File: A general view of rising water at the Vaal Dam on March 11, 2014 in Johannesburg.
JOHANNESBURG - Vaal Dam levels have slipped below 40%, despite the heavy rain in Gauteng.
According to Rand Water, dam levels stood at 39% on Monday whereas, during the same time last week, it was at 40.8% capacity.
The utility said there are a number of factors that contribute to the rise and fall of dam levels.
WATCH: Dam levels update
"The first rainfall soaks into the ground and fills depressions like farm dams before it runs off to our rivers and dams.
In order for there to be an increase in dam levels, there would have to be continuous rain over a period of time", read a statement from the utility.
Rand Water said the recent rain will not cause immediate change to Vaal Dam levels as the water does not flow into it directly.
"None of the water we have had in Gauteng goes to the Vaal dam so there will be no immediate effect.
The water either flows towards the Crocodile and Jukskei Rivers or it joins the Vaal River downstream of the Vaal Dam to go towards Bloemhof Dam", said Rand Water.
Residents are being urged to continue to use water sparingly.