Good picture. I agree that the water line should be centered since it enhances the symmetry of the building and its reflection. However, this doesn't leave you with much to follow the rule of thirds. The trees do, but those aren't a major element of the picture. I would suggest cropping them out and leave the potted plants and their reflections at the four "rule of thirds intersection" points.
Sheesh. This is a lovely, serene shot but it is SO not rule-of-thirds. It's split down the middle horizontally, symmetrically mirrored top-to-bottom. The trees on the left are entirely to the left of the first 1/3 vertica lline... Nice shot though :-)