Miscellaneous / Ten (10) to Inspire / Western Cape

Cape Town Water Supply – What is the City Doing?

Updated Thursday, 18 June 2020

The water supply in Cape Town is on everyone’s lips.

Particularly now that the crisis is declared a national state of disaster (freeing up ‘special funds’ through Treasury to deal with the drought in multiple provinces).

Water dominates dinner table conversation, people chat about water supply whilst in queues, and #DayZero (though no longer a threat for 2018) continues to pepper South Africans’ conversation on social media.

Capetonians’ need for reassurance is high as the city continues with level 6b water restrictions to avoid queues for water.

It’s 50 litres per person, per day, and hope that it rains soon!

To lessen the rumour and fear that surround Cape Town’s water supply we give you a bird’s eye view of what the City is doing to recover the situation (other than getting everyone to dramatically curb their usage).

The dams that feed Cape Town – where are they?

Cape Town’s water at a glance:

  1. There are 44 dams in the Western Cape
  2. Most of Cape Town’s water comes from the Riviersonderend-Berg River Water Scheme, which makes up the biggest part of the Western Cape Water Supply System (WCWSS)
  3. This scheme captures the flow of 3 rivers – Sonderend River, Berg River and Eerste River
  4. It’s water is held in 6 major dams (keep scrolling to find out which)
  5. They hold 99.6% of Cape Town’s water
  6. These dams lie in the mountains east of Cape Town
  7. The other 8 minor dams (Kleinplaats, Woodhead, Hely-Hutchinson, Land-en-Zeezicht, De Villiers, Lewis Gay, Victoria, Alexandra) store only 0.4% of the water supply
  8. Collectively all 44 dams can hold as much as 1870.4 million cubic metres of water
  9. The average dam level across the province is lower than 22% as we write this blog
  10. The last 10% of a dam’s water is almost impossible to use

Day Zero is no more for 2018* but no long showers just yet

*this is ONLY IF Capetonians use less than 500 million litres a day! (less than 50 litres each). If the city uses 600 million litres/day, or more, day zero could easily move back into the picture.

The City of Cape Town provides a weekly water dashboard for you to keep track – on ‘Day Zero water dashboard’.

The water picture for Cape Town as of 14 March 2018…
Cape Town Water Supply

The 6 major Western Cape dams in the Riviersonderend-Berg River Water Scheme

1 – Theewaterskloof Dam

Theewaterskloof Dam is the Western Cape’s cornerstone dam (most of the city’s water supply comes from this dam) and it’s virtually empty (under 11%).

It’s a very natural looking earth-fill dam close to Villiersdorp where it lies in a perfect position to catch water from the Kogelberg, Kleinrivier and Hottentots-Holland mountains. We need only one millimetre of rain in the area to catch 500-million litres, of which between 9-15% actually reaches the dam. Usually there is enough rainfall in the area to fill the dam 17 times a year.

2 – Wemmershoek Dam

Wemmershoek is another earth-fill dam in amongst the mountains between Franschhoek and Paarl in the Winelands of the Western Cape.

In a bid to save a 1% annual consumption of the dam’s water 50 hectares of alien trees and vegetation at the dam have already been cut with more to follow. Its water level is below 46%.

3 and 4 – Steenbras Dams (upper and lower)

Upper and lower Steenbras lie on the Steenbras River, above Gordons Bay, in amongst the mountains through which one travels over Sir Lowry’s Pass.

You can catch a glimpse of upper Steenbras (named for the fish of the same name) on the latter part of the pass from Cape Town – close to Elgin (the dam on your right with a tiny bit of it to your left as you come around the last bend of the downward sweep of the pass).

You’ll notice how full it looks. Some say misleadingly so. But it turns out that the upper dam (the full part you see when driving) forms part of a hydroelectric plant, and the water gets pumped up here out of the lower dam as part of the process to generate electricity.

It’s also a feed through area for the Palmiet pumped storage scheme, which temporarily holds water from the Palmiet River in the dam.

5 – Voëlvlei Dam

Voëlvlei is the second largest dam supplying Cape Town, Overberg, Boland, West Coast and Swartland. It is a natural large depression that functioned as a dam for thousands of years, only getting a wall in 1971 when the dam was extended into neighbouring farms near Gouda (the land was expropriated by the nationalist government).

Now a project, which aims to increase the water supply to the dam, is on fast-track. Originally scheduled only for 2024, the scheme to pump winter rainfall from the Berg River to the dam could start as early as 2019.

6. Berg River Dam

The Berg River Dam, on the river of the same name, only came online in 2009 making it the youngest dam in the Cape Fold Mountains between Pniel and Franschhoek.

Interestingly, it was a private sector-funded dam, designed according to World Commission on Dams’ guidelines, with the sale of water from TCTA (the dam’s owner) to the Department of Water and Forestry functioning as a means of reimbursement.

Can the dams atop Table Mountain help at all?

Despite being full of sparkling blue water, the dams atop Table Mountain are said to supply only 2% of Cape Town’s water needs so won’t help the crisis.

What’s the City doing to boost the Cape Town water supply?

Water Augmentation Projects

The 7 water projects that will help SAVE Cape Town

The City has eight alternative water source projects on the burner.

Seven of them, according to GroundUp, are behind schedule. Despite this, six of the projects will feed water into Cape Town’s system before the former Day Zero deadline of 9 July.

Project 1: the Strandfontein small-scale emergency desalination plant

This small-scale desalination plan is over 70% complete already, on track to supply 2-MLD (Millions of Litres Per Day) into the water system by the later half of March, and 7-MLD by the first half of May.

Project 2: the Monwabisi small-scale emergency desalination plant

Monwabisi is also more than 70% complete, due to add 2-MLD by the first half of April, and a further 7-MLD by the second part of May.

Project 3: the V&A small-scale emergency desalination plant

The only project on schedule –  80% complete – the V&A plant will add 2-MLD this month still.

Project 4: the Cape Flats aquifer groundwater abstraction project

Around 60% of the Cape Flats abstraction project is complete, with up to 83-MLD to feed into Cape Town’s water by June.

Project 5: the Atlantis aquifer groundwater abstraction project

This project already pumps 12 MLD, despite being behind schedule. It anticipates a further 20-MLD yield between May and October this year.

Project 6: the Table Mountain Group aquifers

Exploratory drilling began on this project last November and the City hopes to produce 50-MLD in this way. Environmental concerns presented by 5 leading UCT academics may stall the project.

Still to come…

Cape Town Harbour desalination plant

The City has yet to choose where to build this project, but they’re anticipating 100-150 MLD/day.

Temporary Zandvliet water recycling project

This is only 55% complete but will produce a further 10 MLD when it comes into production, hopefully in June 2018.

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