If "withholding" means actively blocking someone from acessing water they already have a right to, you'd be correct. But that's not what's in your link. Passive possession, "I have water, I'm not giving it to you," is not initiation of force. It's simply not being someone else's servant.

And it's unjust to assume humanity wouldn't help unless forced to.

By calling upon sacrifices, the first target would be engineers, plumbers, and utility workers. Forcing the people who actually produce and deliver clean water isn't justice.

You're completely discounting the most perfidious type of violence: economic violence.

Punishing and preventing it is the core purpose of the state.