Below-normal rainfall is likely until February next year, Rand Water said on Friday.
Rand Water, which uses 1% of the Vaal Dam’s water every two weeks, said the dam is 37% full.
”Once the level goes below 20%, we will start drawing in mud from the bottom into the intake tower, thus affecting our purification system,” said Rand Water’s head of catchment, Francois van Wyk.
”We cannot use the water at all if the level is below 11% — due to the mud content.”
Van Wyk said under normal conditions, a 37% water level would not be a problem at this time of year as the rainy season approaches.
The South African Weather Service, however, has warned that rainfall will be below average over the next four months.
”If we do not get rains … we might have serious trouble,” warned Van Wyk, who urged the public to use water sparingly.
If the Vaal Dam’s level drops too low, Rand Water has two options. It can either increase the flow from the Katse Dam to the Vaal Dam, ”but this is limited due to the capacity of the pipelines”.
Van Wyk said: ”The other, more likely, option is to release water from the Sterkfontein Dam, which is kept full for the specific purpose of augmenting the Vaal Dam in case of drought, and the dam has almost the same capacity as the Vaal Dam, so there is enough to see us through the next year.” — Sapa