A 2 part poster to detail out borewells

1. HOW DO I DIG
A BOREWELL?*
1
A PVC or galvanised iron casing pipe
is used to prevent the borehole from collapsing.
Part of it would be visible above the ground. It is
installed till the depth at which hard rock layer
starts, and is usually 4, 6, 8, 12 or 24 inches in
diameter, half inch lesser than that of the borewell.
A “submersible pump”
of appropriate power rating is inserted into the
borehole, typically below the lowest crack from
which water has jutted out into the borehole. This
pump has a “delivery pipe” attached which comes
up all the way up to the surface. The pump delivers
the water from this pipe, which is collected by the
borewell users.
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2.
LOOK UP:
measuring
yield
A common way to describe the
yield of a new borewell is in
‘inches’ measured by the free,
unrestrained flow of water from
a borewell over a 90 degree ‘V’
notch. The basic principle is that
the discharge is directly related
to the height of
the water level
from the bottom
of the V notch.
Understanding
borewell
WATER qualityDeeper borewell water usually has less
microbial contamination than open well
water as its water has trickled down through
more rock layers. It is more susceptible to
geological contamination for the same
reason. Therefore these waters tend to be
high on TDS (total dissolved salts).
Water percolates down mainly during rain,
but also from other sources like lakes – a
process termed recharge. This is why
borewell water has to be tested regularly to
ensure that it is not contaminated.
In some areas, while trickling down, the
water comes in contact with
naturally-occurring salts like fluorides and
arsenic. India has many states which are
fluoride affected (e.g.: parts of Karnataka )
and many states that are affected by Arsenic
(e.g. parts of Bihar, West Bengal)
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3.
3
Borewell
metering and
maintenance
Meter your borewell and keep a log of how much water
you're pumping
Ensure regular camera Inspections
Recharge dry borewells and don’t rely only on borewell
water by diversifying your sources and incorporating
rainwater harvesting
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2.
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4
What do I do if my
borewell goes dry?
You could start with a camera inspection which will help you see
inside the borewell.
You could in the short term opt for hydrofracturing, a process
that involves injecting water under high pressure into a bedrock
formation via the well. This should clean and increase the size
and extent of existing fractures, and connect them with nearby
water bearing fractures. This is however not recommended as
it can affect neighbouring borewells.
However, in the longer term it’s advisable opting for
groundwater recharge solutions
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5
2
borewell
basics
pump motor
WEATHERED
ZONE
SOIL
casing
borehole
WEATHERED and
fractured ZONE
HARD ROCK
water level
pump
borewell rig
drilling the
borehole
Waterflow
end view
h
b
p
*Insist that your borewell digger
give you a borewell log.
V Notch
reading in
inches
Approx
discharge
rate
in lph class
1 597 low yield
2 3382 high yield
3 9329 very
high yield