Take a read through my guide, incomplete but it covers some stuff like this. Linked in my sig if you want.
Now, it's time to talk briefly about quality. There are three types, Essence, Substance and Vitality. Each quality type influences an item in a different way. For food Vitality increases the FEP's gained, Substance decreases the Hunger penalty and Essence decreases the satiation penalty. How these attributes influence an item will depend what type an item is, but for now understanding how food works is sufficient.
That's the relevant explanation that I've written so far. Vit seems to cover "how good this thing does its job", Ess and Sub both seem to reduce penalties associated with the item. In the case of water, Ess reduces energy penalty, sub does nothing, Vit increases stam regen.
So I know for sure that nettle V will increase the bonus. I've not the foggiest what E/S do but possibly one reduces the agility penalty. My bet would be Ess since it seems to be used first for water at least.
Edit: curios break any rules I set out btw, all 3 qualities increase the LP gained and have no other effects that I've seen.
Edit2: just because water S quality seems useless, doesn't mean it is. Because you use water to make foods, and food Sub is a nice stat to have, it ends up getting use later even if there's no utility in drinking sub water.