That water claim was based on a flawed accounting that's been repeated over and over so much without source. The debunking was posted right here on HN a few years back, don't have time to find it for now, maybe later.

Other than that, what you describe only applies to industrial farming, not grazing cattle. Cows graze pasture, they shit and piss in pasture, it's almost a closed cycle except for the added salt the herder usualy gives them.