The surface tension of a liquid is a measure of the cohesive forces that hold the molecules together. It is responsible for a water drop assuming a spherical shape and for the effects of surfactants to produce bubbles and foams. The value of the surface tension of water at room temperature is known accurately to four significant figures and is recommended as a standard for the calibration of other devices. New research in which Ines Hauner and Daniel Bonn (Institute of Physics) are involved now shows that this value is not as universal as previously believed.