Water adsorption and desorption (H2O and D2O) were studied on vicinal Ru(0001) surfaces with nominal (101l) (l = 8, 12, and 22) orientations employing low-energy electron diffraction (LEED), thermal desorption spectroscopy, and work-function change measurements (Delta Phi). LEED measurements and theoretical calculations from clean Ru(101l) confirmed the existence of terraces with average regular spacing and steps of one atomic height. Due to the hcp structure of Ru the terrace width and the atomic arrangement of the step alternate from one terrace to the next. This is confirmed by LEED measurements and calculations showing a triple-spat splitting of the reflexes. For water adsorption, due to the presence of steps, new desorption states with higher desorption temperature (220-350 K) are observed, which are missing on the flat Ru(0001) surface. LEED experiments demonstrate that the ordered water overlayers found on Ru(0001) are absent on the stepped surfaces. The isotope effect for D2O (the so-called Al desorption state found for H2O at 212 K is missing for D2O) is also observed on the stepped surfaces indicating that this effect is due to a short-range interaction rather than a longer-range interaction in the water bilayer.