Supplement scarce water by condensing water from air that has high relative humidity.
Pump cold seawater through condensation coils which allow condensation from humid air, and collection of water. The air around Cape Town is a good candidate having high relative humidity 70% - 80%(https://weather-and-climate.com/average-monthly-Humidity-perc,Cape_Town,South-Africa). The seawater is cold (https://seatemperature.info/cape-point-water-temperature.html) and gets colder at deeper levels - about 10 deg. C per 500 meters (http://www.destinydeepseawater.com/ocean_temp_info.html). Thus water at 5 degrees or less could be pumped up. The condensation units could be floating at sea, or stationary at the coast.
The pump could be wind-driven. “the average speed at Cape Point was 6,9 metres per second and 42%of its wind blew at eight or more metres per second.” https://mg.co.za/article/2003-07-03-which-is-sas-windiest-city
Desired hackathon goal:
In terms of ensuring that innovations do not create more problems than they solve (progress traps), the exercise would be to evaluate firstly what the potential adverse effects of the device/project would be, and if the cons do not outweigh the pros, then proceed with development.
Needed: ethical and technical evaluation of the pros and cons.
If it’s a go, technical expertise for researching the effective size of the materials, and required scale of project deployment.