Water & Wastewater Asia March/April 2021

VIEWPOINT WATER & WASTEWATER ASIA | MARCH/APRIL 2021
WELL WATER
mysteries unravelled
By Orest and Janina Protch
is of interest to water well users no
matter the size of the well. Not only
can well water bring up beneficial
chemical elements, it can also
bring up toxic chemicals and even
flammable gas.
The ground below is not a solid
Evapotranspiration
Condensation
Figure 1: The
hydrologic cycle is in
a constant state of
flux and so the water
chemistry is always
changing in a well
water system
barrier like a steel wall. It can be
made of soil, gravel, clay or solid
rock that has cracks running through
it. And all these allow water to move
relatively freely through it. And move
it does.
Precipitation
Areas like South Asia now account for
approximately 50% of groundwater
usage worldwide. With an estimated
20 million wells in the area, from small
wells supplying a small family farm to
those that supply the requirements of
large industries or towns and cities,
water use is increasing yearly.
Users of well water systems can get
complacent with them. Just because
they are out of sight does not mean
that they should be out of mind.
They need to be regularly serviced,
disinfected and the water chemistry
checked throughout the seasons,
preferably at the minimum, monthly.
WELL
WATER
QUALITY
Infiltration
We see rivers and lakes replenishing
continuously but the water in
underground water tables are
constantly replenishing too. If this
was not the case then our well water
systems would run dry.
No two well waters systems will give
the same waters in terms of chemistry
even if they are close to each other.
Underground water will dissolve
minerals, chemicals and nutrients. Well
water is affected by the hydrologic
cycle shown in Figure 1.
Runoff
It is what happens when water gets
below the surface of the ground that
Figure 2 (below):
Cones of depletion
form around the
wells being pumped.
Two wells at different
levels may have
cones that interfere
with each other.
Another nearby well
may be in the path of
toxic chemicals and
the others may be
uncontaminated.
A well draws water from the
surrounding three dimensional area.
The water moves sideways and
down-wards in through the ground
layers by hydraulic pressure and
gravity into the well zone. Think of
a cone forming around each pump
intake. If we pump water out faster
than can naturally flow into the well
then our pumps will cavitate. Wells in
close proximity can create cones that
overlap when pumping. And a formed
cone from one nearby well can be
in a water table zone that has water
being contaminated from industrial
chemical dumps or municipal dumps
as the chemicals percolate down
through the water table carried by
rain water (Figure 2).
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