Current level
75.9%
363.8 of 479.3 GL in storage · weekly change -2.5%.
Dam directory
The Big Six, with context
Live levels tell you where the system is today. These reference profiles add the slower facts: when each dam was built, what kind of structure it is, and why it matters in the wider Cape Town supply system.
75.0% combined storage · 6 major dams tracked
Updated 14 Sept 2026
At a glance
| Dam | Built | Type | Capacity | Now |
|---|---|---|---|---|
| Theewaterskloof | 1978–1980 | Earth-fill dam | 479.3 GL | 75.9% |
| Voëlvlei | 1952 | Earth-fill dam | 158.6 GL | 58.6% |
| Berg River | 2009 | Concrete-faced rockfill / modern large dam project | 127.1 GL | 91.0% |
| Wemmershoek | 1953–1957 | Rock-fill dam | 58.8 GL | 88.8% |
| Steenbras Lower | 1918–1921 | Concrete gravity-arch dam | 33.9 GL | 46.2% |
| Steenbras Upper | 1977 | Earth-fill dam | 31.9 GL | 83.3% |
Theewaterskloof
Theewaterskloof is the anchor reservoir of the Western Cape Water Supply System, sitting near Villiersdorp on the Sonderend River with by far the largest storage footprint in the Cape Town supply mix.
System share
53.9%
Share of total Big Six capacity — larger dams shift the citywide number more when they rise or fall.
Why it matters
Largest dam in the system
It is the single most important storage asset in Cape Town's supply system, so moves in Theewaterskloof heavily influence the combined system number.
Sources: Wikipedia · Grokipedia
Voëlvlei
Voëlvlei is an off-channel style storage asset near Gouda that turned a natural depression into one of the system's largest reservoirs and later became more deeply integrated with Berg River transfers.
Current level
58.6%
92.9 of 158.6 GL in storage · weekly change -2.9%.
System share
17.8%
Share of total Big Six capacity — larger dams shift the citywide number more when they rise or fall.
Origin story
Built on a natural depression
Voëlvlei was created by enlarging an existing lake-like depression, which gives it a different character from the steep-walled mountain dams in the system.
Sources: Wikipedia
Berg River
Berg River Dam is the newest of the Big Six and the clearest modern-era augmentation project in the system, designed to capture winter rainfall for later summer supply.
Current level
91.0%
115.7 of 127.1 GL in storage · weekly change -1.3%.
System share
14.3%
Share of total Big Six capacity — larger dams shift the citywide number more when they rise or fall.
Wemmershoek
Wemmershoek is one of the older mountain dams in the Cape Town system, built in the 1950s after decades of planning around the valley's water-supply potential.
Current level
88.8%
52.2 of 58.8 GL in storage · weekly change -9.3%.
System share
6.6%
Share of total Big Six capacity — larger dams shift the citywide number more when they rise or fall.
Long planning tail
Studied since the 1880s
Hydrographic surveys flagged the valley for water supply long before the dam was eventually built, making Wemmershoek a story of very long-term municipal planning.
Sources: Wikipedia
Steenbras Lower
Steenbras Lower is one of Cape Town's foundational 20th-century dams, part of the original Steenbras scheme that brought mountain water into the city through tunnels and pipelines.
Current level
46.2%
15.7 of 33.9 GL in storage · weekly change -7.4%.
System share
3.8%
Share of total Big Six capacity — larger dams shift the citywide number more when they rise or fall.
Foundational infrastructure
Part of Cape Town's early bulk-water era
The original Steenbras scheme predates most other dams in the current system and shows how long Cape Town has relied on mountain transfer infrastructure.
Sources: Wikipedia
Steenbras Upper
Steenbras Upper is the younger partner to Steenbras Lower and doubles as the upper reservoir in Cape Town's pumped-storage power scheme.
Current level
83.3%
26.6 of 31.9 GL in storage · weekly change -13.6%.
System share
3.6%
Share of total Big Six capacity — larger dams shift the citywide number more when they rise or fall.
Dual-purpose asset
Water + power infrastructure
Steenbras Upper is unusual in the Big Six because it also functions as the upper reservoir for the Steenbras pumped-storage hydroelectric scheme.
Sources: Wikipedia