Where Cape Town's water comes from
Most of Cape Town's water falls as winter rain on the mountains east of the city and is stored in six big dams. The city shares them with towns and farms.
Updated 4 November 2026
Six big dams, one system
Theewaterskloof, Voëlvlei, Berg River, Wemmershoek and the two Steenbras dams make up the Western Cape Water Supply System. Together they hold about 898 000 megalitres when full. Theewaterskloof, near Villiersdorp, holds more than half of that on its own.
They are run as one system, which is why the City and the national Department of Water and Sanitation report one combined level as well as each dam's.
Why the dams fill in winter
Cape Town has a winter-rainfall climate. Cold fronts bring most of the year's rain between April and September, and the mountain catchments get far more of it than the city does. The dams rise through winter and fall through the dry summer, when use is highest.
That makes the level at the end of winter the one that matters most. It is what the system has to last through summer on.
Who shares the water
The City of Cape Town is the biggest user, but not the only one. Nearby towns, farms and industry draw on the same dams.
Each year, after winter, the Department of Water and Sanitation sets how much the system can supply, based mainly on how full the dams are. The City then decides whether restrictions are needed.
A system under strain
The Western Cape government's 2024 State of the Environment report found the system over-allocated: even when the dams are full, there might not be enough water for every household, farm and business that relies on it. It also found that invasive alien plants are cutting the yield of several dams, Theewaterskloof and Voëlvlei especially.
The City's own climate modelling expects the system's yield to fall by about a quarter over the next 30 years. That is why it is adding water from sources that don't depend on rain: groundwater, purified recycled water and desalination.
Sources
- City of Cape Town: this week's dam levels (capacities)
- Department of Water and Sanitation: Western Cape dam levels, 29 September 2023
- Daily Maverick: Western Cape's inland water resources are in decline (2024)
- City of Cape Town: investing in resilient future water (2022)
- City of Cape Town: water restrictions explained