Water, Sewage & Effluent March April 2019 | Page 28

Boreholes to tap local sources are limited and if too many boreholes are drilled and too
much water extracted, they will simply dry up.
emerging from Cape Town is about the
way groundwater can help to provide a
secure water supply. Groundwater runs
through many parts of the city’s new
water strategy, out for consultation last
month. But what is not clearly explained
is how it contributes to the city’s long-
term needs.
It is obviously a source of additional
water. Equally important, water can
be stored underground for when it is
needed — aquifers can be thought of
simply as underground dams. Finally,
as water flows underground, many of
the impurities that it brings from the
surface are filtered out, so putting
water underground can be a form of
treatment.
Given this magic combination of
supply, storage, and treatment, why
has it not been used more, before? The
answer is simple. As the City’s Plan
says, surface water is simply cheaper
than the other alternatives. But now
that there are no further sources of
surface water, new approaches are
needed, and because of the different
services that it offers, groundwater will
be increasingly important.
First, it will simply help to increase
supplies. During the crisis, many
businesses and households drilled
boreholes to tap local sources. But
that source is limited and if too many
boreholes are drilled and too much
water extracted, they will simply dry up.
The Table Mountain Group, a major
aquifer that runs from the West Coast
to Algoa Bay, is known to yield plentiful
water and is already being used in the
The City starts drilling operations for
groundwater from the Cape Flats aquifer
in Mitchells Plain, Cape Town.
As water flows underground,
many of the impurities that
it brings from the surface
are filtered out — so putting
water underground can be a
form of treatment.
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Water Sewage & Effluent March/April 2019
www.waterafrica.co.za