Rain water harvestingT.W.G.F.A Nijamdeen

Reg.no:612260302

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 .

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.

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.

• 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.

Runoff harvestingHere 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

Components of rain water harvesting

• Catchment areaRainwater 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

• Gutters and pipesIn 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

• FiltersThey 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.

• 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

• Storage tanks in different shapes and positions

• Devices to draw water outThis include devices such as hand pumps, motorized pumps or

taps.

The device depends on the position of the tank and the use of

water.

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

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

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.

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.

Thank you