These merry-go-rounds use kid power to pump water in developing countries, so far 700 PlayPumps have been installed in South Africa – “While children have fun spinning on the PlayPump (1), clean water is pumped (2) from underground (3) into a 2,500-liter tank (4), standing seven meters above the ground. A simple tap (5) makes it easy for women and children to draw water. Excess water is diverted from the storage tank back down into the borehole (6). The water storage tank (7) provides a rare opportunity to advertise in rural communities. All four sides of the tank are leased as billboards, with two sides for consumer advertising and the other two sides for health and educational messages. The revenue generated by this unique model pays for pump maintenance. The design of the PlayPump makes it highly effective, easy to operate and very economical, keeping costs and maintenance to an absolute minimum. Capable of producing up to 1,400 liters of water per hour at 16 rpm from a depth of 40 meters, it is effective up to a depth of 100 meters. “ [via] – Link. & how it works.