GOVERNMENT POLYTECHNIC, JAGATSINGHPUR

DEPARTMENT OF CIVIL ENGINEERING

A PROJECT REPORT ON

Rainwater Harvesting

Submitted in partial fulfilment for the degree of Diploma in Civil engineering

Under the guidance of

Mr. Swastik Pradhan ( Lect. )
Mrs. Amarpalli Sahoo ( HOD )
Group members
1. Purna Chandra mohapatra (F22158001031)
2. Shakti swaraj bhuyan (F22158001044)
3. Shuvam behera (F22158001045)
4. Smrutirekha samal (f22158001048)
5. Soumya ranjan parida (F22158001050)
6. Suman sahoo (L23158001018)

[1]
7.
8.

[2]
 Certificate
This is to certify that the project entitled “ ------------------- “ by the group
members has been carried out under supervision in partial fulfillment of the
requirements for the Diploma in Civil Engineering branch during session (2024-25)
in Civil Engineering department of Government Polytechnic Jagatsinghpur and the
work is the original work of the team

[3]
 ABSTRACT
At the rate in which Indian population is expanding, it is said that India
will definitely supplant China from its number | position of most thickly
populated nation of the world after 20-30. These will prompt high rate
of utilization of most profitable regular asset: Water's subsequent in
enlargement of weights on the allowed freshwater assets. Old technique
for damming waterway and transporting water to urban zone has its own
issues of everlasting inconveniences of social and political. Keeping in
mind the end goal to save and take care of our day-by-day demand of
water prerequisite, we have to think for elective savvy and generally
less demanding mechanical techniques for monitoring water. Rainwater
harvesting is a technique satisfying those necessities.
This project mainly deals with different methods of rainwater harvesting
and different components of traditional methods that were adopted by
ancestors. Preventive measures, advantages, and disadvantages of
rainwater harvesting are also being included in this project. It also
comprehended how to do rainwater harvesting via solar panels? And a
case study is being included for a better understanding of rainwater
harvesting,

[4]
 TABLE OF CONTENTS
CHAPTER NAME
NO.
ACKNOWLBDORMENT:
ABSTRACT:
LIST OF FIOURES:
TABER OF CONTENT:
1. INTRODUCTION:
2. RAINWATER HARVESTING:
2.1 NEED FOR RAINWATER HARVESTING
2.2 ADVANTAGES AND DISADVANTAGES
2.3 APPLICATIONS
2.3.1) DOMESTIC USE
2.3.2) AGRICULTURE USE
2.3.3) FINDUSTRIAL USE
2.4 RAINWATER HARVESTING COMPONENTS
3. METHODS OF RAINWATER HARVESTING
3:1 GROUNDWATER HARVESTING:
3.1.1 USE OF GROUND WATER HARVESTING
3.1.2 METHODS OF GROUND WATER FILLING
3.1.3 FACTORS AFFECTING GROUND WATER FILLING
3.2 ROOF TOP RAINWATER HARVESTING.

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 3.2.1 ADVANTAGES

3.2.2 DISADVANTAGES

3.3 SURFACE RUNOFF HARVESTING

3.3.1 ADAVANTAGES

3.3.2 DISADVATAGES

3.4 TRADITIONAL METHODS OF RAINWATER HARVESTING

3.5 MODERN METHODS OF RAINWATER HARVESTING
3.6 TYPES OF RAINWATER HARVESTING IN INDIA
3.7 RAINWATER HARVESTING BY FRESH WATER
3.8 RAINWATER HARVESTING BY SOLAR POWERPANELS
CASE STUDY
CONCLUSION BIBLIOGRAPHY

…………….<>………….

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 LIST OF FIGURES
FIGURE NO. TITTLE

2.01 RAINWATER HARVESTING SYSTEM

2.4.1 RAINWATER HARVESTING COMPONENTS
2.1 ROOFTOP RAINWATER HARVESTING
3.4.1 TRADITIONAL METHOD
3.4.2 SAZA KUVA
3.4.3 GROUND WATER DAM
3.4.4 FERROW CEMENT TANK
(1) AREA OF TERRACE
(2) ROOF AREA
(3) SET UPS PROPOSED
(4) RECHARGE PIT

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 1. INTRODUCTION
Millions of people throughout the world do not have access to clean water for domestic
purposes, In many parts of the world conventional piped water is either absent,
unreliable or too expensive. One of the biggest challenges of the 21st century is to
overcome the growing water shortage. Rainwater harvesting has thus regained its
importance as a valuable alternative or supplementary water resource, along with
more conventional water supply technologies. Much actual or potential water
shortages can be relieved if rainwater harvesting is practiced more widely. People
collect and store rainwater in buckets, tanks, ponds and wells. This is commonly
referred to as rainwater harvesting and has been practiced forcenturies. Rainwater
can be used for multiple purposes ranging from irrigating crops to washing, cooking
and drinking.
In many areas rain water harvesting has now been introduced as part of an integrated
water supply, where the town water supply is unreliable, or where local water
sources dry up for a part of the year. But rain water harvesting can also be introduced
as the sole water source for communities or households. The technology is flexible
and adaptable to a very wide variety of conditions. It is used in the richest and the
poorest societies, as well as in the wettest and the driest regions on our planet. It
strives to give practical guidance for households, CBOs, NGOs, local government
staff and extension workers in designing and applying the right systems, methods and
techniques for harvesting rainwater on a small scale (varying from 500-60,000 liters).
It explains the principles and components of a rooftop rainwater system for collecting
and storing rainwater.
It also strives to guide the process of planning, designing and actual construction.
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 2. RAIN
WATER
HARVESTING
Rainwater harvesting, as shown in fig
2.01, is collecting the run-off from a
structure or
other impervious surface in order to store it for later use. Traditionally, this involves
harvesting the rain from a roof. The rain will collect in gutters that channel the water
into downspouts and then into some sort of storage vessel. Rainwater collection
systems can be as simple as collecting rain in a rain barrel or as claborate as
harvesting rainwater into large cisterns to supply your entire household demand. The
idea of rainwater harvesting usually conjures up images of an old fam cistern or
thoughts of developing countries. Fig 2.01 Rain water harvesting system the reality
is that rainwater harvesting is becoming a viable alternative for supplying our
households and businesses with water. It's not just for the farm any more! There are
many countries such as Germany and Australia where rainwater harvesting is a norm.
Due to the green building movement, you will be seeing rainwater harvesting
systems become more popular in America,
The collection of rainwater is known by many names throughout the world. It ranges
from rainwater collection to rainwater harvesting to rainwater catchment. In addition,
terms such as roof water collection or rooftop water collection is also used in other
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countries. We believe that rainwater harvesting is a viable technology in an urban
setting. All that is necessary to take advantage of this resource is to capture the free

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water falling on your roof and direct it to a rainwater storage tank. By doing this, you
can take control of your water supply and replace all or at least a substantial portion
of your water needs. Rainwater harvesting systems can be configured to supply your
whole house and your landscape needs.
2.1 NEED FOR RAIN WATER HARVESTING
The rapid rise in human population has made optimum use of fresh water imperative.
Urban water supply systems in particular area 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. 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. Using more of rainwater helps to conserve & augment
the storage of ground water. It helps to arrest sea water intrusion in coastal areas. It
helps to avoid flood & water stagnation in urban areas Reduces water and electricity
bills.

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.

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2.2. Advantages
 Lesscost
 Helps in reducing the water bill.
 Decreases the demand for water.
 Reduces the need for imported water.
 Promotes both water and energy conservation.
 Improves the quality and quantity of groundwater.
 Does not require a filtration system for landscape irrigation.
 This technology is relatively simple, easy to install and operate.
 It reduces soil erosion, storm water runoff, flooding, and pollution of
surface water with fertilizers, pesticides, metals and other sediments.

 It is an excellent source of water for landscape irrigation with no

chemicals and dissolved salts and free fromall minerals.

Disadvantages
 Regular Maintenance is required.
 Requires some technical skills for installation.
 Limited and no rainfall can limit the supply of Rainwater.
 If not installed correctly, it may attract mosquitoes and other
waterborne diseases.
 One of the significant drawbacks of the rainwater harvesting system is
storage limits,

2.3 APPLICATIONS
2.3.1 DOMESTIC USE
Rainwater harvesting is an effective and ecofriendly method of reducing water usage
in your home, which will lead to reduced water charges. Switching to an ecofriendly
rainwater harvesting system is neither complicated or time consuming and will result
in a wide range of benefits for your home. Our rainwater harvesting systems can help
home owners save from 50% - 80% of their main water usage. As with our
commercial systems, domestic rainwater harvesting systems are available in two
types of systems, direct and in-direct. With a direct system, the harvested water is
pumped directly to the
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appliances and with an in-direct system, the harvested water is pumped to a holding
tank or header tank and gravity feeds the appliances.

We have a wide range of tanks to suit any application. We supply both under-ground
and over-ground tanks, where they are one-piece tanks or a series of small tanks to fit
into areas with limited space. Please refer to our Brochure to learn more about our
underground & over ground range. The harvested water can be used for a number of
appliances such as toilets, washing machines, showers, sinks, baths and gardening.

2.3.2 AGRICULTURAL USE

In regards to urban agriculture, rainwater harvesting in urban areas reduces the
impact of runoffand flooding. The combination of urban ‘green’ rooftops with
rainwater catchments has been found to reduce building temperatures by more than
1.3 degrees Celsius. Rainwater harvesting in conjunction with urban agriculture
would be a viable way to help meet the United Nations Sustainable Development
Goals for cleaner and sustainable cities, health and wellbeing, and food and water
security, The technology is available; however, it needs to be remodeled in order to
use water more efficiently, especially in an urban setting.

Many countries, especially those with arid environments, use rainwater harvesting as
a cheap and reliable source of clean water. To enhance irrigation in arid
environments, ridges of soil are constructed to trap and prevent rainwater from
running down hills and slopes. Even in periods of low rainfall, enough water is
collection for crops to grow. Water can be collected from roofs, dams and ponds can
be constructed to hold large quantities of rainwater so that even on days when little to
no rainfall occurs, enough is available to irrigate crops.

2.3.3 INDUSTRIAL USE

The various processes of a factory or industry make a generous use of water
resource. Some industries like power generation, textiles and garments, beverage,
ete. Make more use of water than their other counterparts. Along with using water for

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production

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work, the offices and factories also need to provide enough water for the sanitation
and drinking purposes, to their hundreds of employees. Since the main water source
can provide the limited amount, these industries and offices must rely upon the
alternate source of harnessing water, i.e., rainwater harvesting.

Industrial and other public or private commercial buildings report an excessive use of
water. For some businesses or industries, water is a major raw material, needed for
production and manufacturing of finished business products. For example, car wash
businesses, irrigation, refueling areas, construction sites, etc. For fulfilling such a
high demand for water, the installation of a rainwater harvesting system is strongly
advocated (and legally mandated in some Indian states) in different types of
industrial and office buildings.

2.4 RAIN WATER HARVESTING COMPONENTS

Irrespective of the complexity, rainwater harvesting systems will have the following
five basic components as shown in figure 2.4.1

1. Catchment: the surface from which rainwater is collected for storage. This could
be a rooftop, a paved flooring surface or a landscaped area, Catchment area is the
area of that surface, usually calculated in square meters.
2. Gutters and Down take pipes: lead the water from the catchment surface to the
storage tank.
3. Filters and first flush devices: remove grit, leaves and dirt that the rainwater may
transport from the catchment, before the water enters the storage tank. When it
rains after a long gap. the rooftops are usually very dirty and the rainwater also
carries
with it a lot of dissolved air pollutants, A first flush device diverts the water from
the first rain so that it does not enter the storage tank.
4. Storage tanks: These can be above the ground or below the ground.

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5. Delivery systems: Piping systems that convey the stored rainwater till the point of
end-us.

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 Fig 2.4.1 RAIN WATER HARVESTING COMPONENTS

3. METHODS OF RAINWATER HARVESTING SYSTEM

Rainwater harvesting is the collection and
storage of rainwater for reuse on- site,
rather than allowing it to run off. These
stored waters are used for various
purposes such as gardening, irrigation
etc. Various methods of rainwater
harvesting are described in this section.

1 Surface runoff harvesting

In urban area rainwater flows away as
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surface runoff. This runoff could be
caught and used for recharging aquifers
by adopting appropriate methods. Fig2.1 Rooftop rainwater harvesting

2 Rooftop 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 groundwater level of the area. The roof top rain
water harvesting system is shown in figure 2:1.

3.1 GROUNDWATER HARVESTING

Groundwater is the water present beneath Earth's surface in rock and soil pore spaces
and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is
called an aquifer when it can yield a usable quantity of water. The depth at which soil
pore spaces or fractures and voids in rock become completely saturated with water is
called the water table. Typically, groundwater is thought of as water flowing through
shallow aquifers, but, in the technical sense, it can also contain soil moisture,
permafrost, immobile water in very low permeability bedrock, and deep geothermal
or oil formation water. Groundwater is hypothesized to provide lubrication that can
possibly influence the movement of faults. Itis likely that much of Earth's subsurface
contain some water, which may be mixed with other fluids in some instances.

3.1.1 USES OF GROUNDWATER HARVESTING

Fresh groundwater was used for many important purposes, with the largest amount
going toward irrigating crops. Local city and county water departments withdraw a
lot of groundwater for public uses, such as for delivery to homes, businesses, and
industries, as well as for community uses such as firefighting, water services at
public buildings, and for keeping local residents happy by keeping community
swimming pools full of water. Industries and mining facilities also used a lot of
groundwater. The majority of water used for self-supplied domestic and livestock
purposes came from groundwater sources. For the environment groundwater plays a
very important role in keeping the water level and flow into rivers, lakes and
wetlands, Specially during the drier months when there is little direct recharge
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from rainfall, it provides the

[19]
environment with groundwater flow through the bottom of these water bodies and
becomes essential for the wild life and plants living in this environment.
Groundwater also plays a very relevant role in sustain navigation through inland
waters in the drier seasons. By discharging groundwater into the rivers, it helps
keeping the water levels higher.
Groundwater is found almost everywhere and its quality is usually very good. The
fact that groundwater is stored in the layers beneath the surface, and sometime at
very high depths, helps protecting it from contamination and preserve its quality,
Additionally, groundwater is & natural resource which can often be found close to
the final consumers and therefore does not require large investments in terms of
infrastructure and treatment, as it often is necessary when harvesting surface water.
The most important about using groundwater is to find the right balance between
withdrawing and letting the aquifers level recover to avoid overexploitation and to
avoid pollution of this crucial resource.

3.1.2 METHODS OF GROUND WATER HARVESTING

I) Recharging of bore holes
11) Recharging through wells
111) Recharging through pits
IV) Recharging through trenches
V) Recharging through shafts
VI) Recharging making percolation tanks

3.1.3 FACTORS EFFECTING GROUND WATER FILLING

Climate
The future of climate change introduces the opportunity of implications regarding the
availability of groundwater recharge for future drainage basin. Groundwater recharge
rates will have the smallest impact on a climate of equal humidity and dryness. The
depletion of groundwater is evidence of the water table's response 10 excessive
pumping. Severe consequences of groundwater depletion include lowering of the
water
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table and depleting water quality. The quantity of water in the water table can change
rapidly depending on the rate of extraction. As the level of water decreases in the
aquifer, there is less available water to be pumped. If the rate of potential
groundwater recharge is less than the rate of extraction, the water table will be too
low for access. A consequence of this includes drilling deeper into the water table to
access more water. Drilling into the aquifer can be a costly endeavor and it is not
guaranteed that the quantity of available water will be exact to previous yields.

Urbanization
Further implications of groundwater recharge are a consequence of urbanization.
Road networks and infrastructure within cities prevents surface water from
percolating into the soil, resulting in most surface runoff entering storm drains for
local water supply. As urban development continues to spread across various regions,
rates of groundwater recharge will increase relative to the existing rates of the
previous rural region. The ecosystem will have to adjust to the clevated groundwater
surplus due to groundwater recharge rates, Additionally, road networks are less
permeable compared to soil, resulting in higher amounts of surface runoff. Therefore,
urbanization increases the rate of groundwater recharge and reduces infiltration,
resulting in flash floods as the local ecosystem accommodates changes to the
surrounding environment.

3.2 ROOF TOP RAIN WATER HARVESTING

Rooftop Rain Water Harvesting is the technique through which rain water is captured
from the roof catchments and stored in reservoirs. Harvested rain water can be stored
in sub-surface ground water reservoir by adopting artificial recharge techniques to
meet the household needs through storage in tanks. The Main Objective of rooftop
rain water harvesting is to make water available for future use. Capturing and storing
rain water for use is particularly important in dry land, hilly, urban and coastal areas.
In alluvial areas energy saving for Im. rise in ground water level is around 0.40 kilo
watt per hour.

3.2.1 ADVANTAGES OF ROOF TOP RAIN WATER HARVESTING

1. The rain water collected on rooftops is used to improve the vegetation cover on
ground.
2. With the growth of vegetation, the water seeps into the ground and replenishes the
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groundwater supply.

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 3. There is no run off by muddy or dirty water into the drains.

3.2.2 DISADVANTAGES OF ROOF TOP RAIN

WATER HARVESTING
1. People may use the store water for washing, sanitation or for industrial purpose. It
will flow into the drains, instead of soaking into the ground and will not promote
groundwater replenishment.
2. If scientific measure is not adopted for using rainwater for drinking, it may cause
harm to the people's health than tap water.

3.3 SURFACE RUNOFF HARVESTING

Surface runoff water harvesting is the collection, accumulation, treatment or
purification, and storing of storm water for its eventual reuse. It can also include
other catchment areas from manmade surfaces, such as roads, or other urban
environments such as parks, gardens and playing fields. Surface runoff water is an
excellent alternative to using mains drinking water for many purposes. If properly
designed, Surface runoff catchment systems can collect large quantities of rainwater.
The main challenge Surface runoff water harvesting poses is the removal of
pollutants in order to make this water available for reuse. Small reservoirs with
earthen bunds or embankments to contain runoffor river flow are built from soil
excavated from within the reservoir to increase storage capacity and a spillway or
weir allows controlled overflow when storage capacity is exceeded.

3.3.1 ADVANTAGES OF SURFACE RUNOFF RAIN

WATER HARVESTING
 Easy to Maintain
 Independent Water Supply
 Reducing Water Bills
 Suitable for Irrigation
 Reduces Demand on Ground Water
 Supplemental in Drought
 Reduces Floods and Soil Erosion
 Several Non-drinking Purposes
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 3.3.2 DISADVANTAGES OF SURFACE RUNOFF
RAIN WATER HARVESTING
 Unpredictable Rainfall
 Initial High Cost
 Regular Maintenance
 Storage Limits

3.4 TRADITIONAL METHODS OF RAIN

WATER HARVESTING
Water has been harvested in India since antiquity, with our ancestors perfecting the art
of water management. Many water harvesting structures and water conveyance
systems specific to the eco-regions and culture has been developed. Figure 3.4.1
shows a particular Traditional rainwater harvesting system.
 They harvested the rain drop directly. From rooftops, they collected water and
stored it in tanks built in their courtyards. From open community lands, they
collected the rain and stored it in artificial wells.
 They harvested monsoon runoff by
capturing water from swollen
streams during the monsoon
season and stored it harvesting
system various forms of water
bodies. Fig 3.4.1 Traditional
rainwater
 They harvested water from flooded
rivers.

SAZA KUVA

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An open well with multiple owners, saza kuva is the most important source of irrigation
in the Aravalli hills in Mewar,
eastern Rajasthan, The soil dug out to make the
well pit is used to construct a huge circular
foundation or an elevated platform sloping
away from the well. The figure of a saza kuva
is shown in figure 3.4.2. The first is built to
accommodate the rehat, a traditional water
lifting device: the sloping platform is for the
chada, in which buffaloes are used to lift
water.

PAT
The diversion bunds across the stream are made by piling up stones and then lining
negotiate small nullahs that join the stream off and on, and also sheer cliffs before
reaching the fields. The villagers irrigate their fields by ms. The channel requires
constant maintenance and it is the duty of the family irrigating the fields on a
particular day to take care of the pat on that particular day, It takes about two weeks
to get the pat flowing and the winter crop is sown in early November.

3.5 MODERN METHODS OF RAIN WATER HARVESTING

 Ground water Dams:

 The basic principle of

the groundwater dam
shown in figure 3.4.3
is that instead of
storing the water in
surface reservoirs,
water is stored
underground.
 The main advantages
of water storage in
groundwater dams
are that evaporation
Fig 3.4.3 Ground
water dam

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 losses are much less for water stored underground. Further, the risk of
contamination of the stored water from the surface is reduced because as
parasites cannot breed in underground water, The problem of submergence of
land which is normally associated with surface dams is not present with Sub-
surface dams.

 A Sub-surface Dam: A sub-surface dam intercepts or obstructs the flow

of an aquifer and reduces the variation of the level of the groundwater
table upstream of the dam. It is built entirely under the ground.
 Sand Storage Dam: It is constructed above ground. Sand and soil
particles transported during periods of high flow are allowed to deposit
behind the
dam, and water is stored in these soil deposits. The sand storage dam is
constructed in layers to allow sand to be deposited and finer material is
washed downstream A groundwater dam can also be a combination of these two
types. When constructing a sub-surface dam in a river bed, one can increase
the storage volume by letting the wall of the Dam rise over the surface, thus
causing additional accumulation of sediments, Similarly, when a sand-
storage dam is constructed, it is necessary to excavate a trench in the sand
bed in order to reach bedrock, which can be used to create a sub-surface dam
too.

Ferro cement Tanks:

Ferro cement tanks are containers which are much cheaper than masonry, RCC or
plastic tanks. Tanks of 1000-
2000-liter capacity can be
constructed with ease,
these are easy to repair,
and can be easily
transported because of
their sturdy nature. Such
containers have been used
on a wide scale since
about the past 25
countries. Ferro cement
containers with 21years in
Thailand, Malaysia
and some
African capacity as much as 5000 liters have been constructed in Thailand. The
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figure of a ferro cement tank is shown in figure 3.4.4. The process of building a Ferro
cement container is very simple which users can do themselves, with some
Fig 3.4.4 Ferro cement tank training. For a typical circular
pot-shaped container, the only materials required are hessian cloth, chaff (waste from
agricultural produce), GI wire mesh, MS bars, cement and sand.

3.6 TYPES OF RAINWATER HARVESTING IN INDIA

1. Water Butt:
One of the most basic types of rainwater harvesting systems; water Butt collects
rainwater in a container from natural rainfall and/or drain pipes. The collected water
is used mainly for watering the garden.

2. Direct-Pumped: Another very common and professional type of rainwater

harvesting,
 Submersible-Used particularly in domestic settings and is the casiest systems
to install. The pump is placed within the underground tank and the harvested
water is pumped directly to WCs or other appliances used daily for domestic
purposes.
 Suction-In this system, the pump is located within the control unit of the
house (e.g., utility room). This unit also deals with backup from the mains
water supply, hence there is no need to direct mains water down to the
underground tank.
Most rainwater harvesting systems need pumps to transfer the collected evn
from storage tanks to the point of use. Submersible pumps are generally more
than suction pumps and do not suffer from the same limitations.

3. Indirect Pumped:
This type of rainwater harvesting system doesn’t rely on gravity to supply water to
the outlets. Instead, it pumps the harvested water to a tank which can be at any level
in the building. Furthermore, a booster pump is used to provide a pressurized water
supply, One of the most significant benefits of this system is that it offers great
flexibility to tailor the booster pumps to adjust the flow and pressure requirements of
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a building.

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4. Indirect Gravity:
This system ensures water is supplied to the outlets by gravity alone. For this, the
harvested water is first pumped to the header tank, i.e., high-level tank and then
allowed to free-flow. In Indirect gravity systems, the pump works only to fill the
header tank.

5. Gravity Only:
In few conditions, a system which functions purely through gravity may be needed.
Such systems do not demand pumps hence involve no energy use. With such an
arrangement, water can be collected only when collection tanks are located below the
level of gutters, yet higher than the outlets which it will supply. Here the only power
of gravity is needed to feed collected and harvested water to various parts of the
household. Gravity only & one of the most energy-efficient rainwater harvesting
systems.

6. Retention Ponds:
Retention ponds are used to collect surface runoff water and improve the quality of
water by natural processes like sedimentation, decomposition, solar disinfection, and
soil filtration. This type of pond normally has a mud bottom, but in some cases, it
may be lined with concrete. The most common use of water collected and harvested
by pond harvesting is watering livestock, however, it can also be used for
groundwater recharge, irrigation or any other purpose other than potable uses.

7. In-Ground Storage:
Underground storage tanks are very popular in areas where the majority of rainfall
occurs in one single season. These underground tanks are insulated and have a very
low rate of evaporation. In addition, the water stored in these doesn’t freeze if it is
buried below the frost line, this is a huge advantage that surface storage tanks do not
offer. Underground tanks need to be connected to an electric pump to ensure supply
of the stored water to the outlets.

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3.7 RAINWATER HARVESTING BY FRESHWATER
Rainwater harvesting is possible by growing freshwater-flooded forests without
losing the income from the used, submerged land. The main purpose of the rainwater
harvesting is to use the locally available rainwater to meet water requirements
throughout the year without the need of huge capital expenditure, This would
facilitate the availability of uncontaminated water for domestic. industrial, and
irrigation needs.

3.8 RAIN WATER HARVESTING BY SOLAR POWER PANALS

Good quality water resource, closer to populated areas, is becoming scarce and costly
for the consumers. In addition to solar and wind energy, rainwater is major
renewable resource of any land. The vast area is being covered by solar PV panels
every year in all parts of the world, Solar panels can also be used for harvesting most
of the rainwater falling on them and drinking quality water, free from bacteria and
suspended matter can be generated by simple filtration and disinfection processes as
rainwater is very low in salinity. Exploitation of rainwater for value-added products
like bottled drinking water makes solar PV power plants profitable even in high
rainfall/cloudy areas by the augmented income from value-added drinking water
generation.

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DESIGN OF RECHARGE PIT
The design of the recharge pit is as shown in the Figure [4] below. From the bottom,
start filling the pit with different materials as shown. Connect the overflow outlet of
the rainwater harvesting tank with the inlet to the recharge pit. One can also direct
the slope of the floor to allow the rain water to collect in the recharge pit.

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[Fig.4]

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 CONCLUSION
The growing population and the rising demand for water have put a great deal of
pressure on the natural resources, Underground water is depleting at a very fast rate
and soon there will be shortage and scarcity of water all over the globe. If artificial
methods are adopted then this problem can be solved, Rainwater harvesting will not
only ensure flood control but it has other benefits like ensuring a continues supply of
water, pollution control ete, As per the discharge calculations for various intensities
of floods we can conclude that rainwater in itself is not capable of augmenting the
groundwater water table. So, we need to employ rainwater harvesting structures. The
effectiveness of rainwater harvesting system lies in its ability to meet the site
requirements and end use preferences. Though simple, these systems are site specific
and need to be detailed out before implementation. With decrease in availability of
water, rainwater harvesting presents the best option for times to come. Recently, the
interest in RWH systems as an alternative water source has increased, due to their
economic and environmental advantages. Indeed, these systems can provide a
supplementary water supply in urban areas when integrated with an existing
conventional water supply system, or the main water supply in rural areas affected by
water scarcity. In the context of climate change, the installation of RWH tanks could
represent a valuable adaptation measure against the reduction of water availability.

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 BIBLIOGRAPHY

[1] ANIL AGARWAL (2013): Manual on Rainwater Harvesting “Catch water

Where it Falls’’
[2] KIRAN. A, NIKHIL. T, R HARISH, J KULKARNI (2012): Harvested Rainwater
for Drinking- Research paper.
[3] ARIYABANDU R.D.S (2003). Very-Low-Cost Domestic Roof Water
Harvesting in the Hu-mid Tropics: Its Role in Water Policy. Sri Lanka Domestic
Roof Water Harvesting Research pro-gramme.
[4] SIVARAMAN, K.R & THILLAIGOVINDARAJAN S. (2003), Manual on
Rainwater Harvesting. Chennai, Akash Ganga.
[5] RAINWATER HARVESTING- austinenergy.com

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