I think waters can vary so so much. Have known of many demonic ones and some amazingly well mannered ones. I have a 6ft male and he is the most docile snake I have seen, not even cage protective!! It makes me grin when i hear of stories of the "devil inside a water body" and then I reach in and grab mine and he is like bob marley - ccoooollll mon....lol
Just goes to show that whilst various species have common traits, every snake is different. I think there are many reasons why some are calmer than others, but they all have the ability to bite, some are just more eager than others......
If you have a water that is a great handler, as already stated, then they can be a an awesome snake. Mine is certainly one of my favorites.
Cheers