Civil Engineering June 2021 | Vol 29 No 5

Civil Engineering June 2021 19 N o matter how imaginative and optimistic we can be, it appears that there will likely be a strong link between urban development and con- sumption of fresh water for many years to come. If we want to grow our economy and lift our citizens out of poverty, we will need to use more water. Almost every personal, social, and economic activity depends on it. From health services to industry, from leisure to commerce, we seem unable to do much more with much less. And yet it seems that we are reaching some sobering limits on how much clean freshwater nature can provide us. Given the severity of droughts we have faced in recent years and the uncertainty in how our climate will change, simply relying on rainfall is no longer a smart strategy. Even if rain were assured, the social and envi- ronmental impact of building large dams far from cities makes it hard to justify such projects. And supposing we could build the dams, pumping water from so far away can be energetically unreasonable. Many of our aquifers are also reaching the limit of what they can provide due to over-abstraction and pollution. As engineers we do not often accept limits. Rather than acknowledging a limit, and changing behaviour to respect it, engineers come up with ways to overcome or work around it. They will brainstorm, innovate, and invent a ‘solution’. Most of South Africa’s cities have grown over decades and centuries by the grace of this very characteristic of engineers. We have overcome limits and found ways to hold back the sea and flooding rivers, to enable movement of people and goods across all terrain and obstacles, to give energy to millions of people, to ensure sanitary living condi- tions by removal and disposal of wastes, and to reliably provide the most essential of services: clean, fresh water. So, when faced with a terrifying limit of freshwater supply, the stereotypical engineer’s instinct is not to ask how we can slow down or cut back our demand, but rather to ask where or how we can get more water. More dams? Transfers from other catchments? Drill more boreholes? Desalinate seawater? As engineers we need to recognise that this approach is not our only option. We should rather be asking how we can respect this limit, how we can rethink our relationship with water, and how we can be its best custodians. Cautious first steps in city‑scale water reuse How South African cities can plan and prepare for largescale water reuse schemes: Cape Town’s experience. Daniel Petrie Pr Eng Professional Engineer Zutari Inside Cape Town’s proposed Faure New Water Scheme (Credit: City of Cape Town)