Water is essential for all life of forms on earth-including human, animal and vegetation. It is therefore important that adequate supplies of water be developed to sustain such life Where there is no surface water, where groundwater is deep or inaccessible due to hard ground conditions, or where it is too salty, acidic or otherwise unpleasant or unfit to drink, another source must be sought. In areas that have regular rainfall, the most appropriate alternative is the collection of rainwater, called rainwater harvesting .

1. Rain water harvesting
T.W.G.F.A Nijamdeen
Reg.no:612260302

2. Introduction
• Water is essential for all life of forms on earth-including
human, animal and vegetation.
• It is therefore important that adequate supplies of water be
developed to sustain such life
• Where there is no surface water, where groundwater is deep
or inaccessible due to hard ground conditions, or where it is
too salty, acidic or otherwise unpleasant or unfit to drink,
another source must be sought.
• In areas that have regular rainfall, the most appropriate
alternative is the collection of rainwater, called rainwater
harvesting .

3. What is rain water harvesting?
• The term ‘rainwater harvesting’ is usually taken to mean
the immediate collection of rainwater running off
surfaces upon which it has fallen directly.
• This definition excludes run-off from land watersheds
into streams, rivers, lakes, etc.
• Hence it is the catching of rain water when it falls and
storing to use during the non rainy season.

4. The technology of rain water
harvesting
• Can be divided according to the purpose and the source of
collecting water.
• Methods
- Roof top harvesting
- Run off harvesting
• These methods can be selected considering,the purpose,
the type and quantity of storage,Catchment state ect.

5. • Roof top harvesting
This method include the catchment area as the roof top in rural
and urban area.
This include Rooftop of houses,flats,factories,offices,complexes.

6. Runoff harvesting
Here the runoff water is collected
Gardens,driveways,landscapes,open fields,parks,roads and
pavements and other open areas of the environment can be used
to harvest the rain water runoff.
Using this method, it is possible to collect water from a larger
area.
This is particularly advantageous in areas of low rainfall.
Drive ways

7. Components of rain water
harvesting
• Catchment area
Rainwater can be collected from most forms of roof.
Tiled roofs, or roofs sheeted with corrugated mild steel etc are
preferable, since they are the easiest to use and give the
cleanest water.
Thatched or palm leafed surfaces are also feasible, although
they are difficult to clean and can often taint the run-off.
Asbestos sheeting or lead-painted surfaces should be avoided
Roof top Driveway

8. • Gutters and pipes
In a roof top system gutters and pipes are used to collect and
transport water to the storage tanks.
These pipes and gutters can be made of PVC or metal,but PVC is
widely used.
Gutters and pipes

9. • Filters
They are used to filter out the debris that comes with the roof
top water and prevent them being added to the storage tank.
- Mesh filters
- First-flushing devices
- sediment discharge tap
Mesh filter and first flushing device.

10. • Storage facility
Storage tank is the structure where the water is stored.
This can be varied according to the
• shape- cylintrical,rectangular,hexangular,square
• Material of construction- rein forced cement concrete
(RCC),Ferro cement,Masonery,Plastic or metal sheets.
• Position of tank-Above groung,Partly underground,fully
underground

11. • Storage tanks in different shapes and
positions

12. • Devices to draw water out
This include devices such as hand pumps, motorized pumps or
taps.
The device depends on the position of the tank and the use of
water.

13. Advantages of rain water harvesting
• Relatively cheap materials can be used for construction of
containers and collecting surfaces
• Construction methods are relatively straightforward
• Low maintenance costs and requirements
• Environment friendly
• Increase the ground water level and quality.
• Mitigates the effects of drought.
• Reduces the runoff
• Reduces the soil erosion
• Helps in reducing water and electricity bills
• Provides a supply of safe water close to homes, schools or clinics,
encourages increased consumption, reduces the time women and
children spend collecting water, reduces back strain or injuries from
carrying heavy water containers

14. Disadvantages of rain water harvesting
• Supplies can be contaminated by bird/animal droppings on
catchment surfaces and guttering structures unless they are
cleaned/flushed before use
• Poorly constructed water jars/containers can suffer from
algal growth and invasion by insects, lizards and rodents. They
can act as a breeding ground for disease vectors if they are
not properly maintained
• Regular maintenance should be needed
• Unpredictable rain fall

15. Importance of rain water harvesting
and future
• Rain water harvesting plays an important role in
agriculture
• Useful for urban areas
• It is important to save the water for the future.
• Thus it is important to improve rain water harvesting
through technical and financial prospects.

16. Conclusion
• ‘rainwater harvesting’ is usually taken to mean the
immediate collection of rainwater running off surfaces
upon which it has fallen directly.
• So collecting rain water is cost effective and a best
alternative to the scarcity for water world wide.
• Therefore rain water harvesting should be improved to
gain sustainability in various aspects in rural as well as in
urban areas.

17. Thank you