No one can be effectively excluded from consuming it, basically. There's a lot more to say about it, though you can read about it here.
rgr
Then yes is my answer.
To clarify, nobody can deny another individual access to water. On the flip side, nobody (including a govt) should be required to make clean water available for whomever wants it whenever they want it.
The issue is availability in regards of private ownership of a reservoir, dissemination, etc,. People do get denied access to clean water, and I'd make a strong case for the responsibility of ownership to deliver clean water, whether public or private.