Water, Sewage & Effluent March April 2019 | Page 29

innovations
Southern Cape. Nearer to Cape Town, it hasn’t been
used before because it is deep and expensive to
connect to existing supply infrastructure. The City now
plans to tap it — although this has been the position
since at least 2007. The important contribution of
the Table Mountain aquifer is that it is very large —
effectively a large, permanent underground dam.
Most interesting is the Cape Flats aquifer, a shallow
source, closer to the city but, unfortunately, quite
polluted. It is also relatively small and easily depleted
but this may now be an advantage. Properly managed,
the aquifer can be used to help treat wastewater
that will be injected in through recharge wells and
then pumped out elsewhere — as is already done in
Windhoek, Namibia. In this way, the water balance
in the aquifer can be maintained and it can provide a
reliable stream of non-potable water for industry or,
with further treatment, used to increase the supply to
the city’s potable water treatment plants.
So, within a decade, groundwater will be storing,
supplying, and helping to treat and reuse the city’s
water. This will cost more than water from those big
surface water storage dams. But after the experience
of the past few years, Capetonians are surely willing to
pay the cost.
Meanwhile, back in Singapore, experts from PUB,
the local public utility water supply, shook their
heads sadly. “If only we had that kind of groundwater
resource, we could be self-sufficient,” they lamented.
The reason for their supply shortage was that they still
depend on a dam in neighbouring Malaysia; during the
drought there, levels fell below 20%.
So, it’s not just Table Mountain that distinguishes
Cape Town from Singapore. Capetonians can also give
thanks for those hidden resources right beneath their
feet. 
www.waterafrica.co.za
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