Rural Aussies have already solved the water tank problem. Pollie tanks as the Aussies say, or polyethylene tanks. There are more brands of water tanks than you can poke a stick at- Nylex (ARI) Plastank and Nylex Pura Tank, Bushman, Clarks, Aquasource, Rainmaster, Tankmasta, Team Poly, Duraplas, Rainhaven, Poly Water Tanks and a host of others around the country. The proliferation of brands is a product of the cost of trucking the tanks long distances.
Personally I don’t see this as a solution to Third World water shortages, but rather a solution for 7 star resort islands to appeal to their super rich and eco-trendy clientele. hence they are testing in Curacao.
Bladder tanks are much cheaper to transport but not as durable.