RAIN WATER HARVESTING

GAUTAM BANERJEE

UP Jal Nigam

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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 etc.

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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

(after filtering) top layer can hold 1.2 Lac tons of water

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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 urban areas

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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 catchmentThe 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 the water is to be made.

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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 co-efficient 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 =1.2 m dia 1.8 m height

No. of Tanks 4

Volume of Tanks 3.14x1.2x1.2x1.5/4

2.03 cum

2000 liters

Volume of of 4 tanks =

4x2000

8000 Liters

(this can be designed as per requirement)

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Cost of Material for Tank• 1. Cement 8 bags*Rs. 140.00 1120.00• 2. Grit .25 Cum 200.00• 3. Sand .4 Cum 100.00• 4. Perforated Cement rings 5 No. 1000.00• 5. P/fabricated Cement rings 4 No. 400.00• 6. PVC pipe 63mm dia.*10M 200.00• 7. P/fabricated Asbestos 10mm dia.*10mm

Gutters 250.008. Mason/ Labor charges. 1000.009. Transportation 130.00

Total 4400.00

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Cost of Material for Filtration Tank

• 1. P/fabricated cement rings 5*Rs. 40.00 200.00• 2. Cement 2 bags*Rs. 140.00 280.00• 3. Sand 2 bags 50.00• 4. Grit 4 bags 50.00• 5. Charcoal 20 Kg*Rs. 8.00 160.00• 6. Sand for Plastering 4 bags 100.00• 7. Mason/ Labor 500.00• 8. White washing 40.00• 9. Transportation 50.00

Total1430.00

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• Total Cost of construction Rs. 4400.00+

Rs. 1430.00= Rs. 5830.00

The cost on O/ M-

1. 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 bone-seeking 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 & Thyroid disorders

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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 all age groups in India.

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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 459

(based on RGNDWM 91)

Range No. of villages

1.5-2 ppm 159

2-2.5 ppm 149

2.5-3 ppm 97

3-4 ppm 40

4-8 ppm 14

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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

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General distribution of Aquifers of Unnao

GL Surface water (sweet)

200 M (+/- 20%)Saline water

Middle system of Aquifers

Lower system of Aquifers

Sweet water

70 m(+15% variation)

Upper system of Aquifers

Water contains fluoride

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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