Anne, to me, water really should be level. Bodies of water in images are typically associated with calm and relaxation. Certainly water and a sunset is meant to invoke that. Angles create tension in an image, and add to its dynamism.
So, if you are purposely presenting a dynamic scene with a tilt, make it so! But that tilt should look purposeful.
The tilt in your image is accidental. It happens. It can be fixed. It can be the difference in a seemingly well crafted image, or it can just look sloppy.
It's a visual language, and tilt is just another tool of expression. There is a time and place for it.
We all have images that have a little bit of a tilted horizon, and shooting a little bit wider than needed gives you room to fix it, and not cut off important things when you do.