However, it is very easy to say veganism is unhealthy and has a greater environmental impact. Yet no one is in the same breath saying the same thing about non-vegans and those who live off processed foods and are wildly unhealthy. The fact is that most vegans have better weight management and the few studies suggest that being vegan seems to correlate with better health…although the evidence for this is still very limited. And of course flying in almond milk or avocados has an environmental impact, but the impact of animal farming is significant - the amount of water required for beef, and the amount of feed that cows require is shocking compared to the amount of food that is actually produced.
So this water thing:
It would be an issue in a place like California, where they are in a drought, and draining their aquifer for agriculture. And places like California send out large amounts of water in the form of all kinds of agricultural products. Similarly Israel, IIRC. It's a problem because it is affecting the local ecosystem.
But if you live in a place with lots of water, and a cow drinks it, that is not necessarily a problem. The water doesn't disappear from the world, it's just being held in a body, the same as with plants that suck up water. And the ecosystem isn't being impacted significantly by the cow drinking that water.
It's when you have certain regions that are exporting so much food to other places, especially in fragile ecosystems, or things like big feed lots where there is so much water needed and also so much organic waste, that you run into trouble. But even growing things like oranges for export in places like that can be very problematic. It's asking more of the land than it can really give.
People disparage the idea of food miles, but it's not as straightforward as many seem to think. It's also about the reality that you have some regions that end up being seriously over-farmed, or places in far off countries where you really can't see the farming or labour practices, or affect the regulations.