Rain water Harvesting

1. By
SANJAY SINGH

2. WHAT IS RAINWATER
HARVESTING ?
RAINWATER HARVESTING IS AN
INNOVATIVE ALTERNATIVE WATER
SUPPLY APPROACH ANYONE CAN
USE. RAINWATER HARVESTING
CAPTURES, DIVERTS, AND STORES
RAINWATER FOR LATER USE

3. Process of Rainwater Harvesting
• Rainwater harvesting is a way of catching
rain, filtering it, and using it for drinking
and non-drinking purposes

4. Type of Rain water Harvesting
Type of rain
water
harvesting
Rooftop
Rainwater
Harvesting
Underground
System

5. Advantages
• Rainwater harvesting provides an
independent water supply during
regional water restrictions and in
developed countries is often used to
supplement the main supply.
continue….

6. Advantages
It provides water when there is a drought,
prevents flooding of low-lying areas,
replenishes the ground water table, and
enables dug wells and bore wells to yield in
a sustained manner. It also helps in the
availability of clean water by reducing the
salinity and the presence of iron salts.
Continue…….

7. Advantages
• Makes use of a natural resource and reduces
flooding, storm water runoff, erosion, and
contamination of surface water with pesticides,
sediment, metals, and fertilizers
•Promotes both water and energy conservation
•No filtration system required for landscape
irrigation
continue…….

8. Advantages
•Excellent source of water for landscape
irrigation, with no chemicals such as fluoride
and chlorine, and no dissolved salts and
minerals from the soil.
•Home systems can be relatively simple to
install and operate and it may reduce your
water bill.

9. Quality
•The concentration of contaminants is reduced
significantly by diverting the initial flow of runoff
water to waste.
• Improved water quality can also be obtained by
using a floating draw-off mechanism (rather than
from the base of the tank) and by using a series
of tanks, with draw from the last in series. The
stored rainwater may need to be analyzed
properly before use in a way appropriate to its
safety.
Continue………

10. Quality
The quality of collected rainwater is
generally better than that of surface
water. Contamination is always possible
by airborne dust and mists, bird feces,
and other debris, so some treatment is
necessary, depending on how the water
will be used.

11. System setup
Rainwater harvesting systems can be installed
with minimal skills The system should be sized to
meet the water demand throughout the dry
season since it must be big enough to support
daily water consumption. Specifically, the rainfall
capturing area such as a building roof must be
large enough to maintain adequate flow.
Likewise, the water storage tank should be large
enough to contain the captured water

12. Present day RWH in india
In the state of Tamil Nadu, rainwater
harvesting was made compulsory for
every building to avoid ground water
depletion. It proved excellent results
within five years, and every other state
took it as role model. Since its
implementation, Chennai saw a 50
percent rise in water level in five years
and the water quality significantly
improved

13. Present day RWH in india
In Rajasthan, rainwater harvesting
has traditionally been practiced by
the people of the Thar Desert.
There are many ancient water
harvesting systems in Rajasthan,
which have now been revived
Kerala

14. Present day RWH in india
•At present, in Pune (in Maharashtra),
rainwater harvesting is compulsory for any
new society to be registered
•An attempt has been made at Dept. of
Chemical Engineering, IISc, Bangalore to
harvest rainwater using upper surface of a
solar still, which was used for water
distillation

15. Harvested Rainwater Application
• Residential/Small Commercial
• Multi-family Residential
• Commercial/Industrial

16. Residential/Small Commercial

17. Large Commercial/Industrial

19. Components
Vortex Filters
for fine filtration
and oxygenation
Floating Filter
takes the cleanest
water
Smoothing Inlet
stable sedimentation
and oxygenation
Multifunction overflow
for a clean water
surface
protects water
quality

21. Harvesting System
Broadly rainwater can be harvested for
two purposes
•Storing rainwater for ready use in
containers above or below ground
•Charged into the soil for withdrawal later
(groundwater recharging)
Source: A Water Harvesting Manual For Urban Areas

22. RAIN WATER HARVESTING TECHNIQUES :
There are two main techniques of rain water
harvestings.
• Storage of rainwater on surface for future
use.
• Recharge to ground water.
The storage of rain water on surface is a
traditional techniques and structures used
were underground tanks, ponds, check
dams, weirs etc

23. Recharge to ground water is a new concept
of rain water harvesting and the
structures generally used are :-
Pits :- Recharge pits are constructed for
recharging the shallow aquifer. These are
constructed 1 to 2 m, wide and to 3 m.
deep which are back filled with boulders,
gravels, coarse sand.

24. • Trenches:- These are constructed
when the permeable stram is available
at shallow depth. Trench may be 0.5 to
1 m. wide, 1 to 1.5m. deep and 10 to
20 m. long depending up availability of
water. These are back filled with filter
materials.
• Dug wells:- Existing dug wells may be
utilised as recharge structure and water
should pass through filter media before
putting into dug well.

25. Hand pumps :- The existing hand pumps
may be used for recharging the
shallow/deep aquifers, if the availability of
water is limited. Water should pass through
filter media before diverting it into hand
pumps.
Recharge wells :- Recharge wells of 100 to
300 mm. diameter are generally
constructed for recharging the deeper
aquifers and water is passed through filter
media to avoid choking of recharge wells.

26. Recharge Shafts :- For recharging the shallow
aquifer which are located below clayey
surface, recharge shafts of 0.5 to 3 m.
diameter and 10 to 15 m. deep are
constructed and back filled with boulders,
gravels & coarse sand.
Lateral shafts with bore wells :- For
recharging the upper as well as deeper
aquifers lateral shafts of 1.5 to 2 m. wide &
10 to 30 m. long depending upon availability
of water with one or two bore wells are
constructed. The lateral shafts is back filled
with boulders, gravels & coarse sand.

27. 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.

28. Reasons of Shotrage of
Water
• 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

29. 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

30. 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

31. 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

32. Rain Water Harvesting?.
• Rain Water Harvesting RWH- process of collecting,
conveying & storing water from rainfall in an area – for
beneficial use.
• Storage – in tanks, reservoirs, underground storage-
groundwater
• Hydrological Cycle

33. Rain Water Harvesting?.
• RWH - yield copious amounts of water. For an
average rainfall of 1,000mm, approximately four million
litres of rainwater can be collected in a year in an acre
of land (4,047 m2), post-evaporation.
•As RWH - neither energy-intensive nor labour-
intensive
•It can be a cost-effective alternative to other water-
accruing methods.
• With the water table falling rapidly, & concrete
surfaces and landfill dumps taking the place of water
bodies, RWH is the most reliable solution for
augmenting groundwater level to attain self-sufficiency

34. Rain Water Harvesting– Advantages
1.Provides self-sufficiency to water supply
2.Reduces the cost for pumping of ground water
3.Provides high quality water, soft and low in minerals
4.Improves the quality of ground water through
dilution when recharged
5.Reduces soil erosion & flooding in urban areas
6.The rooftop rain water harvesting is less expensive
& easy to construct, operate and maintain
7. In desert, RWH only relief
8. In saline or coastal areas & Islands, rain water
provides good quality water

35. Appropriate Technology
Water conservation
and groundwater
recharge techniques
Water harvesting
cum supplementary
irrigation techniques

36. 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

37. Rain water harvesting system
The typical roof top rain water harvesting system
comprises
• Roof catchment
• Gutters
• Down pipe & first flushing pipe
• Filter Unit
• Storage Tank

38. 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

39. 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.

40. 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

41. 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

42. 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.

43. 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.

44. 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

45. 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

46. 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
Total 1430.00

47. 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 250.00
8. Mason/ Labor charges. 1000.00
9. Transportation 130.00
Total 4400.00

48. • 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

49. Water available from Roof continued……
Size of Tank =1.2 m dia 1.8 m height
No. of Tanks 4
Volume of Tanks3.14x1.2x1.2x1.5/4
2.03 cum
2000 liters
Volume of of 4 tanks =
4x2000
8000 Liters
(this can be designed as per requirement)

50. 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

51. • ATTRIBUTES OF GROUNDWATER :
• There is more ground water than surface
water
• Ground water is less expensive and
economic resource.
• Ground water is sustainable and reliable
source of water supply.
• Ground water is relatively less vulnerable
to pollution
• Ground water is usually of high
bacteriological purity.
• Ground water is free of pathogenic
organisms.

52. • Ground water needs little treatment before use.
• Ground water has no turbidity and colour.
• Ground water has distinct health advantage as
art alternative for lower sanitary quality surface
water.
• Ground water is usually universally available.
• Ground water resource can be instantly
developed and used.There is no conveyance
losses in ground water based supplies.
• Ground water has low vulnerability to drought.
• Ground water is key to life in arid and semi-arid
regions.
• Ground water is source of dry weather flow in
rivers and streams.

53. THANKS