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.

This special water must be collected in Ceiron's Waterskin, as Ceiron requested, in the Druid Outfits Quest. It can be filled here.