Why desalination must be central to South Africa’s water future

South Africa is widely described as a water-scarce country. The phrase appears so often in policy discussions, academic literature and public discourse that it has become accepted as an almost unquestioned truth. The country receives relatively low average rainfall, and large parts of the interior are semi-arid, while climate change is intensifying drought cycles and rainfall variability.

Yet this characterisation, while broadly accurate, deserves deeper scrutiny. South Africa indeed faces significant freshwater constraints, but it is also a country with about 3,500km of coastline, bordered by both the Atlantic and Indian oceans. In this context, a more probing question emerges: is water scarcity a fixed natural condition or is it partly the result of a failure to fully harness the resources available to us? The answer increasingly points towards a strategic expansion of seawater desalination.

Desalination, the process of removing salts and minerals from seawater to produce potable water, has undergone profound technological transformation over the past three decades. What was once considered prohibitively expensive and energy-intensive has become a mainstream component of water security strategies around the world.

Countries with far fewer natural advantages than South Africa have already embraced desalination as a cornerstone of water security. Singapore, historically dependent on imported water, has built a diversified system combining desalination, wastewater recycling and stormwater capture. Australia invested heavily in desalination during the millennium drought to safeguard the water supplies of cities such as Perth, Sydney and Melbourne. These countries demonstrate that water scarcity can be managed through technological innovation and strategic infrastructure investment.

South Africa has similar opportunities. Nearly 40% of the country’s population lives in coastal provinces. Major urban and economic centres such as Cape Town, Nelson Mandela Bay, eThekwini and the rapidly expanding coastal corridors of the Western and Eastern Cape are already experiencing growing pressure on traditional surface-water systems. Population growth, urbanisation, climate variability and ageing water infrastructure are straining water resources.

Climate-resilient, drought-proof

The 2018 “Day Zero” crisis in Cape Town provided a stark illustration of how vulnerable urban water systems can become when rainfall-dependent sources are pushed to their limits. This episode revealed how fragile conventional water supply systems can be in a changing climate.

Unlike rainfall-dependent dams and rivers, desalination provides a climate-resilient and drought-proof supply. The ocean does not run dry during drought cycles. By integrating desalination into long-term national water planning, South Africa could create a strategic buffer against future water shocks.

Crucially, desalination should not be viewed as a silver bullet. Water security requires a diversified portfolio of solutions. Infrastructure maintenance, reduction of non-revenue water losses, wastewater reuse, groundwater development and improved catchment management must all remain central pillars of national policy.

South Africa already has examples of how unconventional water sources can strengthen national supply. The work of the Trans-Caledon Tunnel Authority in treating acid mine drainage demonstrates how a major environmental liability can be transformed into a valuable water resource. In many respects, the treatment of acid mine drainage is conceptually similar to desalination since both involve advanced processes that remove harmful minerals and contaminants to convert unusable water into potable supply. This experience shows that South Africa is already applying such technologies on a limited scale, and the next logical step is to expand these capabilities to include seawater.

Through advanced treatment plants in the country’s mining basins, polluted mine water is purified and returned to the water system, contributing significant volumes to urban supply. This experience shows that innovation and infrastructure investment can convert previously unusable water into a reliable supplementary source. The lesson is clear: when technology, governance and investment align, water challenges can be transformed into opportunities.

Case strengthened

Climate research further underscores the need to diversify water sources. Studies supported by the Water Research Commission show that the cyclical patterns of the El Niño-Southern Oscillation produce uneven rainfall across South Africa, with some regions experiencing drought while others receive above-average rainfall. Coastal towns such as George and Plettenberg Bay can experience El Niño-type drought conditions, while inland provinces such as Limpopo, Mpumalanga and Gauteng may simultaneously experience wetter La Niña conditions. This uneven climate reality strengthens the case for developing desalination capacity along the coastlines of KwaZulu-Natal, the Eastern Cape, the Western Cape and the Northern Cape.

Encouragingly, South Africa already has significant research capacity in desalination technologies. Universities and research institutions have been actively exploring desalination and alternative water sources for years. The Water Research Commission has funded extensive work in this field. Stellenbosch University has also participated in innovative pilot projects exploring the integration of renewable energy and desalination. In 2018, researchers partnered with the Hessequa Municipality to establish South Africa’s first solar-powered desalination plant in the coastal town of Witsand.

More broadly, national research initiatives are increasingly focusing on alternative water sources, including desalination, as part of South Africa’s long-term water innovation strategy. The government’s Water Research, Development and Innovation Roadmap explicitly identifies desalination, water reuse and improved groundwater use as key pathways to strengthen water security in a climate-constrained future.

New research centres are also expanding the country’s scientific capacity in water innovation. Partnerships between universities and the Water Research Commission, such as the establishment of the Arid Region Water Research Centre at Sol Plaatje University, are helping to develop new technologies and policy solutions for water-stressed environments. These developments show that South Africa is not starting from zero. The country already has the scientific expertise, engineering capacity and institutional frameworks required to advance desalination.

Compelling cases

One of the key concerns often raised about desalination is cost, particularly the energy required to power reverse-osmosis systems. However, technological improvements and the rapid growth of renewable energy are changing this equation. Solar and wind power, both abundant along South Africa’s coastline, can significantly reduce operating costs while lowering the carbon footprint of desalination plants.

In addition, water infrastructure can also support energy resilience. Integrating hydropower into dams, pipelines and large-scale water treatment systems can reduce dependence on the national electricity grid and lower operating costs. As desalination facilities expand, coupling them with renewable energy and hydropower generation could make them far more financially sustainable over the long term.

This presents a particularly compelling opportunity for South Africa, where coastal regions such as the Western Cape and Northern Cape have some of the world’s best solar and wind resources. By aligning desalination infrastructure with the expansion of renewable energy, the country could create a new generation of climate-resilient water systems.

The economic case is equally compelling. Water security underpins virtually every dimension of national development. Reliable water supply supports agriculture, industry, tourism, mining, energy production and urban growth. Conversely, water shortages impose severe economic costs, disrupt investment and undermine social stability. In this sense, desalination is not merely a water project. It is also a strategic economic investment.

The long-term cost of water insecurity – lost economic output, infrastructure damage, emergency interventions and declining investor confidence – can far exceed the capital required to build resilient water infrastructure. History shows that nations that thrive are those that transform natural constraints into strategic advantages.

Given the scale of investment required, South Africa should also pursue continental and international partnerships in desalination technology, financing and knowledge exchange. Institutions such as the Trans-Caledon Tunnel Authority, currently being integrated into the South African National Water Resources Infrastructure Agency, could be mandated to coordinate this programme nationally, replicating the successful model already used in managing acid mine drainage treatment projects.

Instead of asking whether we have enough water, we should ask a more ambitious question: how boldly are we prepared to invest in securing it?

The government, industry, researchers and investors must work together to accelerate desalination feasibility studies, develop coastal pilot projects and integrate desalination into long-term national water planning. Universities and engineering institutions should expand research into energy-efficient desalination technologies tailored for South African conditions. Financial institutions and development partners should recognise water infrastructure as a critical investment in economic stability.

As South Africans, we must expand our imagination. We may be a water-scarce country, but our coastline stretches for thousands of kilometres. The oceans that surround us are vast and enduring. With vision, innovation and investment they can become a cornerstone of South Africa’s water security. DM

Ramateu Monyokolo is chairperson of the Rand Water Board and the Association of Water and Sanitation Institutions of South Africa.