove the debris & dirt from water that
enters the tank. The filter unit is placed over
the storage tank or separately. It may be of
Ferro cement filter unit, Aluminum, Cement
rings or Plastic bucket etc.
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Storage Tank
It is used to store the water that is collected from the roof
through filter. For small scale water storage plastic
buckets, jerry cans, clay or cement jars, ceramic jars,
drums may be used. For larger quantities of water, the
system will require a bigger tank with cylindrical or
rectangular or square in shape constructed with Ferro
cement or cement rings or plain cement concrete or
reinforced cement concrete or brick or stone etc. The
storage tank is provided with a cover on the top to avoid
the contamination of water from external sources. The
storage tank is provided with pipe fixtures at appropriate
places to draw the water to clean the tank & to dispose of
extra water. A provision for keeping the vessel to collect
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the water is to be made.
Size of Storage Tank
• Based on
– No. of person in the House hold
– Per capita water requirement
– No. of days for which water is required
Example
Drinking water requirement for a household with 5
family members, period 8 months & 6 lpcd
= 5x 180x 6
= 7200 Liters
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Water available from Roof
Annual rainfall (in mm) x roof area (in sq. m) x coefficient of run off for roof
co-efficient of run off
GI sheet
0.9
Asbestos
0.8
Tiled
0.75
Plaster on bricks/ Concrete
0.7
Water available from roof top 800mmx 20 sq.m=12800
Liters per annum
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Water available from Roof
continued……
Size of Tank
No. of Tanks
Volume of Tanks
=1.2 m dia
1.8 m height
4
3.14x1.2x1.2x1.5/4
2.03 cum
2000 liters
Volume of of 4 tanks =
4x2000
8000 Liters
(this can be designed as per26requirement)
Cost of Material for Tank
•
•
•
•
•
•
•
1. Cement
8 bags*Rs. 140.00
2. Grit
.25 Cum
3. Sand
.4 Cum
4. Perforated Cement rings 5 No.
5. P/fabricated Cement rings 4 No.
6. PVC pipe
63mm dia.*10M
7. P/fabricated Asbestos 10mm dia.*10mm
Gutters
8. Mason/ Labor charges.
9. Transportation
Total
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1120.00
200.00
100.00
1000.00
400.00
200.00
250.00
1000.00
130.00
4400.00
Cost of Material for Filtration Tank
•
•
•
•
•
•
•
•
•
1. P/fabricated cement rings 5*Rs. 40.00
2. Cement
2 bags*Rs. 140.00
3. Sand
2 bags
4. Grit
4 bags
5. Charcoal
20 Kg*Rs. 8.00
6. Sand for Plastering
4 bags
7. Mason/ Labor
8. White washing
9. Transportation
Total
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200.00
280.00
50.00
50.00
160.00
100.00
500.00
40.00
50.00
1430.00
•
Total Cost of construction Rs. 4400.00+
Rs. 1430.00= Rs. 5830.00
The cost on O/ M1. White washing
100.00
2. Water testing
200.00
(2 times a year)
300.00
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Flooded with Fluoride-G/ water is not potable
Fluoride is an acute toxin with a rating slightly
higher then lead. It is infect, one of the most boneseeking elements known to human beings &
groundwater in India shows the presence of
unhealthy quantities of fluoride. A worrying
scenario: daily ingestion of 2 milligram (mg) of
fluoride could result in creeping Skeletal fluorosis
after 40 years. Excess fluoride causes several
diseases like Osteoporosis, Arthritis, Brittle bones,
Cancer, Infertility in women, Brain damage,
Alzheimer’s disease & 30Thyroid disorders
Flooded with Fluoride-G/ water is not potable
The very nature of fluoride increases this danger
manifold. Almost half of each day’s fluoride intake is
retained & is absorbed by the bones & teeth. It was
Gerald Cox, of the Mellon Institute in the US, who
first found in 1938 that while 1mg/ liter of fluorine in
water prevents dental caries over 1.5mg/l causes
mottled teeth. The bureau of Indian Standards (BIS)
standard for fluoride content is 1-1.5mg/l. It is
believed that levels above or below this could cause
de4ntal decay. Ironically, there is an increased
incidence of dental caries, yellow teeth & twisted
limbs among people of all31 age groups in India.
Flooded with Fluoride-G/ water is not potable
A recent publication of the Geographical Survey of
India (GSI) names areas that should go on fluoride
red alert: Fazilka & Jalalabad in the border district
of Ferozpur in Punjab, parts of Gurgaon, Rewari,
Mahendranath, Hisar, Fatehabad & Faridabad
district in Haryana, Unnao, Rae Barely &
Sonebhadra district in Uttar Pradesh, Sidhi district
in Madhya Pradesh, Beed district in Maharastra,
Nalgonda district in Andhra Pradesh and Dindigul
district in Tamilnadu.
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Fluoride effected Villages
• Fluoride effected villages
(based on RGNDWM 91)
Range
1.5-2 ppm
2-2.5 ppm
2.5-3 ppm
3-4 ppm
4-8 ppm
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459
No. of villages
159
149
97
40
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Fluoride effected Villages
continued……..
•Range of Concentration
1.5-8.4 ppm
•Lower range of Concentration
1.5-2.5 ppm
(about 67% villages)
•Cause
Salt concentration neat aquifers
•Trend
No. of villages increasing
Reason
(i) Heavy withdrawal of water from upper strata
(ii)Less charging of Strata due to Silt/ clayey
upper layer of Soil 34
General distribution of Aquifers of Unnao
GL
Surface water (sweet)
Upper system of Aquifers
70 m(+15% variation)
Water contains fluoride
Middle system of Aquifers
200 M (+/- 20%)
Saline water
Lower system of Aquifers
Sweet water
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How the problem can be minimized
1 By providing pipe water system with source (electric
based)
(a) Surface water
(b) Deep tubewells
2 Recharging stratas through rainwater harvesting
methods
(No. of villages of lower range concentration can be
decreased)
3 Storing rain water for drinking purpose
(a) In areas where electricity problem is more
(b) In areas where concentration is more
© In areas where
PWS is uneconomical
(d) In areas where dependable
source is not available
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Thank You
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