This is the opinion of professor Yongxin Xu of the department of earth sciences at the University of the Western Cape (UWC).
Xu is a professor in hydrology and is involved in several projects related to sustainable water use in the Western and Eastern Cape.
He said on Monday that the Cape Flats' aquifer - a source of water found in underground rock - is an enormous undeveloped water source.
The Cape's water sources are surface dams, but many cities in Africa, such as Nairobi and Lusaka, are totally dependent on subterranean water because they have no other sources, Xu said.
These cities' aquifers are often severely polluted, but they are all the cities have. The water under the Cape Flats is not as badly polluted, he said.
Xu said more money should be allocated to research the subterranean water of the Cape Flats so that development, for example, is planned in such a manner as not to pollute this water source.
"We have to re-evaluate the Cape Flats. It is very important."
'Enough technical expertise'
Public opinion must be changed so that people start seeing the Cape Flats as a water source, he believes.
His department has already drilled five boreholes at the UWC and this source is so strong that the water table does not drop. However, there is no money for further research.
Xu said there was enough technical expertise to develop the subterranean water resource.
Conservative estimates state that 20 million m³ of water per year is available under the Flats. The Cape has a water shortage of about 4 million m³.
Water restrictions were introduced to save water, but he said the question should be raised whether all other options were considered.
The Cape's other big aquifer is in the Table Mountain complex area. This aquifer is very rocky, but, if utilised with the Cape Flats aquifer, there should be no water problems in the area, Xu explained.
The Table Mountain aquifer stretches from the Western Cape to the Eastern Cape.
Xu is part of a United Nations' environmental programme (Unep) team that is involved in studying underground water in many African cities.