I have seen a lot of good work on water-cooled heat shields, particularly those that "sweat" water through a porous surface or in some way use the water to form a film over the outer surface before being dissipated. For very hot points on a vehicle (nose caps, leading edges) it's actually a very viable solution, requiring little additional weight in water. I have done designs based on this. Interestingly, ejecting water at the nose cap of a vehicle during launch also reduces drag losses, but that's another story.

My concepts are kind of "belt and suspenders," in that an expendable layer of ablative figures in the design to back up the water cooling in case of failure. More weight, but there it is. While an ablative is difficult to replace and maintain on a reusable vehicle, it is acceptable as one-time emergency backup.