consists information about rain water harvesting reason , advantages, methods involved , components

1. Nimisha
Anubha
Sunayana
Tanisha
Molliee

2. Rainwater Harvesting
Rainwater harvesting is the
accumulation and deposition of
rainwater for reuse before it
reaches the aquifer. It is the
process of intercepting storm-
water runoff and putting it to
beneficial use.

3. • To arrest groundwater
decline and augment
ground water table
• To beneficiate water
quality in aquifers
• To conserve surface water
runoff during monsoon
• To reduce soil erosion
• To inculcate a culture of
water conservation.

4. Rainwater harvesting provides an independent water supply during
regional water restrictions and in developed countries is often used
to supplement the main supply.
It provides water when there is a drought, can help mitigate flooding
of low-lying areas, and reduces demand on wells which may enable
ground water levels to be sustained.
It also helps in the availability of potable water as rainwater is
substantially free of salinity and other salts.
By harvesting and using rainwater we can: Increase water availability
for on-site vegetation Reduce on-site flooding and erosion Reduce
water bills and groundwater pumping Extend the life of landscaping
(rainwater is usually low in salt content and relatively high in
nitrogen)

5. 1.PASSIVE RAINWATER COLLECTION:
Passive rainwater collection is the act of
slowing down rainwater and letting it
infiltrate on site rather than channeling it
into the storm drain system. A passive
system uses earthworks to control surface
water flow and uses the soil as the storage
container. Intercepted rainwater can be
collected, slowed down and retained or
routed through the site landscape using
microbasins, swales and other water
harvesting structures. Redirecting the roof
downspout into a landscaped area is an
example of pasive rainwater harvesting

6. 2. ACTIVE RAINWATER
HARVESTING:
Active rainwater collection systems
integrate a storage container, a tank
or cistern, into the system to catch
rainwater runoff for later use on the
property. These tanks can be installed
above or below ground. Above ground
systems usually rely on gravity to
disperse the water and serve smaller
areas. The in ground system requires
a pump but can provide water
throughout the site.

7. COMPARISON:
1. The active systems bring a great advantage :
water can be stored and used when the soils are dry (instead of while the
ground is soaked from the same rain that filled your tank).
2. Active systems are also more complex than passive systems, cost more
and require more maintenance.

8. 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 and by using a series of
tanks, withdraw from the last in series.
The stored rainwater may need to be
analyzed properly before use in a way
appropriate to ensure its safe use 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 may be
necessary, depending on how the water
will be used. Quality of harvested water

9. According to the extent to
which water is purified,
rainwater can replace
domestic functions in a
household.

10. 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. The water storage tank size should be large enough to contain
the captured water System setup.

11. Rooftops: If buildings with impervious
roofs are already in place, the
catchment area is effectively available
free of charge and they provide a supply
at the point of consumption.
Paved and unpaved
areas i.e., landscapes,
open fields, parks,
stormwater drains, roads
and pavements and
other open areas can be
effectively used to
harvest the runoff. The
main advantage in using
ground as collecting
surface is that water can
be collected from a
larger area. This is
particularly
advantageous in areas
of low rainfall.

12. Waterbodies: The potential of lakes, tanks and ponds to store rainwater is
immense. The harvested rainwater can not only be used to meet water
requirements of the city, it also recharges groundwater aquifers.
Stormwater drains: Most of the residential colonies have proper network of
stormwater drains. If maintained neatly, these offer a simple and cost effective
means for harvesting rainwater. From where to harvest rain 32

13. 1. Catchments
2. Collection gutters
3. Coarse mesh
4. Rain head inlet filter
5. First flush diverter
6. inlet screen
7. Collection cistern
8. Overflow port
9. Auto fill/ Automatic top up
mechanism
10.Pump
11.Water filter
12.Water level indicator

14. Catchments: The catchment of a water
harvesting system is the surface which
directly receives the rainfall and provides
water to the system. It can be a paved
area like a terrace or courtyard of a
building, or an unpaved area like a lawn
or open ground. A roof made of
reinforced cement concrete (RCC),
galvanised iron or corrugated sheets can
also be used for water harvesting.

15. 2. Coarse mesh at the roof to prevent the passage of
debris.
3. Gutters: Channels all around the edge of a sloping
roof to collect and transport rainwater to the storage
tank
4. Conduits- Conduits are pipelines or drains that
carry rainwater from the catchment or rooftop area to
the harvesting system. Conduits can be of any
material like polyvinyl chloride (PVC) or galvanized
iron (GI), materials that are commonly available.

16. 5. First-flushing: A first flush device is a valve that ensures that runoff from the
first spell of rain is flushed out and does not enter the system. This needs to be
done since the first spell of rain carries a relatively larger amount of pollutants
from the air.

17. 6. Filter The filter is used to remove suspended pollutants from rainwater
collected over roof. A filter unit is a chamber filled with filtering media such as
fibre, coarse sand and gravel layers to remove debris and dirt from water
before it enters the storage tank or recharges structure.
a. Charcoal water filter A simple charcoal filter can be made in a drum or an
earthen pot. The filter is made of gravel, sand and charcoal, all of which
are easily available.

18. b. Sand filters are easy and inexpensive to construct. These filters can be
employed for treatment of water to effectively remove turbidity (suspended
particles like silt and clay), colour and microorganisms. In a simple sand filter
that can be constructed domestically, the top layer comprises coarse sand
followed by a 5-10 mm layer of gravel followed by another 5-25 cm layer of
gravel and boulders.