It's actually going on in Hawaii, where harvested and desalinated deep seawater is an industry worth $16.8 million a year. Japan is the main market, where end users pay around $6 a litre.

Mauritius is aiming to take a leaf out of Hawaii's book using plastic pipes to extract seawater that has been carbon dated as at least 500 years old.

A technical feasibility study is being undertaken by Makai Ocean Engineering, which helped to develop the Hawaiian industry, AllAfrica reported.