A pilot project launched in Benoni last week is testing whether recycling water from showers, kitchens and laundries close to where it is generated could offer a practical way to ease pressure on South Africa’s increasingly strained water infrastructure.
The Low-Tech Water Project, a collaboration between the Zurich University of Applied Sciences (ZHAW) in Switzerland, Stellenbosch University and Manger Care Centre in Benoni, builds on more than seven years of research into low-energy water treatment systems designed for communities where conventional infrastructure is under pressure or unavailable.
It aims to demonstrate that decentralised water reuse systems can safely recycle wastewater for uses such as toilet flushing, irrigation and laundry without the need for complex treatment plants or extensive municipal infrastructure.
The approach challenges the conventional use-once-and-discard model that dominates urban water management.
“Our traditional approach to water follows a linear model: we extract it, use it once and discharge it,” said Dr Devi Bühler, the project’s lead researcher at ZHAW.
“We believe it is time to rethink that approach. Water is part of a natural cycle and our challenge is to provide safe water and sanitation services while protecting the ecosystems that sustain them.”
The system relies on naturally occurring biological processes rather than chemicals or membrane filtration, produces little waste sludge and requires relatively little maintenance or energy. The proponents say that, once fully optimised, it could even be powered by a modest solar installation.
The new pilot facility treats greywater from showers, kitchens and laundry separately from blackwater from toilets. By treating each stream according to its characteristics, water can be treated to the quality required for its intended use, rather than providing drinking water quality where it is not required.
While the technology is being tested at Manger Care Centre, which runs reintegration programmes for homeless people, Bühler said the broader ambition was to explore whether decentralised reuse systems could complement conventional municipal infrastructure in communities facing growing water scarcity and ageing infrastructure.
According to the latest Green Drop report, 396 (47%) of the 848 municipal wastewater systems assessed are in a critical condition, up from 39% in 2022.
The Blue Drop progress assessment, which evaluates drinking water quality, found that nearly 38% of drinking water systems fall outside the low-risk category, including 185 high- or critical-risk systems, of which 79 are in outright crisis, exposing communities to unsafe or unreliable drinking water.
For Bühler, the project is about more than demonstrating a new treatment technology. It is focused on exploring whether decentralised water reuse could become part of the country’s response to mounting water scarcity and failing infrastructure.
South Africa faces two interconnected challenges, she said. A large proportion of the population was not connected to centralised sewer systems. In rural areas, extending sewer infrastructure was often not economically viable, while in informal settlements conventional sewer systems were often not feasible.
That meant many people relied on decentralised sanitation systems that often did not provide adequate treatment or opportunities for water reuse.
While centralised water and sanitation systems had been fundamental to improving public health and remain indispensable, Bühler argued that they also had inherent limitations.
“They are capital intensive, require extensive infrastructure and are not always flexible enough to adapt to growing or shrinking populations or changing water availability. Their operation also depends on significant financial, technical and institutional capacity. Many wastewater treatment plants are operating below their intended performance.”
The project is not necessarily about replacing municipal infrastructure but about complementing it with decentralised solutions where they offer advantages.
“We are investigating how wastewater can be treated close to where it is generated and reused locally. This can reduce demand for drinking water while increasing resilience and resource efficiency.
“In urban areas, this can reduce pressure on existing water and sewer networks. In areas without adequate infrastructure, it can provide safe and dignified water and sanitation services through decentralised or fully off-grid systems.”
The Benoni facility is intended to function as a “living laboratory”, allowing researchers to evaluate not only whether the technology consistently produces safe, reusable water but also how well it performs under everyday conditions.
Over the coming months, they will monitor water quality, maintenance requirements, operating costs and energy consumption while working with staff and beneficiaries at Manger Care Centre to understand how the system fits into daily life. The first comprehensive technical and operational results are expected by the end of the year.
At its current design capacity of 2 000 litres a day, energy consumption is about 4.5 kWh a day, or 2.3 kWh a cubic metre. This is expected to reduce further to 1.0 kWh/m³ through ongoing optimisation. “This energy can easily be supplied by an on-site solar system at reasonable cost,” she said.
Although the technology is being validated, Bühler believes engineering is no longer the biggest challenge facing decentralised water reuse.
“The technological barriers are probably the smallest. The purpose of this pilot is to validate and optimise the final components of a technology that has gone through several development stages.
“We will undoubtedly continue improving the system but I don’t see the technology itself as the main obstacle to wider implementation.”
The bigger challenges were regulatory and institutional, she said. While South Africa had legislation relevant to decentralised water reuse, it was fragmented and, in some areas, not sufficiently developed for those types of systems.
“Developers and municipalities therefore often face uncertainty about approval pathways, water quality requirements and responsibilities. Clearer and more consistent regulation would provide confidence both for regulators and for those implementing these systems.”
There are also broader governance hurdles. “In some situations, decentralised systems are actively encouraged, particularly in rural areas or locations where extending conventional sewer infrastructure is not technically or economically feasible.”
In other areas, there can be competing interests. Municipalities are responsible for providing water and sanitation services and often rely on water tariffs as an important source of revenue.
“Decentralised reuse systems can reduce water consumption and wastewater flows, which means the incentives are not always fully aligned. To realise the full potential of decentralised water reuse, it must be evaluated from a broader societal perspective rather than only from the perspective of an individual utility or municipality,” Bühler said.
“The question should not simply be who sells the water but what delivers the greatest public benefit in terms of water security, environmental protection, resilience and long-term infrastructure costs. That requires an enabling policy framework and incentives that recognise the value these systems can provide.”