Icebergs a way to water the Cape
A single iceberg could provide about 130-million litres of water daily for a year
The doomsday scenario of Cape Town’s taps running dry has been averted for 2018.
Its 4-million residents have slashed their water consumption and supply was cut off to farmers, but the crisis confronting the country’s second-biggest city is far from over.
The city’s six main dams are now on average just 21% full, almost 2 percentage points less than they were a year ago.
If winter rains disappoint and a three-year drought does not break, the threat of Day Zero will loom large again in 2019.
Among the options being considered to meet the water shortfall are to build more desalination plants, recycle water, use more ground water and use Antarctic icebergs.
Salvage expert Nick Sloane has proposed using tugboats and a tanker to guide an iceberg more than 1,000 nautical miles from the waters of the Antarctic to Saldanha Bay, where it could be run aground and harvested. A single iceberg could provide about 130-million litres of water daily for a year.
The authorities in Cape Town have introduced higher tariffs, usage restrictions and a hard-hitting advertising campaign. Collectively, these have driven consumption down to 519-million litres a day, from 1.2-billion litres three years ago. But it remains higher than the city’s target of 450-million litres. Further price increases are in the offing, and the city intends installing more devices that restrict the flow to households that exceed their daily quota of 50 litres a person. This may curb demand, but many households and businesses have limited scope to save more.
Three temporary small-scale desalination plants that will produce 16-million litres of water a day are nearly complete. The city has steered clear of big plants because of high costs, environmental concerns and the risk that they will not be needed if there is adequate rainfall.
The metro is considering whether to build a facility that could provide 150-million litres of water a day from 2021, while another 20-million litre plant that could be operational from 2020 is also being considered.
The city intends building a temporary sewage recycling plant that would yield 10-million litres of water a day from late in 2018. It is also thinking of building a permanent facility that could process up to 90-million litres daily from 2020.
The estimated cost of making waste water drinkable is about R7.50 per 1,000 litres — just more than half the cost of effective desalination — because the plants use less electricity and would not require extensive marine works, according to the City of Cape Town’s water outlook 2018 report.