In Durban, South Africa's third largest city, an amount of wastewater equivalent to 13 Olympic-sized swimming pools has been treated and reused for industrial use by a paper mill and a local refinery every day since 2001.

A public-private partnership (PPP) between the city and a private environmental services company made this achievement possible. And it is a good example of how wastewater reuse is helping some cities address critical water shortages.

Wastewater reuse - recycling and reusing water from our sewerage systems - may prompt what is quite simply known as the "yuck" factor.

People are naturally squeamish about the idea of reusing water that comes from our toilets, even though it's actually quite common. Wastewater reuse has been around for thousands of years.

In London, a significant portion of the drinking water is indirectly recycled through the River Thames, the main water source for the British capital. This is also being done in Windhoek, Namibia, where a direct potable reuse scheme has been operating since 1965.

A version of this article appears in the print on September 2 2021, of The Himalayan Times.