  We report the first observation of intermolecular Coulombic decay (ICD) in
liquid water following inner-valence ionization. By combining a monochromatized
table-top high-harmonic source with a liquid micro-jet, we recorded
electron-electron coincidence spectra at two photon energies that identify the
ICD electrons, together with the photoelectrons originating from the 2a$_1$
inner-valence band of liquid water. The ICD-electron spectra agree well with
those measured for large water clusters, $\langle N\rangle \approx 241$, but
are broader compared to those obtained from smaller water clusters, $\langle
N\rangle \approx 12$. Our results confirm the importance of ICD as a source of
low-energy electrons in bulk liquid water and provide quantitative results for
modeling the velocity distribution of the slow electrons that are thought to
dominate radiation damage in aqueous environments.
