The City is planning to abstract 80million cubic metres of ground water from the Cape Flats aquifer, 30million cubic metres from the Atlantis aquifer and 40million cubic metres from the Table Mountain Group aquifer. There are also 22000 registered boreholes in Cape Town.
According to World Wildlife Fund (WWF) senior manager for fresh water, Christine Colvin, if we take out more water than is going in, we will run out eventually. “Our current groundwater store has been built up over decades by rainfall. Because groundwater is a large store of water, it takes longer than rivers and dams to feel the effects of drought. But to ensure that there is a fair share of this hidden resource for everyone, we need to measure how much we use, monitor the water levels and be sparing.
“If a lot of groundwater is abstracted close to the coast there is a danger of seawater intruding into the aquifer: salt water fills the aquifer and this water can't be used by homeowners or farmers unless it is desalinated back to freshwater. As a coastal city, Cape Town has to monitor and manage this risk if boreholes are drilled below sea level.”
Colvin explained that when we pump groundwater, the water table dropped and boreholes pumping close to each other could interfere with each other and bring down the water table even more.