Water is omnipresent and essential. Yet at the same time it is a rather unreactive molecule. The direct addition of water to C[double bond, length as m-dash]C double bonds is therefore a challenge not answered convincingly. In this perspective we critically evaluate the selectivity and the applicability of the different catalytic approaches for water addition reactions: homogeneous, heterogeneous and bio-catalytic. Here we would like to discuss how to speed up water addition and even make it selective.