The solution is logical and simple. Bermuda's only source of natural water is rain and so every drop of rainwater is collected from roofs, where it drains into a tank and is then pumped towards taps when it's needed. 1.2 billion people live in areas where water is scarce and experience water shortages. Could Bermuda's harvesting system work elsewhere? Find more innovative ideas from the first series go to www.bbcworldservice.com/perfectcountry