The letter “City steps up water testing in response to residents’ concerns” by executive mayor Patricia de Lille (Cape Times, November 22) once again warns Cape Town residents that the last 10% of the water in the larger reservoirs that supply the city is not usable.
This 10% amounts to 89.8 million cubic metres, or 89.8 billion litres, of water.
Put into perspective, this is equivalent to the total quantity of water stored in the Wemmershoek plus Steenbras Upper Dams when both are full.
This quantity of water is sufficient to supply the city for 180 days, if the water use is brought down to the target of 500 million litres a day.
Various reasons, such as the difficulty of purifying and/or abstracting the water, have been put forward in support of the statement that the last 10% is not usable.
This has been publicised in the press for about a year.
It appears as if the authorities prefer to ignore this source of water in favour of an emergency plan that includes the construction of desalination plants and other relatively small-scale projects.
These could be followed by draconian water rationing of 25 litres a person a day.
To make matters worse, this water will have to be collected at only some 200 watering points.
On average, each of these watering points will have to serve in excess of 10 000 people daily and dispense more than 250 000 litres of water a day.
While there is still some time available, the primary focus of the City of Cape Town should be to prepare to abstract and treat the 89.8 million cubic metres of water that it plans to ignore, and not punish the residents further for the poor decisions that the authorities have taken in the past.