All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Yes, it is permissible to use drainage water in watering plantations and trees whether this is before refining it or after refining it, as the impurity will be transformed to another substance at the end, and this is the view of the majority of the scholars.
Allaah Knows best.