An Report On Rain Water Harvesting

1. Acknowledgement
My heart pulsates with the thrill for tendering gratitude to those
persons who helped me in completion of the report.
The most pleasant point of presenting a thesis is the opportunity
to thank those who have contributed to it. Unfortunately, the list
of expressions of thank no matter how extensive is always
incomplete and inadequate. Indeed this page of acknowledgment
shall never be able to touch the horizon of generosity of those
who tendered their help to me.
I extend my deep sense of gratitude and indebtedness to our
guide Prof._________________________Department Of_____________________
, College, for their kind attitude, invaluable guidance, keen
interest, immense help, inspiration and encouragement which
helped us carrying out our present work.
It is a great pleasure for me to acknowledge and express my
gratitude to my classmates and friends for their understanding,
unstinted support and endless encouragement during completion
of this report. Lastly, I thank all those who are involved directly or
indirectly in completion of the present Report.

2. Preamble
It is high time now to fall for surface water usage instead of going
for ground water resources to meet human demand on needs.
Considered the main source of surface water, rainwater is
deemed more or less as fresh; the cost of collecting rainwater too
is very low. Rivers and canals, lakes and wetlands, ponds and
drywells – all are potential catchments to hold direct rainwater
and its indirect source, the run-off storm water. The closed tanks
also doubly work as settlement tanks to innately clearing the
contaminated water to some extent. Pebbles, gravels, sand and
charcoal – all available in abundance – work great as natural filter
for cleaning the rainwater before usage. Hence keeping an eye on
the rapidly increasing day-to-day demand for water among fast
growing human population, there lies a great opportunity to
harvest rainwater to meet a potential scarcity and avoid
destruction of the normal groundwater table level. The boon of
rainwater harvesting is – the unused or extra water which
remains after using by the human settlements – it can be send
down the aquifer to charge the groundwater level too.

3. Contents
 Introduction
 Reasons for rainwater harvesting
 Objectives of Rainwater Harvesting
 Methods of Rainwater Harvesting
 Advantages of Rainwater Harvesting
 Disadvantages of Rainwater Harvesting
 Harvesting can begin today
 Success stories of Rainwater harvesting in India
 References

4. Introduction
Water is our most precious natural resource and something that
most of us take for granted. We are now increasingly becoming
aware of the importance of water to our survival and its limited
supply, especially in such a dry places.
The harvesting of rainwater simply involves the collection of
water from surfaces on which rain falls, and subsequently storing
this water for later use. Normally water is collected from the
roofs of buildings and stored in rainwater tanks. Water can also
be collected in dams from rain falling on the ground and
producing runoff.
Harvesting Rainwater for saving drinking water has gained
enormously in significance as modern water saving sanitary
technique. This can be used for private and public buildings as
well as for many industrial areas. Beyond that rainwater
harvesting plays an important role for the rainwater (storm
water) management of housing estates. Due to the storage
(retention) and the usage of rainwater the water flowing off
housing estates in both reduced and delayed. Rainwater
harvesting is a system that is gaining speed over time. Areas that
experience high amounts of rainfall will benefit the most from the
system and will be able to distribute water to dry lands with ease.
However, the beneficial environmental impact of the system is
what drives it further as of now.

5. Reasons for rainwater harvesting: Why?
1. Increasing water needs/demands
The rapid rise in human population has made optimum use of
fresh water imperative.
Urban water supply systems in particular are under
tremendous pressure to meet the needs of the population as
well as industry and large-scale construction.
The increased need for water results in lower groundwater
tables and depleted reservoirs. Many piped water supply
systems fail.
Consumption of polluted water is beset with health hazards.
The use of rainwater is a useful alternative.
2. Variations in water availability
The availability of water from sources such as lakes, rivers and
shallow groundwater can fluctuate strongly.
Unchecked rainwater runoff is causing soil erosion.
Collecting and storing rainwater can provide water for
domestic use in periods of water shortage.
Rainwater may also provide a solution when the water quality
is low or varies during the rainy season in rivers and other
surface water resources (for example in Bangladesh).
3. Responsibilities towards protecting Nature
Using more of rainwater helps to conserve & augment the
storage of ground water
It helps to arrest sea water intrusion in coastal areas

6. It helps to avoid flood & water stagnation in urban areas
Reduces water and electricity bills
4. Advantage of collection and storage near the place of use
Traditional sources are located at some distance from the
community. Collecting and storing water close to households
improves the accessibility and convenience of water supplies
and has a positive impact on health.
It costs less to collect rainwater than to exploit groundwater.
Only traditional knowledge, skills and materials can be used to
collect the water and no government technical assistance is
required for repair and maintenance.
Collecting rainwater is the only way of recharging water
sources and revitalizing dry open wells and dry hand pumps.
It can also strengthen a sense of ownership. It gives an
opportunity for communities to come together and work
closer. It allows for the decentralized control and community
management of water.
It will provide productive employment to the rural poor in
their own villages.
5. Quality of water supplies
Water supplies can become polluted either through industrial
or human wastes or by intrusion of minerals such as arsenic,
salt (coastal area) or fluoride.
Rainwater is the ultimate fresh water.
Rainwater is generally of good quality.

7. Reasons for rainwater harvesting: When?
1. Rain water harvesting measures are essential when the ground
water is brackish or has a high Iron or Fluoride content.
2. Rain water harvesting measures should begin four months
before the monsoon is to arrive.
3. Concentrated water demand in urban areas for various
purposes like household, institutions (e.g. schools and colleges,
hospitals, offices, markets and shopping malls), factories, and
even water parks.

8. Objectives of Rainwater Harvesting
The main objectives of rainwater harvesting are:
1. To meet the increasing demand of water.
2. To reduce the run-off which chokes the drains.
3. To avoid the flooding of roads.
4. To raise the underground water table.
5. To reduce groundwater pollution.
6. To reduce soils erosion.
7. Supplement domestic water needs.

9. Methods and Techniques:
The methods of ground water recharge mainly are:
Urban Areas:
Roof top rain water/storm runoff harvesting through
1. Recharge Pit
2. Recharge Trench
3. Tubewell
4. Recharge Well
Rural Areas:
Rain water harvesting through
1. Gully Plug
2. Contour Bund
3. Gabion Structure
4. Percolation Tank
5. Check Dam/Cement Plug/Nala Bund
6. Recharge Shaft
7. Dugwell Recharge
8. Ground Water Dams/Subsurface Dyke

10. Various methods of rainwater harvesting are:-
1. Surface runoff harvesting
In urban area rainwater flows away as surface runoff. This runoff
could be caught and used for recharging aquifers by adopting
appropriate methods.
2. 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 ground water level of the area.
Components of the roof top rainwater harvesting

11. The illustrative design of the basic components of roof top
rainwater harvesting system is given in the typical schematic
diagram.
The system mainly constitutes of following sub components:
 Catchment
 Transportation
 First flush
 Filter

12. 1. Catchment: 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 rainwater to the
harvesting system.
2. 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 material.
3. 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.
4. 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 not 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 fro treatment of water to effectively
remove turbidity, colour and microorganisms. After first

13. flushing of rainfall, water should pass through filters. A gravel,
sand and ‘netlon’ mesh filter is designed and placed on top of
the storage tank. This filter is very important in keeping the
rainwater in the storage tank Clean. It removes silt, dust, leaves
and other organic matter from entering the storage tank. The
filter media should be cleaned daily after every rainfall event.
Clogged filters prevent rainwater from easily entering the
storage tank and the filter may overflow. The sand or gravel
media should be taken out and washed before it is replaced in
the filter.

14. Advantages of Rainwater Harvesting
1. Easy to Maintain:
Utilizing the rainwater harvesting system provides certain
advantages to the community. First of all, harvesting rainwater
allows us to better utilize an energy resource. It is important to
do so since drinking water is not easily renewable and it helps in
reducing wastage. Systems for the collection of rainwater are
based on simple technology.
The overall cost of their installation and operation is much lesser
than that of water purifying or pumping systems. Maintenance
requires little time and energy. The result is the collection of
water that can be used in substantial ways even without
purification.
2. Reducing Water Bills:
Water collected in the rainwater harvesting system can be put to
use for several non-drinking functions as well. For many families
and small businesses, this leads to a large reduction in their
utilities bill. On an industrial scale, harvesting rainwater can
provide the needed amounts of water for many operations to take
place smoothly without having to deplete the nearby water
sources.
It also lessens the burden of soil erosion in a number of areas,
allowing the land to thrive once again. In fact, it can also be stored
in cisterns for use during times when water supplies are at an all-
time low.

15. 3. Suitable for Irrigation:
As such, there is little requirement for building new
infrastructure for the rainwater harvesting system. Most rooftops
act as a workable catchments area, which can be linked to the
harvesting system. This also lessens the impact on the
environment by reducing use of fuel based machines.
Rainwater is free from many chemicals found in ground water,
making it suitable for irrigation and watering gardens. In fact,
storing large reservoirs of harvested water is a great idea for
areas where forest fires and bush fires are common during
summer months.
4. Reduces Demand on Ground Water:
With increase in population, the demand for water is also
continuously increasing. The end result is that many residential
colonies and industries are extracting ground water to fulfill their
daily demands. This has led to depletion of ground water which
has gone to significant low level in some areas where there is
huge water scarcity.
5. Reduces Floods and Soil Erosion:
During rainy season, rainwater is collected in large storage tanks
which also help in reducing floods in some low lying areas. Apart
from this, it also helps in reducing soil erosion and contamination
of surface water with pesticides and fertilizers from rainwater
run-off which results in cleaner lakes and ponds.

16. 6. Can be Used for Several Non-drinking Purposes:
Rainwater when collected can be used for several non-drinking
functions including flushing toilets, washing clothes, watering the
garden, washing cars etc. It is unnecessary to use pure drinking
water if all we need to use it for some other purpose rather than
drinking.

17. Disadvantages of Rainwater Harvesting
1. Unpredictable Rainfall:
Rainfall is hard to predict and sometimes little or no rainfall can
limit the supply of rainwater. It is not advisable to depend on
rainwater alone for all your water needs in areas where there is
limited rainfall. Rainwater harvesting is suitable in those areas
that receive plenty of rainfall.
2. Initial High Cost:
Depending on the system’s size and technology level, a rainwater
harvesting system is costly and benefit from it cannot be derived
until it is ready for use. Like solar panels, the cost can be
recovered in 10-15 years which again depends on the amount of
rainfall and sophistication of the system.
3. Regular Maintenance:
Rainwater harvesting systems require regular maintenance as
they may get prone to rodents, mosquitoes, algae growth, insects
and lizards. They can become as breeding grounds for many
animals if they are not properly maintained.
4. Certain Roof Types may Seep Chemicals or Animal
Droppings: Certain types of roofs may seep chemicals, insects,
dirt or animals droppings that can harm plants if it is used for
watering the plants.
5. Storage Limits:
The collection and storage facilities may also impose some kind of
restrictions as to how much rainwater you can use. During the

18. heavy downpour, the collection systems may not be able to hold
all rainwater which ends in going to to drains and rivers.
Harvesting can begin today
Rainwater harvesting is something that thousands of families
across the world participate in, and you could be the next to enjoy
the multitude of benefits offered with rainwater harvesting. It is
an easy, simple and worthwhile process, so it is only in your best
interest to take a look at rainwater harvesting and its benefits to
your home.

19. Success stories of Rainwater harvesting in India
 Bangalore developed a master plan for rainwater harvesting
for its Comprehensive Development Plan area for 1279
square Kilometre. The report suggested that upto 25% of
the city’s requirement by 2011 could be met through
rainwater harvesting and in the optimistic scenario that
592.90 million litres per day equivalent could be harvested
in the city. The Karnataka Watershed Development Project
(KAWAD) is addressing the water scarcity and is now trying
out different institutional mechanisms to identify the
appropriate approach for resolving water use conflicts.
 Chennai has made rainwater harvesting compulsory for all
building in the city, both old and new, and claims that 98%
of the buildings have complied with the requirements which
seek to wither store rainwater or to recharge it to the
underground aquifer.
 Action for Social Advancement (ASA), nongovernmental
organization based in Madhya Pradesh, worked with 42
tribal villages (nearly 25,000 people) with a land area of
nearly 20,000 hectares in Jobat, one of the sub-districts of
Jhabua district in Madhya Pradesh, and carried out
watershed work at the small river basin level. They focused
on Land development, Water resources development,
Agriculture intensification and diversification, as well as
tried building and promoting people’s institutions around
the natural resource interventions. As a result, the
subsurface flow of water has improved significantly,
indicated by the increased flows in the streams and rivers in

20. the entire basin. Hand pumps and dug wells have become
permanent, while many of the dry dugwells have been
revived. Evidence of increased base flow can be confirmed
by the fact that in last three years private investments have
been directed towards shallow dug-wells.
 Sukhomajri is a small hamlet (59 families in the 1975, and
89 in the 1990, census surveys) with average land holdings
of 0.57 ha, located in the Shiwalik foothills, India. An
integrated watershed development programme, with a
major emphasis on rain water harvesting, was planned here.
A six metre high earthen embankment pond with 1.8 ha-m
storage to harvest rainwater from a 4.2 ha catchment was
constructed in 1976. Crop yields were doubled as a result of
the use of supplementary irrigation water and improved
land management practises. Livestock water needs and
domestic water requirements were satisfied for all the
households.

21. References
en.wikipedia.org
studymafia.org
wwf.panda.org
cfpub.epa.gov
yourarticlelibrary.com
rainwaterharvesting.org