The GCR receives most of its potable/piped water from outside the region and discharges it as wastewater downstream, mainly outside the city-region. The main source of untreated water for Gauteng is the Vaal Dam, located 56km south of Johannesburg. The catchment area of the dam is approximately 38 500 km2. The largest part of the Vaal Dam catchment lies in the Free State province (60%) with the rest lying in Gauteng and Mpumalanga provinces.
Rand Water supplies bulk water to municipalities, which then transfers water to various sectors and economic participants:
- 92% of the water supply processed by Rand Water is transferred to municipalities from where it is conveyed to domestic, industrial, commercial and other end users.
- The remaining 8% is supplied directly to the mining industry. *
- The top three consumers of this water are the three metropolitan areas in Gauteng namely, Johannesburg, Ekurhuleni and Tshwane, which together consume 75% of water supplied by Rand Water. *