Saving someone that is about to drown, if directly faced with the situation, is clearly a moral (and probably legal) duty.

But I world argue, that supporting a solution to actively prevent someone from putting themselves in a situation where they can drown, is not a duty.

I.e.: I have the duty to help my neighbor if I see that she fell off the stairs and needs medical attention. But I don't have the duty to go check on her door every hour to see if everything is fine.

EDIT: Disagreeing with someone's comment because it goes against your political ideology, is not supposed to be a reason to down-vote a comment in HN.