Is treated sewage water – which has no color or smell, and whose spray sometimes affects people – considered pure or impure?

If Najis (ritually impure) water is treated and its traces of impurity (taste, color, and smell) are removed, then it becomes Tahir (ritually pure). The ruling of impurity is lifted from it when its cause is removed. Therefore, there is no harm in any splashes of this water that may reach you, as it is pure.