Pure water comes from the Hydra spawn in the jungles east of Port Hope, in the mountains. This water is said to be very pure and clean; it may have special properties to grow or heal. It should be collected in a special Waterskin by using it on a trickle.

Click Here to Show/Hide Spoiler Information
Spoiler warning: Quest and/or game spoiling details follow. (Settings: hidden content)
This special water must be collected in Ceiron's Waterskin, as Ceiron requested, in the Druid Outfits Quest.

It can be filled here.Pure water location

Spoiler ends here.