Rainwater harvesting is an important traditional practice in India that has declined with urbanization. It is needed now more than ever to address water shortages and declining groundwater levels. Roof rainwater harvesting systems collect rainwater and store it for use or allow it to percolate to recharge groundwater. Proper filtration is important to ensure water quality. Traditional methods like step wells and tanks helped conserve water and communities were responsible for maintenance. Reviving such systems with public participation can help address the water crisis through a decentralized approach.

1. CATCH RAIN
SAVE WATER
PPT-9
Green Earth Movement
An E-Newsletter for the cause of Environment, Peace, Harmony and Justice
Remember - “you and I can decide the future”

2. EVERY DROP MATTERS
Living creatures of the universe are
made of five basic elements, viz.,
Earth, Water, Fire, Air and Sky,
Obviously, water is one of the most
important elements and no creature can survive without
it. Despite having a great regard for water, we seem to
have failed to address this sector seriously. Human
being could not save and conserve water and it sources,
probably because of its availability in abundance. But
this irresponsible attitude resulted in deterioration of
water bodies with respect to quantity and quality both.
Now, situation has arrived when even a single drop of
water matters. However. " better late than never", we
have not realized the seriousness of this issue and

3. WHY RAIN WATER HARVESTING
In the present scenario management and distribution of
water has become centralized. People depend on
government system, which has resulted in disruption of
community participation in water management and
collapse of traditional water harvesting system.
As the water crisis continues to become
severe, there is a dire need of reform in
water management system and revival
of traditional systems. Scientific and
technological studies needs to be
carried out to assess present status so as to suggest
suitable mitigative measures for the revival to traditional
system/wisdom. Revival process should necessarily be
backed by people's initiative and active public participation.

4. TRADITIONAL METHOD – TIME-TESTED WISDOM
System of collection rainwater and
conserving for future needs has
traditionally been practiced in India.
The traditional systems were
time-tested wisdom of not only
appropriate technology of Rainwater
Harvesting, but also water management systems,
where conservation of water was the prime concern.
Traditional water harvesting systems were Bawaries,
step wells, jhiries, lakes, tanks etc. These were the water
storage bodies to domestic and irrigation demands.
People were themselves responsible for maintenance to
water sources and optimal use of water that could fulfill
their needs.

5. URBANIZATION HAS CAUSED DEPLETING GROUND WATER
LEVEL
The term rainwater harvesting is being frequently used these
days, however, the concept of water harvesting is not new for
India. Water harvesting techniques had been evolved and
developed centuries ago.
Ground water resource gets naturally
recharged through percolation. But due
to indiscriminate development and rapid
urbanization, exposed surface for soil has
been reduced drastically with resultant
reduction in percolation of rainwater,
thereby depleting ground water resource. Rainwater harvesting is
the process of augmenting the natural filtration of rainwater in to
the underground formation by some artificial methods. "Conscious
collection and storage of rainwater to cater to demands of water,
for drinking, domestic purpose & irrigation is termed as Rainwater

6. REASONS FOR HARVESTING RAINWATER
This is perhaps one of the most
frequently asked question, as to
why one should harvest rainwater.
There are many reasons but
Following are some of the
important ones.
•To arrest ground water 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

7. HOW TO HARVEST RAINWATER
Broadly there are two ways of
harvesting rainwater
(i) Surface runoff
havesting
(ii) Roof top
rainwater harvesting

8. SURFACE
RUNOFF
HARVESTING
In urban area
rainwater flows
away as surface
runoff. This runoff
could be caught
and used for
recharging aquifers
by adopting
ROOF TOP RAINWATER
HARVESTING
It is a system of catching
rainwater where it falls. In
rooftop harvesting, the roof
becomes the catchments,
and the rainwater is collected
from the roof of the
house/building. It can either
be stored in a tank or
diverted to artificial recharge
system. This method is less
expensive and very effective
and if implemented properly
helps in augmenting the

9. COMPONENTS OF THE ROOF TOP RAINWATER
HARVESTING SYSTEM
The illustrative design of the basic components of roof top
rainwater harvesting system is given in the following typical
schematic diagram/
The system mainly constitutes of following sub
components:
§ Catchment
§ Transportation
§ First flush
§ Filter
The surface that receives rainfall directly is the
catchment of rainwater harvesting system. It
may be terrace, courtyard, or paved or unpaved open ground.
The terrace may be flat RCC/stone roof or sloping roof.
Therefore the catchment is the area, which actually contributes

10. TRANSPORTATION
Rainwater from rooftop
should be carried through
down take water pipes or
drains to storage/harvesting
system. Water pipes should be
UV Resistant (ISI HDPE/PVC pipes) of
required
capacity. Water from sloping roofs
could be caught through gutters and down
take pipe. At terraces, mouth of the each drain
should have wire mesh to restrict floating

11. FIRST FLUSH
First flush is a device used to
flush off the water received in
First shower. The first shower
of rains needs to be flushed-off
to avoid contaminating
storable/rechargeable water by
the probable contaminants of the atmosphere and
the catchment roof. It will also help in cleaning of silt
and other material deposited on roof during dry
seasons. Provisions of first rain separator should be
made at outlet of each drainpipe.

12. FILTER There is always some skepticism
regarding Roof Top Rainwater
Harvesting since doubts are raised that
rainwater may contaminate
groundwater. There is remote
possibility of this fear coming true if
proper filter mechanism is adopted.
Secondly all care must be taken to see
that underground sewer drains are not
punctured and no leakage is taking
place in close vicinity. Filters are used
for treatment of water to effectively
remove turbidity, colour and
microorganisms. After first flushing of
rainfall, water should pass through
filters. There are different types of

13. TYPES OF FILTERS USED FOR RAIN WATER
HARVESTING
1. Sand Gravel Filter
These are commonly used filters, constructed by brick
masonry and filleted by pebbles, gravel, and sand as
shown in the figure. Each layer should be separated by
wire mesh.

14. 2. Charcoal Filter
Charcoal filter can be
Made in-situ or in a
drum. Pebbles, gravel,
sand and charcoal as
shown in the figure
should fill the drum or chamber. Each layer
should be separated by wire mesh. Thin
layer of charcoal is used to absorb odor if
any.

15. 3. PVC- Pipe filter
This filter can be made by PVC pipe of 1 to 1.20 m
length; Diameter of pipe depends on the area of roof. Six
inches dia. pipe is enough for a 1500 Sq. Ft. roof
and 8 inches dia. pipe should be used
for roofs more then 1500 Sq. Ft. Pipe
is divided into three compartments
by wire mesh. Each component
should be filled with gravel and
sand alternatively as shown in the
figure. A layer of charcoal could also be inserted
between two layers. Both ends of filter should have
reduce of required size to connect inlet and outlet. This
filter could be placed horizontally or vertically in the
system.

16. 4. Sponge Filter
It is a simple filter made from PVC
drum having a layer of sponge in the
middle of drum. It is the easiest and
cheapest form filter, suitable for
residential units.

17. METHODS OF ROOF TOP RAINWATER HARVESTING
1. Storage of Direct use
In this method, rain water collected from the roof of the building is
diverted to a storage tank. The storage tank has to be designed
according to the water requirements, rainfall and catchment
availability. Each drainpipe should have mesh filter at mouth and first
flush device followed by filtration system before connecting to the
storage tank. It is advisable that each tank should have excess water
over flow system.
Excess water could be diverted to recharge system. Water from
storage tank can be used for secondary purposes such as washing
and gardening etc. This is the most cost effective way of rainwater
harvesting. The main advantage of collecting and using the rainwater
during rainy season is not only to save water from conventional
sources, but also to save energy incurred on transportation and
distribution of water at the doorstep. This also conserve groundwater,

18. 2. RECHARGING GROUND WATER AQUIFERS
Ground water aquifers can be recharged by various
kinds of structures to ensure percolation of rainwater
in the ground instead of draining away from the
surface. commonly used recharging
methods are:-
a) Recharging of bore wells
b) Recharging of dug wells.
c) Recharge pits
d) Recharge Trenches
e) Soak ways or Recharge Shafts
f) Percolation Tanks

19. 2a] RECHARGING OF BORE WELLS
Rainwater collected from rooftop of the building is diverted
through drainpipes to settlement or filtration tank. After settlement
filtered water is diverted to bore wells to recharge deep aquifers.
Abandoned bore wells can also be used for recharge.
Optimum capacity of settlement
tank/filtration tank can be designed on the
basis of area of catchment, intensity of
rainfall and recharge rate as discussed in
design parameters. While recharging, entry
of floating matter and silt should be
restricted because it may clog the recharge
structure. "first one or two shower should be flushed out
through rain separator to avoid contamination. This is very
important, and all care should be taken to ensure that this has
been done.”

20. 2b] RECHARGING OF DUG WELLS
Dug well can be used as recharge structure.
Rainwater from the rooftop is diverted to dug
wells after passing it through filtration bed.
Cleaning and desalting of dug well should be
done regularly to enhance the recharge rate. The
filtration method suggested for bore well
recharging could be used.

21. 2c] RECHARGE PITS
Recharge pits are small pits of any shape
rectangular, square or circular, contracted with
brick or stone masonry wall with weep hole at
regular intervals. Top of pit can be covered with
perforated covers. Bottom of pit should be filled
with filter media.
The capacity of the pit can be designed on the
basis of catchment area, rainfall intensity and
recharge rate of soil. Usually the dimensions of
the pit may be of 1 to 2 m width and 2 to 3 m
deep depending on the depth of pervious strata.

22. 2d] RECHARGE TRENCHES
Recharge trench in provided where
upper impervious layer of soil is
shallow. It is a trench excavated on
the ground and refilled with porous
media like pebbles, boulder or
brickbats. it is usually made for
harvesting the surface runoff. Bore wells can also be
provided inside the trench as recharge shafts to
enhance percolation. The length of the trench is decided
as per the amount of runoff expected. This method is
suitable for small houses, playgrounds, parks and
roadside drains. The recharge trench can be of size 0.50
to 1.0 m wide and 1.0 to 1.5 m deep.

23. 2e] SOAK AWAY OR RECHARGE SHAFTS
Soak away or recharge shafts are provided where
upper layer of soil is alluvial or less pervious.
These are bored hole of 30 cm dia. up to 10 to 15
m deep, depending on depth of pervious layer.
Bore should be lined with slotted/perforated
PVC/MS pipe to prevent collapse of the vertical
sides. At the top of soak away required
size sump is constructed to
retain runoff before the filters
through soak away. Sump
should be filled with filter media.

24. 2f] PERCOLATION TANKS
Percolation tanks are artificially created surface water
bodies, submerging a land area with adequate
permeability to facilitate sufficient percolation
to recharge the ground water.
These can be built in big
campuses where land is
available and topography is
suitable.
Surface run-off and roof top water can be diverted to this
tank. Water accumulating in the tank percolates in the
solid to augment the ground water. The stored water can
be used directly for gardening and raw use. Percolation
tanks should be built in gardens, open spaces and
roadside green belts of urban area.

25. DO'S AND DON’TS
Harvested rainwater is used for direct usage or for
recharging aquifers. It is most important to ensure that
the rainwater caught is free from pollutants. Following
precautionary measures should be taken while
harvesting rainwater:-
Roof or terraces uses for harvesting should be clean, free from
dust, algal plants etc.
Roof should not be painted since most paints contain toxic
substances and may peel off.
Do not store chemicals, rusting iron, manure or detergent on the
roof.
Nesting of birds on the roof should be prevented.
Terraces should not be used for toilets either by human beings or
by pets.
Provide gratings at mouth of each drainpipe on terraces to trap

26. DO'S AND DON’TS
Provision of first rain separator should be made to flush off first
rains.
Do not use polluted water to recharge ground water.
Ground water should only be recharged by rainwater.
Before recharging, suitable arrangements of filtering should be
provided.
Filter media should be cleaned before every monsoon season.
During rainy season, the whole system (roof catchment, pipes,
screens, first flush, filters, tanks) should be checked before and after
each rain and preferably cleaned after every dry period exceeding a
month.
At the end of the dry season and just before the first shower of
rain is anticipated, the storage tank should be scrubbed and flushed
off all sediments and debris
Next slide
RAIN WATER HARVESTING CONSULTANTS

27. SOME OF THE WATER HARVESTING CONSULTANTS IN INDIA
(courtesy internet – list not exhaustive)
AHAMADABAD
Shakti Enterprises, Ahmadabad, Phone: +(91)-(79)-25834511,Mobile / Cell Phone: +(91)-9825957882 / 9426861544
BANGALORE
Greenspace Landscape India Private Limited: Bengaluru, Phone: +(91)-(80)-41531371, Mobile / Cell Phone: +(91)-
9886769245 / 9945744846
CHENNAI
Everest Associates, Chennai, Phone: +(91)-(44)-39163774, Mobile / Cell Phone: +(91)-9841216732
MUMBAI/NAVI MUMBAI
Pollucon Enviro Engineers Pvt Ltd: Borivali East,Mumbai, Phone: +(91)-(22)-28090134 Fax: +(91)-(22)-28090134, Mobile /
Cell Phone: +(91)-9619313351 / 9892104092
Natural Solutions, Dombivli East, Maharashtra; Phone: +(91)-(251)-2881173 Fax: +(91)-(251)-2440603, Mobile / Cell
Phone: +(91)-9870423023 / 9773030622
Techno Plast, Kandivali, Maharastra, Phone: +(91)-(22)-28646892 Fax: +(91)-(22)-28646892, Mobile / Cell Phone: +(91)-
9820233153 / 9004333153
Green Smile, Navi Mumbai, Phone: +(91)-(22)-65611443, Mobile / Cell Phone: +(91)-9004086256 / 9960334431
KERALA
Agro Machinery, Kochi, Phone: +(91)-(484)-2532586 Fax: +(91)-(11)-43852586, Mobile / Cell Phone: +(91)-9249444586 /
9446926387 / 8714504644
NEW DELHI
Rainbow Super Polymers, New Delhi, Phone: +(91)-(11)-22163898, Mobile / Cell Phone: +(91)-9810380604 / 9311623935
Richa Environmental Services Pvt Ltd, New Delhi, Fax: +(91)-(11)-43851403, Mobile / Cell Phone: +(91)-9711432204 /
7838084868
PUNE
Samartha Greentech, Pune, Phone: +(91)-(20)-25389898, Mobile / Cell Phone: +(91)-9822001692
Era Hydro- Biotech Energy Pvt. Ltd., Pune Phone: +(91)-(20)-25887303, Mobile / Cell Phone: +(91)-9422078412 /
8928698996 / 8928698997

28. This educational PowerPoint Presentation (editable) is
prepared by GEM Team (courtesy: internet).
For other similar GEM PowerPoint Presentations on
various environmental issues see next slide.
These PPTs may be downloaded from our website
www.infantjesusjogeshwari.in
The GEM PPTs can be creatively used for various
groups like school/college students, NGOs,
government officials, Church groups, SCC groups,
housing society members and so on.

29. 1. Twenty Simple Tips
2. Solar Energy
3. Junk Food
4. Plastic – a boon or bane?
5. Green Passion
6. Zero Garbage
7. Soft drink – A Health Hazard
8. Waste to energy
9. Rain Water Harvesting
10. Eco-friendly Religions
11. Happy Green Diwali
12. Climate Change
13. The future of Biodiversity
14. Genetically Modified Foods
15. Waste Water Treatment
16. Body, Organ, Tissue Donation
17. Organic Farming
18. Waste to cooking gas
19. Reduce, Reuse, Recycle
20. Protect Mangroves
21. Say NO to Bottled water
22. Save Lakes and Ponds
23. Forests are green lungs
24. Coal Mining and Ecology
25. Sin of Food Waste
26. Climate change and Poverty
27. Stop Water Pollution
28. Carbon Footprints
29. Parks and Open Spaces
30. Rising Sea Levels
31. Laudato Si – Pope’s Encyclical
32. Air Pollution
33. Life Style Changes
34. Laudato Si – Fr Gerard
35. Water Pollution
36. Sand Mining
37. Kids Eco Clubs
38. Water Disaster

30. For Free GEM E-Newsletters visit –
www.infantjesusjogeshwari.in
Go to GEM section,
click GEM E-NEWSLETTERS