  A wetting transition occurs when the contact angle of a liquid drop on a
surface changes from a nonzero value to zero. Such a transition has never been
observed for water on any solid surface. This paper discusses the value of the
temperature T_w at which the transition should occur for water on graphite. A
simple model, previously used for nonpolar fluids, predicts the value of $T_w$
as a function of the well-depth D of the adsorption potential. While $D$ is not
well known for the case of water/graphite, the model implies that T_w is likely
to fall in the range 350 to 500 K. Experimental search for this transition is
warranted. Water wetting transition temperatures on other surfaces are also
discussed.
