Take the Corrupt Moon Well Water to Islen Waterseer in the Barrens.
Take the corrupt water to the Barrens, [player]. South of Ratchet, hidden along the shore, is an old friend of mine, a shaman named Islen Waterseer. She is a powerful shaman who will help us. Her relationship with the spirits of water has always been strong. Our task being a noble one should be enough to persuade her and the spirits of water to aid us in this task.
You should find her at a small camp right along the water's edge. And, [player], ignore the pirates... they are but a nuisance and no threat to you.