Rain is Nature's boon to the entire humanity.
Every drop of rain water that falls on the
ground is like a pearl. It brings relief to the
dry land and replenishes the ground water. In a
developing country like India where people are
suffering from water scarcity, rain water can be
used to solve this problem through rain water
harvesting.
Harvesting of rain water is the collection of
rainwater into any natural resource like lake,
pond, etc. or any man-made resources for its
future usage for crop harvesting, toilet,
gardening, etc. It is also used for replenishing
the underground water. The easiest and the most
common rain water harvesting method is the
rooftop harvesting. With the help of this
technique one can collect huge volumes of clean
rain water during the rainy season and use it
for different household purposes like livestock,
gardening and irrigation.
Components required
Rainwater collection systems are available in
different shapes and sizes. It ranges from
simple catchment system under a downspout to
large underground and/or above cisterns with
complex filtration systems that can store huge
volumes of water. Most rainwater collection
systems comprise the following basic components:
Catchment surface: This is a rooftop or
other raised solid surface. The good quality
catchment systems have smooth, hard surfaces
such as metal concrete or roofs areas. Besides
the quantity of rainfall, the amount of water
harvested greatly depends on the size of the
surface and the incline of the catchment area.
Gutters and downspouts: They are also
referred to as distribution systems. They
channel water from the catchment area to a
holding container such as a cistern, barrel or
planted area.
Roof washers: These are devices that
divert the "first flush" of rain before it
enters the storage tank. It is always
recommended that the "first flush" of water is
diverted to an outside area of the storage
system as debris, bird droppings and other toxic
waste may accumulate at the catchment surface.
Leaf screens: These are screens that
catch or remove debris.
Storage tank: This is the most expensive
part of a rainwater harvesting system. Storage
tank can be underground or aboveground and is
available in numerous styles and types. It
should be made opaque to thwart the growth of
algae. The tank should be positioned on an
elevated area to harness the advantage of
gravity flow. It should be placed close to the
supply line and area of use to minimise the
distance over which the water is to be
delivered.
Purification/treatment system: This is
required for potable systems to make the water
safe for consumption.
Delivery systems: These are generally
pumped or gravity-fed to the landscape or other
end-use areas.
Need for rain water harvesting
This technique will help in preserving more
water by preventing the surface water runoff
during the monsoon. Harvesting of rain water
helps in improving the water quality in aquifers
and reducing the soil erosion. Recharge of
rainwater to the ground helps in diluting
nitrates, fluorides and salinity content of the
groundwater. In coastal areas recharge of
rainwater avoids sea-water immersion into the
fresh water bodies. Harvesting of rain water
helps in curtailing the water supply bills and
in minimizing the insecurity of the water
requirement of the households in the rural
areas. It also helps in controlling urban
flooding. It reduces people's demand for water
from the municipality. This in turn reduces the
energy consumption in distributing water supply
throughout the city.
Implementation of rainwater collection
systems
Rain water harvesting plays an important role in
improving the ground water table in both
indirect and direct manner for at least four to
six months. This technique is very effective in
the desert regions and hilly regions which
always regularly face water scarcity. It is for
this reason the government of our country has
given prime importance to this form of water
harvesting system. Several awareness programmes
have been launched at the village level to
educate the people about the benefit of
rainwater collection technique. Tamil Nadu is
the first Indian state where harvesting of
rainwater has been made mandatory by the state
government. On 30th of May 2014, Tamil Nadu
state government has declared to set up
approximately 50,000 rainwater collecting
systems at numerous places in Chennai. Till
date, about 4,000 temples in Tamil Nadu have
rain water tanks that are setup to cater to
various rituals in the temples.
Even though rain water harvesting is quite
expensive during the initial stages its benefits
are manifold. It is one of the clean and
non-polluting ways to preserve the natural rain
water for our use in the future.