1) Water from which an animal has drunk, does not become unfit for washing one’s hands. If it was a dog or pig who drank, there are those who are stringent because it is repulsive, and in a time of extreme necessity one may be lenient. (Shulchan Aruch and Mishne Berura 160)
2) If a small amount of unfit water was mixed with a lot of suitable water the unfit water is Botel Berov (the majority render the minority insignificant), and all the water may be used for washing one’s hands, unless the unfit water has changed the color of all the water, in which case it is all rendered unfit. (Mishne Berura ibid)
