Unless African cities improve water management many will face severe water problems by 2035.
It's important to be wary of planting trees in places where none exist, or where there are significant water constraints.
Bangalore's forgotten water wells are being revived, to help the city overcome centuries-old supply issues.
Climate change plus population growth means the city has to act soon.
When day zero arrives in Cape Town, the routine surveillance systems that monitor disease outbreaks will be enhanced to pick up new diseases.