Cape Town faces the unenviable situation of being the first major city in the modern era to run out of drinking water.
São Paulo Brazil’s financial capital and one of the 10 most populated cities in the world went through a similar ordeal to Cape Town in 2015, when the main reservoir fell below 4% capacity.
China is home to almost 20% of the world’s population but has only 7% of the world’s fresh water.
Official figures from 2015 showed that 40% of Beijing’s surface water was polluted to the point of not being useful even for agriculture or industrial use.
The UN estimates critical shortages in the country by 2025.
Jakarta Like many coastal cities, the Indonesian capital faces the threat of rising sea levels.
As a consequence, about 40% of Jakarta now lies below sea level, according to World Bank estimates.
Moscow One-quarter of the world’s fresh water reserves are in Russia, but the country is plagued by pollution problems caused by the industrial legacy of the Soviet era.
According to the Greater London Authority, the city is pushing close to capacity and is likely to have supply problems by 2025 and "serious shortages" by 2040.
Rainfall, however, is concentrated during just four months of the year.