If you want to be physically accurate, you need to set metallness to “0”, as water isnt a metal.
Additionally you need to set the specular value to something else than “0” because having a specular of 0 makes your water non-reflective. See the documentation for more info. Leave Specular at 0.5 (the default) or set it to something that pleases your eye (The docs recommend 0.255 for water).