Capacity share
53.9%
The dominant reservoir — when Theewaterskloof moves, the combined number moves.
Individual dam profile
Theewaterskloof
Theewaterskloof is currently at 75.9%, holding 363.8 of its 479.3 gigalitres of capacity. That is 10.3% below the same week last year (86.2%). Against the same-week long-run average, it sits 1.9% below. Relative to 2017's drought benchmark week, it is 47.8% higher.
75.9% full · Updated 14 Sept 2026 363.8 / 479.3 GL
Role in the system
Theewaterskloof makes up 53.9% of total system capacity and currently holds 54.6% of the stored water — fuller than the system as a whole.
Share of stored water
54.6%
Roughly in line with its share of total capacity.
Location
Near Villiersdorp in the Riviersonderend / Sonderend catchment, eastern Western Cape.
Theewaterskloof in the Western Cape supply system
Big Six dams shown; Theewaterskloof highlighted.
Outer ring = total capacity · Filled area = current level
Background and reference facts
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.
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
Build era
Late-1970s expansion
The dam belongs to the major late-20th-century build-out that expanded regional storage well beyond the older municipal dams.
Sources: Wikipedia · Grokipedia
Usage
Municipal, industrial and irrigation
Sources consistently describe Theewaterskloof as serving Cape Town's municipal supply while also supporting irrigation demand in the surrounding agricultural region.
Sources: Wikipedia · Grokipedia
Storage trend and same-week benchmarks
Theewaterskloof is tracking below the long-run average for this time of year. It sits 10.3% below the same week last year.
Weekly trend (last 2 years)
Currently 6.1% below the same week last year and 5.1% above the long-run average.
Same-week comparison by year
At 78.4%, this week sits 50.3% above the 2017 drought benchmark.
Recent weekly readings
| Date | Level | Storage | Weekly change |
|---|---|---|---|
| 11 Aug 2026 | 78.4% | 376.5 GL | +0.3 |
| 03 Aug 2026 | 78.2% | 375.5 GL | -0.7 |
| 27 Jul 2026 | 78.9% | 378.9 GL | +0.2 |
| 20 Jul 2026 | 78.7% | 377.9 GL | +0.6 |
| 13 Jul 2026 | 78.1% | 375.0 GL | +0.8 |
| 06 Jul 2026 | 77.3% | 371.2 GL | +1.4 |
| 29 Jun 2026 | 75.9% | 364.5 GL | +0.5 |
| 22 Jun 2026 | 75.4% | 362.1 GL | +0.3 |
| 15 Jun 2026 | 75.1% | 360.6 GL | +0.7 |
| 08 Jun 2026 | 74.4% | 357.3 GL | +0.7 |
| 01 Jun 2026 | 73.7% | 353.9 GL | +1.1 |
| 25 May 2026 | 72.6% | 348.6 GL | +0.7 |