Water is everywhere, even in the air. Consequently, many surfaces (metallic, oxide, and semiconducting) are covered in thin layers of water. It turns out that the first contact layer is actually not pure water, but a mixture of water and hydroxyl (OH-) ions. Furthermore, on a metal surface the separation of the oxygen atoms is largely determined by the lattice constant of substrate [presumably because the oxygen atom lone pairs have a relatively strong interaction with the metal atoms].
The above is based on a nice PRL Quantum Nature of the Proton in Water-Hydroxyl Overlayers on Metal Surfaces by Xin-Zheng Li, Matthew I. J. Probert, Ali Alavi, and Angelos Michaelides.