Advantages of rainwater harvesting

ADVANTAGES OF
RAINWATER HARVESTING
BY
ANAND NARAYANAN D

INTRODUCTION
 Rain water harvesting is the
accumulation/deposition of rainwater
for reuse before it reaches the aquifer.
 Rain water harvesting means collecting
rain water from the top of roof or
building, open spaces surrounding the
buildings, farm-areas , etc. And then
storing it for a later use or diverting it to
an existing well for recharging.

 Rainwater harvesting is an environmentally sound solution to
address issues brought forth by large projects utilizing centralized
water management approaches.
 Population growth all over the world is causing similar problems and
concerns of how to supply quality water to all.
 There is now increasing interest in the low cost alternative generally
referred to as 'Rain Water Harvesting' (RWH).
 Rainwater harvesting may be one of the best methods available to
recovering the natural hydrologic cycle and enabling urban
development to become sustainable.
 Rainwater collection has the potential to impact many people in the
world.

Need of Rainwater Harvesting:-
 As water is becoming scarce, it is the need of the day to attain self-
sufficiency to fulfill the water needs.
 As urban water supply system is under tremendous pressure for
supplying water to ever increasing population.
 Groundwater is getting depleted and polluted.
 Soil erosion resulting from the unchecked runoff.
 Health hazards due to consumption of polluted water.

BENEFITS & ADVANTAGES OF
RAINWATER HARVESTING
 Rainwater harvesting has many benefits but the main one is that it
is a sustainable water management practice that can be
implemented by anyone on many different levels, from a simple rain
barrel to a comprehensive rainwater harvesting system that
integrates with an irrigation system or household plumbing.
 Harvested rainwater is the perfect candidate for irrigation use in
addition to so many other water uses.
 By using rainwater harvesting systems to supply water for some, or
all of our water needs, you can reduce our dependence on
municipally treated water.

1. THE WATER CONSERVATION BENEFITS OF RAINWATER
HARVESTING
 The rainwater that falls on your roof and property is essentially free. All
it takes is a method to harvest it into a tank or cistern for later use.
 For communities that rely on imported water to supply their needs,
collecting rainwater that falls naturally in the community can reduce the
need for imported water.
 Rainwater harvesting helps utilities reduce peak demands during summer
months, saving treated water for more important and appropriate water
uses.
 While rainwater can be a perfect primary water source for many uses and
situations, it is also a great backup water supply for emergency
situations.

2 . THE ENVIRONMENTAL BENEFITS OF RAINWATER
HARVESTING
 Rainwater harvesting can reduce stormwater runoff from a property. The
elimination of runoff can reduce contamination of surface water with
pesticides, sediment, metals, and fertilizers.
 By reducing stormwater runoff, rainwater harvesting can reduce a storm’s
peak flow volume and velocity in local creeks, streams, and rivers, thereby
reducing the potential for streambank erosion.
 Rainwater harvesting systems can be employed as simple and effective
methods to meet a municipality’s stormwater management program
requirements of individual properties.
 It is an excellent source of water for plants and landscape irrigation since
it has no chemicals such as fluoride and chloramines (chlorine).

3. THE WATER-ENERGY NEXUS BENEFITS OF RAINWATER
HARVESTING
While the logical use of rainwater harvesting is for water conservation
purposes, it also reduces energy use within a community.
 Replacing municipal water use at a home and property with
rainwater reduces the amount of water that a municipality has to
treat and then pump to your house. The treatment and pumping
of municipally provided water require a lot of energy.
 The implementation of rainwater harvesting can help meet new
standards of energy and water efficiency ratings and codes that are
being developed in communities.

The traditional path of rainwater through our local water
ecosystem and how it gets to our homes:

The simplified path available through the implementation of
rainwater harvesting:

4. THE ECONOMIC BENEFITS OF RAINWATER HARVESTING
 Collecting and using rainwater to replace municipal water use reduces your
water bill.
 Reducing municipal water use for areas such as irrigation reduces the
amount of water that a municipality has to treat and pump. This, in turn,
reduces water service cost to a municipality.
 The cost to the community to supply treated water is becoming more
expensive every year. The cost to construct dams, pipes, and treatment
plants, not to mention the cost of maintenance and infrastructure
replacement is huge.
 Therefore, the practice of rainwater harvesting can reduce water demand
and thus allow municipalities to provide potable water service at a lower
cost.

5. THE ANCILLARY BENEFITS OF RAINWATER HARVESTING
 Rainwater can be used for irrigation use, indoor non-potable water use,
and/or potable water supply.
 Rainwater harvesting can provide an independent water source in areas
where other water sources are unavailable, or the water quality is
unacceptable, or they are too expensive to develop, or they are too
difficult to obtain.
 If used as a potable water source, the zero hardness of rainwater provides
many advantages. It eliminates the scale build-up in household
appliances that could occur with the use of other water sources. This will
extend the life of the appliances. In addition, it reduces the amount of
detergent or soaps needed in laundry and dishwashing appliances,
reducing money spent on these detergents and soaps.
 Rainwater from a potable rainwater harvesting system that has been
properly filtered and disinfected is some of the best tasting water
available. It doesn’t have the many chemicals that municipally treated
water has such as fluoride or chloramines (chlorine).

Disadvantages of Rain Water Harvesting
 Unpredictable rainfall-Rainfall is hard to predict and sometimes little
or no rainfall can limit the supply of rainwater
 Initial cost of rainwater harvesting system is too much high.
 Regular Maintenance- Rainwater harvesting systems require regular
maintenance as they may get prone to rodents, mosquitoes, algae
growth, insects and lizards.
 Certain types of roofs may seep chemicals, insects, dirt or animals
droppings that can harm plants if it is used for watering the plants.
 Storage limits- During the heavy downpour, the collection systems
may not be able to hold all rainwater which ends in going to drains
and rive

Methods of harvesting water:
• Tanks and reservoirs are used to store the water.
• By building pits, dug wells and by recharging ground water.
Rainwater can be harvested from the following surfaces:
• Surface runoff Harvesting: In towns and cities, rainwater flows as
surface runoff and this could be stored for the future use by
implementing correct methods.
• Rooftop Rainwater Harvesting: In this method, the rainwater is
directly stored, at where it falls. The components needed in this
type of harvesting are:
i. Catchment
ii. Transportation
iii. First flush
iv. Filter

i. Catchment: The surface which takes the rainwater is called
catchment and the catchment may be a terrace, open ground area
etc.
ii. Transportation: The water from the catchment is taken down
through the pipes to the harvesting place.
iii. First flush: the First flush is a machine provided at the outlet of
transportation pipes and used to flush the water to avoid any
contamination.
iv. Filter: At the peak points of the storage tanks filters are present
which aids in removing all the dust particles present in water
before storing it in the reservoir or tank.
Rooftop harvested rainwater can be used in different methods and
some of them are as follows:
• The storage can be used directly.
• The stored water can be used to recharge the ground water.

RAINWATER HARVESTING IN INDIA
 Tamil Nadu was the first state to
make rainwater harvesting
compulsory for every building to
avoid groundwater depletion.
 The scheme was launched in 2001
and has been implemented in all rural
areas of Tamil Nadu. Posters all over
Tamil Nadu including rural areas
create awareness about harvesting
rainwater.
 It gave excellent results within five
years, and slowly every state took it
as a role model.
 Since its implementation, Chennai
had a 50% rise in water level in five
years and the water quality
significantly improved

Marakkanam Town Panchayat
(Villupuram District)
Kalavai Town Panchayat (Vellore District)
Thirupuvanam (Thanjavur District) Thazhkudi (Kanniykumari District)

 Karnataka: In Bangalore, adoption of rainwater harvesting is
mandatory for every owner or the occupier of a building having the
site area measuring 60 ft m × 40 ft and above and for newly
constructed building measuring 30 ft × 40 ft and above dimensions.
 In this regard, Bangalore Water Supply and Sewerage Board has
initiated and constructed “Rain Water Harvesting Theme Park” in
the name of Sir M. Visvesvaraya in 1.2 acres (4,900 m2) of land
situated at Jayanagar, Bangalore.
 In this park, 26 different type of rainwater harvesting models are
demonstrated along with the water conservation tips. The
auditorium on the first floor is set up with a "green" air
conditioning system and will be used to arrange the meeting and
showing of a video clip about the rainwater harvesting to students
and general public.

 In Rajasthan, rainwater harvesting has traditionally been
practiced by the people of the Thar Desert. Many ancient water
harvesting systems in Rajasthan have now been revived. Water
harvesting systems are widely used in other areas of Rajasthan, as
well, for example the chauka system from the Jaipur district.
 Maharashtra: At present, in Pune, rainwater harvesting is
compulsory for any new housing society to be registered.
 In Mumbai, Maharashtra, rainwater harvesting is not mandatory.
The Mumbai City council is planning to make rainwater harvesting
mandatory for large societies

CASE STUDIES ON RAINWATER HARVESTING
1. Rainwater Harvesting- A Case Study of Amba Township,
Gandhinagar(2015)
• Amba Township is located at distance of 10kms from
Gandhinagar, state-Gujarat (India).It lies between latitude
23°11’17” N and longitude 72° 34’32” E. Amba Township is just on
the outskirts of Gandhinagar. The population of township is around
1000.
• The total area of roof top of all buildings in Amba Township is
22011 Sq.m and average annual rainfall in Gandhinagar is
740.3mm.

• Amba Township is 10kms away from the Gandhinagar, so there is no
any water supply from Municipal of Gandhinagar. There is no any
reliable source of water in Amba Township.
• So there is need to dug a private bore wells in Amba Township. But
day by day buildings are constructed and population of city are
increasing as faster way. Due to this, water demand is also increasing.

• Population:- So, in last 5 year the population of AmbaTownship
is increase in this manner:-
• So, in future the city will facing a various water problems.
Because ground water is depleted too much due to increase in
water demand. So, to solve this problem Rain Water Harvesting is
an only low cost harvesting technique to solve this problem.

Rainfall and Climate:-
• Gandhinagar has a tropical wet and dry climate with three main
season: summer, monsoon, winter. The climate is generally dry and
hot outside of the monsoon season. The weather is hot to severely
hot from March to June when maximum temperature is 45°c and
minimum temperature is 10°c.
• The rain fall data of last 5 years is:-

Total average annual rainfall of Gandhinagar = 740.3mm
Water Demand:-
• As per IS Specification (IS 1172: 1993), Total water demand for
one person = 135 lit/day
• Total water demand = 135*1000
• Annually total water demand = 365*135*1000
• Annually total water demand = 4, 92, 75, 000 lit

• In Amba Township in sector-3 (A, B) there are presently 4
Percolation well. Which collect all surface water and store it into
ground water. There are total 5 sector in Amba Township which also
collect rain water through road network so all the water are flow
into direction towards main percolation well. So that’s way
ultimately main percolation well should be recharge.

Result & Analysis
• Here we study only for sector-3 (A, B). Which collect annually 1,
46, 27, 284 lit water and this much amount of water can be
absorbed by 4 percolation well and if there is high intensity of
rainfall then excess amount of runoff can be flown towards the
main percolation well through the road network as shown in
previous figure.
• So this way we can harvest the rain water and increase the ground
water. We can harvest annually 1, 46, 27, 284 lit water which is
29.68% of total water demand.
• So by using Rain water harvesting methods we can harvest and
store the rain water into ground aquifer or into percolation well.

2 . Rainwater Harvesting for Sustainable Development : A
Case Study
 The present study emphasizes on the rainwater harvesting and
artificial recharge in IWMP-VI watershed Haryana.
 It also explains the various methods of rainwater harvesting and
artificial recharge to mitigate the problem of groundwater decline.
The study is based on the secondary data available from the report
and survey.
 Government of India focuses on groundwater recharge and water
harvesting under Pradhan Mantri Krishi Sinchai Yojana (PMKSY)
through Integrated Watershed Management Programme (IWMP).

Rainfall Pattern
 Although total rainfall seems to be insufficient for crops in the area
but the unreliable nature of rainfall leads to periodic drought and
soil erosion.
 60-70% of the annual rainfall occurs during summer monsoon
months (June-September).
 The rains are especially erratic in time and space. However, most of
the rainstorms received in monsoon season are of short duration
and high intensity, whereas those received in winter season are of
low intensity and erratic in distribution in the area.

Water Scarcity–A Problem
 Water is available in limited amount and utilization of water with high
rate. The difference between demand and supply creates unbalance in
water supply.
 Groundwater and canal water are main sources of water resource in
Hisar area.
 All canals in Hisar region are the branches of Western Yamuna Canal. So,
discharge in Yamuna also affects the availability of water in these canals.
 So, farmers go for second option, groundwater. But groundwater is not of
good quality and lower in soil profile.
 But farmers and people in village use groundwater for irrigation and
domestic purposes by installing submersible and hand pumps. This is
going on for a long time and hence, groundwater are depleting
continuously.

 Wells which were formed from 19th century are dried.
 Thousands of traditional water harvesting systems had declined
due to improper want of maintenance and use.
 There is a growing awareness regarding traditional water
harvesting systems that it is a better and cheaper alternative to big
or small dams.
 Groups of villages (in some rural areas) have revived small water
harvesting systems and are enjoying the benefit.

Rainwater Harvesting :-
 In Burak village of district Hisar, rooftop rainwater harvesting
system is installed. IWMP scheme funded all expenses.
 The capacity of this structure is 20,000 litre. In every season,
15000-18000 litre water is saved in this tank. This water is used for
domestic purposes.
 In Burak and Balsamand villages, IWMP scheme funded the
storage tanks. These storage tanks are built on panchayati land.
 Rainwater is harvested into these tanks. Such a huge amount of
water is saved in it. This water is further used for domestic and
irrigation purposes

 This effort of villagers with
IWMP agency brought a good
change in community.
 These villages have become
the example for other nearby
area.
 In Balsamand, rooftop
rainwater harvesting system
and storage tank have been
installed.

 From the survey of groundwater, it was observed that there was
groundwater of poor quality and deep. There was need of
enhancing the groundwater.
 Injection wells were installed by IWMP agency to recharge
groundwater. Rainwater percolates down and water table to be
replenished.
RESULTS :
 The rainwater harvesting during monsoon and its use for irrigation
during scarcity period was found to increase the crop yield by 10-
15% during crop season and additional water for population use by
55% in the area.

CONCLUSION
 As you can see from the benefits and advantages listed above, the
practice of rainwater harvesting is an important and vital part of
developing a sustainable water resource path for any community.
 From the two case studies we have gone through , we can conclude that
rainwater harvesting is very helpful technique to mitigate and face the
future water crisis.
 In the first case study in Amba township, we saw that 29.68% of total
water demand has been harvested from rainwater harvesting.
 So by using Rain water harvesting methods we can harvest and store
the rain water into ground aquifer or into percolation well

 From the 2nd case study on Hisar area, we saw that the rainwater
harvesting was found to increase the crop yield by 10-15% during crop
season and additional water for population use by 55% in the area.
 After installation of various harvesting structures, water quality improved
and water table rose in the region.
 It can be concluded from above findings that rainwater, if conserved and
utilized using the rainwater harvesting technology, can be an effective
tool of replenishing ground water resources.
 By mitigating and proper maintenance of rainwater harvesting system ,
we can reduce its negative impacts and use it to reduce water usage from
other resources and for groundwater recharging.
 Rainwater harvesting is vital for the future of sustainable water resources

REFERENCES
 Rainwater Harvesting- A Case Study of Amba Township, Gandhinagar,
Anant D. Patel , Asst. Prof. Pratima K. Shah, April 2015 ,
https://www.researchgate.net/publication/317379414
 Rainwater Harvesting for Sustainable Development : A Case Study
ARVIND, NARENDER KUMAR , HIMANSHU MISHRA, MANMOHAN SINGH
AND PANKAJ DAHIYA ,April 2019,
https://www.researchgate.net/publication/328576350
 Benefits and advantages of rainwater harvesting , Chris Maxwell-Gaines ,
https://www.watercache.com/faqs/rainwater-harvesting-benefits
 https://www.slideshare.net/gauravhtandon1/rainwater-harvesting-
46361326
 http://www.tn.gov.in/dtp/rainwater.htm

 http://www.tn.gov.in/dtp/rainwater.htm
 https://www.cseindia.org/urban-rainwater-harvesting-case-
studies-from-different-agro-climatic-regions-5408
 https://en.wikipedia.org/wiki/Rainwater_harvesting#Advantages
 https://www.conserve-energy-
future.com/advantages_disadvantages_rainwater_harvesting.php
 http://vikaspedia.in/energy/environment/rainwater-harvesting-
1/rainwater-harvesting#section-3

Advantages of rainwater harvesting

Advantages of rainwater harvesting

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