Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.005.

Section : Water left in a container after an allowable animal has drunk from it.

Such water is considered pure. Since the animal qualifies for consumption, its saliva is also pure. Abu Bakr ibn al-Munzhir said, “The scholars are agreed that such water is permissible to drink or use for ablution.”