It is first demonstrated that a simple Morse potential can fit very well the ab initio interaction energy for both the linear H bond of the water dimer and the bifurcated arrangement in HOH‥HOCHCHOH, using simple physical properties as the parameters in the function. This energy correlates linearly with the stretching observed in the internal OH bond of the proton donor water, leading to the formulation of an analogous Morse function that can describe the latter stretch. Although simple physical parameters can be used for the linear H bond, a good fit is achieved in the bifurcated case only after the parameters are adjusted empirically.