Water reuse can be an effective way to supplement the water needs of growing cities. Even in the midst of record breaking droughts, this alternative can have meaningful impact once it overcomes public misperceptions and investment barriers. USAID and its partners are helping South Africa encourage greater understanding of this promising approach for strengthening urban water security in the face of growing water scarcity.
Imagine that the drought-stricken city of Cape Town, South Africa, had ready access to an additional water supply—enough to satisfy nearly half of the city’s daily demand for drinking water.
Now imagine that this water source is not only of higher quality than water from the city’s reservoirs, but also that it would reduce marine pollution along Cape Town’s famous beaches and use less energy than seawater desalination.
This is not just a water utility manager’s dream. Rather, it represents a realistic estimate of the potential for utilizing reused water as one component of a city’s sustainable potable water supply.
Globally, water reuse has been recognized for decades as a key component of sustainable water management in water scarce environments. However, water reuse has not been widely implemented in South Africa, largely due to negative public perceptions. For example, while water reuse was previously proposed for the eThekwini (Durban) Municipality and the city of Cape Town, the tactic was ultimately rejected in favor of seawater desalination due to public concerns. Yet treating wastewater for potable water reuse using reverse osmosis necessitates only one-third the energy requirement of ocean desalination and costs approximately 30 percent less. Figure 1 below provides a comparison of costs and energy usage between various desalination and water reuse plants in South Africa and the region.
Although water reuse is not widely utilized across South Africa, there are some local success stories. The community of Beaufort West in the Karoo region, for instance, blends approximately 20 percent reused water into its water supply from local dams. There are also several notable examples of municipalities in nearby countries successfully reusing water as a component of their potable water supply. Windhoek, Namibia’s capital, is a global leader in water reuse, for example. The city has been relying on reused water to augment its drinking water supply for 50 years, and possesses a stellar record of delivering safe, clean water even during multi-year droughts. As shown below in Figure 2, Windhoek increased its reliance on reused water from 16 percent to 29 percent during its 2015-16 drought.
Technically, treating reused water up to potable standards is straightforward. The technologies and systems required to reliably treat water—even water from domestic and industrial sources—are well established and readily available. The most significant impediment to more widespread adoption of water reuse is public perception. In an effort to change this perception, the city of Windhoek uses stringent monitoring of water quality coupled with a robust public education campaign. Similarly, Beaufort West in South Africa uses a transparent and inclusive public consultation process as part of its Environmental Impact Assessment complemented with an ongoing education campaign. Beaufort West has also adopted a very conservative design with multiple treatment barriers to ensure the safety of the drinking water.
A second important impediment to widespread adoption is the initial capital investment required to effectively reuse water to meet drinking water standards. For instance, the Beaufort West treatment plant uses a nine-step process that includes pre-treatment, rapid sand filtration, membrane ultra-filtration, reverse osmosis, and advanced oxidation. This multi-barrier treatment approach adds complexity and cost compared to traditional treatment processes. However, treatment costs are offset by the fact that the source water is essentially free compared to other bulk water sourced from dams or groundwater. Furthermore, the water produced from reused water is often of a higher quality than other potable water sources.
To help South African municipalities formulate approaches to mobilize public and financial support to adopt water reuse strategies, the USAID Water, Sanitation and Hygiene Finance (WASH-FIN) project recently partnered with the Development Bank of Southern Africa (DBSA) to host a workshop for South African municipal leaders.
USAID/WASH-FIN invited Mike Markus, general manager of the Orange County Water District, and Adan Ortega, a water and natural resources policy and strategic communications expert, both from California—a part of the United States with a similar drought profile to South Africa’s. Markus and Ortega shared their experiences working with water reuse technology and discussed public perception issues and other barriers to implementation.
Key takeaways from the workshop included:
Water reuse technology has been in use for more than 50 years, and is currently operating at scale in places like Windhoek, Namibia, and Orange County, California.
There are numerous examples of small water reuse schemes in South Africa, but these are generally implemented on an ad hoc basis or as an emergency measure during severe drought, rather than incorporated as an integral part of the water system.
There is extensive scope to expand water reuse in South Africa, especially in coastal communities.
Water reuse for non-potable uses (e.g., landscaping, industry, power) can also be expanded, which will reduce demand for potable water.
Gaining public acceptance of water reuse requires 1) early and transparent engagement; 2) education and marketing; 3) public trust in institutions responsible for water quality; 4) appropriate use; and 5) discounted pricing.
The workshop is expected to lead to the development of one or more pilot municipal water reuse projects with continued support from USAID and DBSA. Building off of successful project models, these pilots will promote the adoption of water reuse as an inexpensive, readily-available component of sustainable municipal water supply, and help South African cities ensure consistent water service to their constituents, even in the face of tightening water supplies.
Interested in learning more about water reuse? Please have a look at this blog on water reuse and the paradigm shift in Latin America, and this blog on water reuse lessons from countries in southern Africa and beyond.
By Jeremy Gorelick, senior infrastructure finance advisor for WASH-FIN, and Christopher Serjak, technical advisor for WASH-FIN’s activities in southern Africa. WASH-FIN is a five-year technical assistance project which closes financing gaps for universal access to water and sanitation.