Water from which animals drank, for netilas yadayim

[A] (halacha 13)

Question: What is the law regarding water that animals have drunk from, with respect to washing the hands?

Answer: A vessel that contains water, and animals such as chickens or cats or other animals drank from this water — the water is valid for washing the hands, since no work was performed with the water that remained in the vessel, and therefore it is valid. However, if it is a matter of a dog or a pig or another repulsive thing that causes people to refrain from drinking the water that remains in the vessel, there are those who invalidate the water for washing, since it is defined as mei shofchin, and it is good to be concerned for this view (Seder Netilas Yadayim L'Seudah, paragraph 11). [Sharpening the ruling: the Alter Rebbe writes in the Shulchan Aruch (Siman 160, paragraph 8) and one should be concerned for their words, but in Seder Netilas Yadayim L'Seudah, which is the final ruling, the wording is and it is good to be concerned for their words — what is the difference between the two formulations? The Alter Rebbe explained (in Shulchan Aruch OC Siman 246, in the Kuntres Acharon, beginning of note 3) that when it is written that there is reason to be stringent — that is a complete obligation; however, when it is written that it is good to be stringent — that is not a complete obligation, but rather in the category of a hiddur. And if so, in practice it emerges that the Alter Rebbe in his final conclusion is more lenient].

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