It was supposed to be a simple technology change to solve the problem of pumping water for women and children. Replace hand pumps with merry-go-rounds and when children play the water is pumped (like a windmill on its side) into a storage tank. Apparently $60 million was raised, including $10 million from the US government and $5 million from the founder of AOL.

Instead, in just three years, it has quietly become a study in product failure.

Costello visited more PlayPump sites, the next one in a more remote part of Mozambique with fewer children around. Women tell her that spinning the merry-go-rounds is often hard work without help, and hard especially for the older women. They tell her the old hand pumps were much easier, and that no-one consulted them about the change. The PlayPump just arrived.