Ballonpumpe

Pull the rope with balloons downwards and watch how water is pumped into an elevated tank. During water pumping with balloons water is captured in a narrow tube between two knots. The balloons must have the same diameter as the tube to prevent water flowing down through a gap by gravitation. In this case the energy needed to overcome gravitation is supplied by human muscles. The task of transporting water over a long distance or pumping it up from a great depth had to be addressed by the earliest civilisations. But we can run into small mechanical pumps even in our households. A piston pump can be found in a liquid soap dispenser.