The Playpumps are specifically designed and patented roundabouts (1) that drive conventional borehole pumps (2), while entertaining children. The revolutionary pump design converts rotational movement to reciprocating linear movement by a driving mechanism consisting of only two working parts.Link (Thanks, Thesik!)
This makes the pump highly effective, easy to operate and very economical by keeping costs and maintenance to an absolute minimum. The pump is capable of producing 1400 litres per hour at 16 rpm from a depth of 40 metres and is effective up to a depth of 100 metres. A typical hand pump installation cannot compete with this delivery rate, even with substantial effort.
Playing on a roundabout or merry-go-round has always been fun for children, so there is never a shortage of 'volunteers'. As the children spin, water is pumped from underground (3) into a 2500 litre tank (4), standing seven metres above the ground. A simple tap provides easy access for the mothers and children drawing water (5).
Update: WES sez, "A truly amazing eco-village in Colombia created dozens of valuable innovations beginning in the 1970s for folks living in dry or powerless areas, among them a sleeve pump powered by a children's see-saw."
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.