Aquifer drilling on the Cape Flats. Photo courtesy of CoCT
The City of Cape Town needs to spend R2 billion on building and upgrading water infrastructure, and developing new water sources, to ensure water security for the next decade.
Delays in implementing the Water Resources Plan will increase the likelihood of water restrictions as demand for scarce water resources is closely monitored over the next 12 months.
This is according to the city's Department of Water and Sanitation's March 2024 Water Outlook report, released this week, which also highlighted the need to fast-track the New Water Programme (NWP), which aims to diversify water sources to ensure the sustainability of future supplies.
Proposed diversification of water sources includes plans to develop a desalination plant near Cape Town's port, recycle wastewater, drill new boreholes and extract groundwater from aquifers.
Water experts this week welcomed the plans outlined in a report that also highlighted risks facing water security, including climate change and weather hazards such as droughts and floods that threaten surface water quality, and increasing demand, but warned that more attention should be paid to the environmental impacts of plans to diversify water sources.
The report said initial studies had shown that the city's infrastructure stabilisation programme, which involves upgrading infrastructure and building new capacity, would require R2 billion in funding over the next 10 years, an amount already built into the city's budget.
These projects include the rehabilitation of major pipelines, some of which are over 100 years old, and the renovation of five major water treatment plants to operate at their full designed capacity, which is essential to meet the demand for an additional 300 megalitres (ML) per day of production by 2035. Some plants are currently operating at 75% capacity.
The target of an additional 300ML per day of supply is in line with the Cape Town Water Strategy (2019), which was implemented after overcoming the “Day Zero” drought from 2017 to 2019. At the time, Level 7 water restrictions meant that the city's water supply would be cut off due to water shortages.
Since then, the report noted, Cape Town's water demand has risen steadily from a low of 500 million litres per day in June 2018. At its peak in February 2024, demand exceeded 1,000 millilitres per day.
The recovery of water demand after a zero-day drought outpaces the population growth rate of about 2 percent per year from 2011 to 2022, according to the report.
“Thus, recovery is not yet complete (more likely), population statistics are underestimated, or system losses are increasing (less likely). The City will closely monitor over the next 12 months whether water demand growth approaches the rate of population growth,” the report said.
“If demand growth continues to exceed projections, the timing of new water plans and planning assumptions may need to be revised or higher risk of restrictions may need to be accepted.”
As part of the R2 billion investment, additional infrastructure will also be built to ensure the flexibility and robustness of the bulk water system. Some of these projects are expected to “address identified backlogs, capacity challenges and constraints”, with work due to commence in the 2024/2025 financial year.
The city's Bulk Water Master Plan emphasizes that non-surface water options, particularly desalination and water reuse, will dominate future water resources, according to the report.
National Treasury’s Government Technical Advisory Centre is providing trade and expert advisory services to the city to determine the best implementation for developing a permanent desalination plant.
The advisers considered the feasibility of the proposed site, an undeveloped piece of land at the junction of the R27 and N1 next to the Bidvest Container Depot near the port, and compared it with alternative sites.
“The transaction adviser considered various mechanisms that could be used to implement this plan and assessed the City's internal capacity to implement and operate the desalination plant in accordance with section 78(1) of the Municipal Systems Act (MSA),” the report said.
The results of the assessment were shared with City Council, which approved in March 2024 to proceed with a detailed feasibility study of alternatives for building and operating the plant.
“Transaction advisers are currently busy conducting a detailed feasibility study of alternative options (including a possible public-private partnership). The detailed feasibility study will also include a financial assessment of various delivery mechanisms,” the report noted.
The Environmental Impact Assessment process has also begun and the project is on track to deliver around 70 megalitres per day by 2030. Other potential desalination sites on the west coast, including Melkbosstrand and Vitzants, are also being evaluated.
The Water Reuse Strategy Study identified 10 wastewater treatment works (WWTWs) that could potentially recycle water for direct potable reuse (DPR) and indirect potable reuse (IPR), but excluded a further 16 because they had a high proportion of industrial wastewater, the WWTWs were too small to be viable, or all treated wastewater was already being used for other purposes. The 10 sites are located in Green Point, Hout Bay, Wildevourvlei, Cape Flats, Mitchell's Plain, Bellville, Athlone, Potsdam, Fisanteclair and Makassar.
Groundwater is a key component of the City's water resource diversification strategy and a vital resource for drought-resilient development, the report noted. Over the last year, the City has continued to develop and operate three groundwater schemes: the Table Mountain Group Aquifer (TMG), the Cape Flats Aquifer (CFA) and the Atlantis Aquifer, including drilling more than 10 boreholes.
The report warned that delays in implementing the city's NWP “increase the likelihood of water restrictions being imposed and the city will not be able to deliver 300 megalitres of water a day by 2030”.
“Concerns over ageing infrastructure and potential changes to raw water quality may lead to restrictions in the short to medium term. Addressing these risks could take several years,” the report said.
“Water demand growth will need to be closely monitored over the next 12 months. If demand growth does not abate, plans may need to be brought forward or target supply guarantees may need to be adjusted,” the report warned.
“It's good that Cape Town has learned from the Day Zero debacle,” said Mike Muller, a development expert at Wits University.
“At that time we relied too much on water conservation and the development of new supply infrastructure was not a priority. The current program to develop infrastructure to increase supply is an important complement to ongoing efforts to improve water distribution and promote water use efficiency. This is the only way to ensure resilience to climate variability and change,” Mueller said.
Associate Professor Kevin Winter from the University of Cape Town's Future Water Institute said managing future water supplies was much more complex than it was 10 years ago.
“There is a lot of uncertainty about how changes in climate and weather will affect water supplies. Additionally, the city's population is growing by 1.6-2 percent, effectively adding one million people per decade. Lifestyle choices and habits increase population and per capita water use, especially during long, dry summers,” Winter said.
“The city is moving in the right direction with plans to expand water services, advance pipeline replacement plans and ensure large infrastructure facilities are performing to their designed capacity,” Winter said.
“Water and sanitation managers must be anxious about how to raise the capital and operating budgets to meet the immediate obligation to provide at least 300 million litres per day by 2030. What's worse, if drought suddenly hits again much sooner than expected, the city will struggle to keep its master plan and implementation programme on track,” he said.
Winter said the report was “forward-looking and unblaming.”
Precious Vieira, a senior lecturer at Wits University's school of civil and environmental engineering, said the report showed the city was “generally” well prepared to meet future water needs.
“In my view, ironically, the biggest risks relate to the environmental impacts of these new proposed methods of ensuring water security. In the same way that the report mentions the financial costs of infrastructure development and so on, I believe the report should have been more transparent and direct about the environmental costs of the plans,” Vieira said.
“I'm sure the city's planners and advisers are considering these points and it would be great to see them featured in the Outlook Report.”
