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Water Conservation Practices
Presentation · April 2019
DOI: 10.13140/RG.2.2.13771.03365
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Water Conservation Practices
by
Prof. A. Balasubramanian
Dept. of Studies in Earth Science
University of Mysore
Mysore, India
1
Introduction:
Water is a very important resource in our life. Water is becoming scarce due to increase in
Population, industries and agricultural activities and due to poor rainfall.A report of 2009 suggested
that by 2030, in some developing regions of the world, water demand will exceed supply by 50%.
Water plays an important role in the world economy, as it functions as a solvent for a wide variety of
chemical substances and facilitates industrial cooling and transportation.
Goals of Water Conservation
1) Sustainability: To ensure availability for future generations, the withdrawal of fresh water from
an ecosystem should not exceed its natural replacement rate.
2) Energy conservation: Water pumping, delivery, and wastewater treatment facilities consume a
significant amount of energy. In some regions of the world over 15% of total electricity consumption
is devoted to water management.
3) Habitat conservation: Minimizing human water use helps to preserve fresh water habitats for
local wildlife and migrating water flow, as well as reducing the need to build new dams and other
water diversion infrastructure.
Water harvesting and conservation
Water conservation refers to reducing the usage of water and recycling of waste water for different
purposes like domestic usage, industries, agriculture etc.
Methods of Water Conservation:
1. Protection of Water from Pollution;
2. Redistribution of Water
3. Rational Use of Groundwater
4. Renovation of Traditional Water Sources
5. Use of Modern Irrigation Methods
6. Increasing Forest Cover
7. Change in Crop Pattern
8. Flood Management
9. Conserving Water in Industries
10. Conservation of water by Municipal authorities
11. Use rainwater effectively
12. Make effective use of soil water reserves
13. Take measures to avoid run off
14. Avoid wasting water through evaporation
15. Reduce water losses through drainage
16. Plan your irrigation
17. Contour Farming& Contour Ploughing
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Contour Furrows
Bench Terraces
Grass Strips
3
Stone Lines
Retention Ditches
Planting Pits
4
Earth Basins
Semi-Circular Bunds
Cover Crops/Green Manures
5
Mulching
Drip Irrigation
Conservation Tillage
6
Water Harvesting from External Catchment
Roof Top Harvesting
Rainwater Harvesting
Rainwater Harvesting is an effective method and a simple method of collecting water for future usage.
Rainwater harvesting is the process of collecting, filtering, storing and using rainwater for irrigation
and for various other purposes.
Rainwater is collected when it falls on the earth, stored and utilized for various purposes. It can be
purified to make it into a drinking water facility in some islands and dry land regions.
Rainwater harvesting (RWH) is a simple method by which rainfall is collected for future usage. The
collected rainwater may be stored, utilised in different ways or directly used for recharge purposes.
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Benefits of Rainwater Harvesting
Rainwater harvesting has many benefits. The major benefit is that it is a sustainable water
management practice. It can be implemented by every citizen at various levels. It is a socially
acceptable practice and promotes environmentally responsible future.
The rainwater that falls on any roof and property is essentially free. All it needs is to adopt a method
to harvest it and store it in a tank or cistern for future use.
Rainwater harvesting helps to reduce the peak demand of water expected during summer period, by
saving treated water for more important water uses.
While rainwater can be a perfect primary water source for many uses and situations, it is would be a
good backup water supply for emergency situations.
The Environmental Benefits
Rainwater harvesting can reduce storm-water runoff and wastage from any land. The reduction in
runoff volume can reduce the level of contamination of surface water resources with pesticides, solid
wastes, municipal effluents, sediments, metals, and fertilizers.
By reducing the storm-water runoff, rainwater harvesting can reduce the flow volume and velocity in
local streams, and rivers. This also help to avoid the potential for erosion along river beds.
Rainwater harvesting systems can be an excellent source of water for growing plants and carry out
landscape irrigation.
The Economic Benefits
Collecting and using rainwater, in place of municipal water supply, reduces the water bill to some
extent. This also reduces the water service cost to a municipality, for their people.
Rainwater harvesting can reduce water demand from municipalities. It helps to provide potable
water at a lower cost. Designing and installing rainwater collection systems can provide sustainable
jobs for people and help to earn more.
The rainwater harvesting industry can become a leading employer in the green infrastructure
movement. Rainwater stored onsite in a rainwater harvesting system can avoid increasing forest fires.
Insurance companies can offer better discounts for those who implement better water management
practices.
Miscellaneous Benefits
Rainwater doesn’t have the any chemicals in it. Rainwater can be used for irrigation. It is a suitable
potable water source. Rainwater harvesting can provide an independent water source in areas where
other water sources are not available.
In some places where the water quality is poor, we may use rainwater, safely.
Good rainwater provides many advantages.
Rainwater harvesting is the key to the future water conservation gains.
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Rainwater harvesting is a vital resource for the future of sustainable water resources. Reduce demand
on Ground Water.
Rainwater harvesting is part of a sustainable water supply strategy for local communities.
Rainwater for Non-drinking Purposes:
Rainwater can be used for several non-drinking purposes like flushing toilets, washing clothes,
watering the garden, washing cars etc. It is a unhealthy practice to use pure drinking water some other
purposes other than drinking.
Disadvantages of Rainwater Harvesting
Rainfall is unpredictable. There is an Initial Cost for establishment.
Rainwater harvesting systems require regular maintenance.
There are limitations in storage tank capacities.
Techniques of Rainwater Harvesting
Rooftop rainwater harvesting (RTRWH) is the most common technique of rainwater harvesting
(RWH) for domestic consumption. In urban and rural areas, this is most often practiced method at a
small-scale. It is a simple, low-cost technique that requires minimum specific expertise or knowledge.
Rainwater is collected from the roof top and transported with gutters in to a storage reservoir, where it
provides water at the point of consumption or can be used for recharging a well or the aquifer.
Collected rainwater can be the best supplement to other water sources when they become scarce or are
of low quality like brackish water, saline groundwater or polluted surface water, in the rainy season.
The technology is flexible and adaptable to a very wide variety of geographic and geomorphic
conditions. It is used in the developed and the developing societies.
Roof Top Rain Water Harvesting
Basic design principles
Each rainwater harvesting system consists of at least the following components:
A catchment area in the roof surface to collect rainwater.
A delivery channel (gutters) to transport the water from the roof or collection surface to the storage
reservoir.
Storage tanks or reservoirs to store the water until it is used.
An extraction device (depending on the location of the tank).
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(Three basic components of a rainwater harvesting system. Source: HATUM WORM (200 6)).
&
(Surfac e tank made out of ferro-cement for the storage collected inwater. Source: DOL AN &
LUND Qo UIST (2008)) r a M
Factors to be considered
Type and size of catchment area
Local rainfall data and weather patterns
Length of the drought period
Alternative water sources
Cost of the rainwater harvesting system.
When rainwater harvesting is mainly considered for irrigation, several factors should be
taken into consideration. These include: Rainfall amounts, intensities, and evapo-
transpiration rates. Soil infiltration rate, water holding capacity, fertility and depth of soil .
Crop characteristics such as water requirement and length of growing period .
Hydrogeology of the site .
The Basic Calculation
Roof top flat area:
4m by 5m = 20 Sq. m
total annual total annual rainfall in mm = 500 mm
efficiency factor / runoff coefficient = 0.9
Annual water suppl
y in liters = 20 x 500 x 0.9 = 9000 liters
Rainwater Collection -Calculation Formulas and Equations
Roof Area (ft2) X Precipitation Amount (in) X 0.623 = Amount Collected (gallons)
How to choose the size of the storage tank:
A house with a roof area of 9.00 x 6.50 m is to be furnished with catchment and storage facilities. The
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mean annual rainfall is 450 mm.
11
Calculation of rainwater:
9.00 x 6.50 x 450 x 0.9 = 23895 litres
Tamil Nadu:
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.
Karnataka -World’s largest rainwater harvesting project:
The World’s largest rainwater harvesting project was carried out in Karnataka.
Rainwater harvesting in rural Karnataka’ funded by Rural Development and Panchayat Raj
Department (RDPR), Government of Karnataka is probably the largest rainwater harvesting project in
the world. All the schools of Karnataka were carefully studied for the water availability, quality
(fluoride contamination) and proximity to the secondary water source.
Almost 23,683 schools were identified in the first phase to provide drinking water through rooftop
rainwater harvesting systems.
Steps taken by the Central Government to promote rain water harvesting in the country are as
follows:
1. Central Ground Water Board (CGWB). Govt of India, has prepared a conceptual document titled
“Master Plan for Artificial Recharge to Ground Water – 2013.
2. The National Water Policy (2012) formulated by Ministry of Water Resources, RD & GR, inter-
alia, advocates conservation, promotion and protection of water and highlights the need for
augmenting the availability of water through rain water harvesting, direct use of rainfall and other
management measures.
3. CGWA( Water Authority) has issued advisories to States and UTs to take measures to
promote/adopt artificial recharge to ground water/rainwater harvesting. 30 States/UTs have
made rainwater harvesting mandatory by enacting laws or by formulating rules & regulations or
by including provisions in building bye-laws or through suitable Government Orders.
4. CGWB has taken up Aquifer Mapping and Management programme (NAQUIM) during XII Plan,
under the scheme of Ground Water Management and Regulation.
5. Model Building Bye Laws, 2016 circulated by Ministry of Urban Development include the
provision of Rainwater Harvesting. As per Model Building Bye Laws, water harvesting through
storing of water runoff including rainwater in all new buildings on plots of 100 sq.m and above will
be mandatory.
6. The Ministry of Rural Development in consultation and agreement with the Ministry of Water
Resources, RD & GR and the Ministry of Agriculture & Farmers’ Welfare has developed an
actionable framework for Natural Resources Management (NRM), titled “Mission Water
Conservation” to ensure gainful utilization of funds.
Types of common works undertaken under these programmes/schemes are water conservation and
management, water harvesting, soil and moisture conservation, groundwater recharge, flood
protection, land development, Command Area Development & Watershed Management.
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The government of India is working on a master plan envisaging construction of about 23 lakh
artificial recharge and rainwater harvesting structure in rural areas and 88 lakh in urban areas, as
informed in the Lok Sabha, already.
Conclusion:
In many cases, groundwater or surface water may be unavailable for drinking water. The
groundwater level may be too deep, groundwater may be contaminated with minerals and chemicals
such as arsenic or salt, surface water may be contaminated with faeces or chemicals. In these cases,
rainwater harvesting can be an effective and low-cost solution.
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