So!
As it currently stands, the only methods of collecting Water are by purchasing it from an NPC or picking it up from a fallen foe. For the more survival-oriented PCs (that would never drink water from an enemy, gross), I propose a new craftable, through herbalism perhaps, that allows you to collect water from a drinkable source, filter it, and store it in a few bottles.
Survivalist's Filter
DC: 5
Crafting Points: 8
Requires:
1x Glass Bottle
2x Small Cloth
Charges: 1
Weighs 0.1
One-time use on a [Drink Water] source to create 5 Water items.
The recipe needs to be cheap and easy enough to make it a viable alternative, but not a method for infinite water acquisition for free.