Popular Mechanics (South Africa)
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We need to talk about the water crisis
There are a few things you need to know about the water crisis in Cape Town but first a little history. The city’s original dam, Woodhead Dam on Table Mountain, was completed in 1897 and augmented by the Hely-hutchinson Dam in 1904. This 954 megalitre (954 000 000 litres) bulk storage was enough to service the city and surrounds until the Steenbras Dam came online in 1921 in the mountains above Gordon’s Bay, along with its 64 kmlong 750 mm cast iron pipeline to feed the Mother’s ever-growing demands. Water was originally stored in the Molteno reservoir in Oranjezicht but increased supply forced the construction of additional piping and storage at the Newlands Reservoir. This project was so wildly successful and expensive that the independent municipalities of Cape Town, Claremont, Green Point, Sea Point, Kalk Bay, Maitland, Mowbray, Rondebosch and Woodstock banded together as the Greater Cape Town Municipality to collectively contain this beastly undertaking. Wynberg and Constantia at this point were fed by the Victoria, Alexandra and De Villiers dams since 1896 but soon joined in to benefit from the surplus.
In 1977, the Steenbras Upper Dam (the bit you see from the N2 when you drive up the Sir Lowry’s Pass) was completed. The first pumped storage scheme in Africa doubled the dam’s overall capacity and is linked to the Rockview Dam to benefit from the Eskom and Department of Water and Sanitation-owned Palmiet Pump Storage Scheme when needed.
Wemmershoek Dam and its clay wall was the second dam to be built outside of Table Mountain area and was completed in 1957. This project is significant because it is the largest single storage facility owned by the city (double the capacity of Steenbras Lower) and its dam wall combination of clay and rock embankment was, at the time, a little more than half the cost of a concrete retainer. Water from this dam is also of a very high quality and requires little treatment.
Voëlvlei Dam was built by DWS and completed in 1971. The dam is fed by canal diversion of the Klein Berg, Leeu and Twenty-four rivers from the Porterville and Tulbagh mountains. While the dam was built by national government, treatment and piping infrastructure was constructed by the COCT. Simon’s Town is primarily fed by the Kleinplaats and Lewis Gay dams but was connected to the City of Cape Town water system in 1997.
That brings us to the jewel in the Cape Town water supply crown. Theewaterskloof Dam is the seventh largest in South Africa (480 250 Ml, bigger than all 13 other Cape Town dams combined and is interconnected to the city and the Wemmershoek and Berg River dams by 30 km of tunnels running through the Franschhoek, Groot Drakenstein and Stellenbosch mountains. Water is fed to the Kleinplaas Balancing Dam in the Jonkershoek valley and then into the main supply.
Of Cape Town’s 14 dams, the three largest – Theewaterskloof, Voëlvlei and Berg River – are all owned by the national government. This is important because the provincial narrative shifted quickly to questioning the State in the face of the worsening crisis.
As the city continues to grow and the subsequent demand for fresh water also increases there are other water sources needed but no suitable land is available for a new dam.
The current option being tabled is a diversion of winter water from the Berg River to the Voëlvlei Dam (Berg River-voëlvlei Augmentation Scheme, or BRVAS) and transfer of water from the Breede River to the Berg River. With the BRVAS construction costs estimated at R277 million to add 23 million cubes of water per annum to the Voëlvlei storage it seems like the perfect solution. There’s just one problem: there hasn’t been sufficient rain in the crucial catchment areas and the current trend is sharply downward.
According to 2011 census data, the City of Cape Town provides water and sanitation services to 3,74 million people. Within this network there are nearly 650 000 properties and approximately 156 000 informal households. Those 650 000 houses consume around 55 per cent of the drinking water, a 2,1 per cent decrease since 2014/15. Muchmaligned informal settlements, however, accounted for a mere 3,6 per cent of the total water usage in the 2016/17 period. However, the data doesn’t really matter because it’s all estimates.
It’s been the biggest criticism of the City of Cape Town’s approach to dealing with the drought. The initial knee-jerk reaction was to paint the citizenry as the biggest culprit in an aggressive drive to save water through self-policing and public shaming. With average domestic use calculated between 200 and 600 litres per day – or between 72 and 216 kl per annum – the provisioned water is more than sufficient when the weather operates as scheduled. But outdated census data (reported consumption numbers are calculated over the two-year period from 2014/15 to 2016/17) and shallow consumption data (an overwhelming percentage of meter readings are estimates because of understaffing and a lot of water is wasted to restore service after leaks are repaired) make many of the measures seem untrustworthy.
In short, the City of Cape Town doesn’t have reliable data to substantiate many of the consumption claims and by not actively policing the installation of water features since starting water restrictions in 2015, or by not employing enough operations technicians to deal with a creaking reticulation system, the city exacerbated the problem. We are told that the immediate solution is desalination because the rains aren’t expected to refill the dams and a 95 per cent reliance on that system isn’t sustainable with the long-term effects of climate change.
Israel, a country of an estimated 8,8 million people is presented as the leader in desalination technology because it went from drought to a state of water surplus. In 2008, the Sea of Galilee, Israel’s primary water source, was weeks away from the “black line” the point of no return for saltwater infiltration and boreholes were being dug up to 500 metres deep to chase the retreating water table. Day Zero was looming.
The Israeli government started installing low-flow toilets and showerheads in 2007 and, through innovative water treatment, reached 86 per cent waste-water recapture to be used for irrigation. Currently, desalination accounts for only 55 per cent of potable water and future plans for brine – seawater desalination’s biggest headache because of the damage it can do to ocean ecology – disposal is a canal running across neighbouring Jordan to replenish the Dead Sea.