Rutile titanium dioxide (TiO2) (110) surfaces were examined in water using a frequency modulation atomic force microscope. On the surfaces cleaned by Ar+ sputtering and annealing in ultrahigh vacuum, step-terrace structure was observed. The inlets at the steps and the pits on the terraces indicated erosion of the surface in water. Strings extended to the  direction were occasionally observed in the topography images and assigned to the clusters of the H2O molecules. The tip experienced a repulsive force when the vertical tip position of z was less than 6 nm from the surface, and the force oscillated at z at less than 2 nm. The repulsive force originated from the disruption of the hydrogen bonding network of H2O molecules formed on the hydrophilic sputter-annealed surface. The oscillatory force arose from structural alternate order-disorder transitions of the H2O molecules at the gap between the tip and the TiO2 surfaces. On the TiO2 surface annealed in air, no strings were observed in the topography images. The tip experienced an attractive force before experiencing a repulsive force in its approach to the surface. Oscillatory behavior was not observed in the force curve. The air-annealed TiO2 and tip surfaces were both hydrophobic and attracted to each other to expel the H2O molecules from their gap. Ordering the H2O molecules at the gap between the two hydrophobic surfaces was entropically unfavorable.