The water tile's expanded bounds would cause materials to leak outside of the water body.
Use the unexpanded bounds to reduce leaking as generally this feature will be for an inland body of water where hopefully there is attenuation between it and the ocean to handle the ocean's displacement. The inland water body will unlikely have large displacement but can be mitigated with a decent buffer zone.
The water tile's expanded bounds would cause materials to leak outside of the water body.
Use the unexpanded bounds to reduce leaking as generally this feature will be for an inland body of water where hopefully there is attenuation between it and the ocean to handle the ocean's displacement. The inland water body will unlikely have large displacement but can be mitigated with a decent buffer zone.