Covering the Negel Vasser water: [1]
Is the Negel Vasser water which is set up at night prior to going to sleep to be covered? Why do some do so?
Many Poskim[2] rule that there is no need to be stringent against washing hands with water that was left uncovered overnight. This applies even in an area where snakes are commonly found.[3] However, there are Poskim[4] who are stringent and rule that one is to avoid washing with waters left uncovered. [A simple way of achieving this is by turning the basin over and placing it on top of the Neigal Vaaser cup.] Practically, the custom is to be completely lenient even regarding drinking waters that were left uncovered, and certainly regarding using it for washing[5], and so is the apparent Chabad custom.[6] There is likewise no problem to wash hands for bread using revealed waters even in areas that snakes are common.[7]
Children: There is no extra stringency relevant to covering the Neigal Vaaser water of children at night, other than simply to prevent it from spilling, as commonly occurs with kids. Special Neigal Vaaser cups with covers for kids are manufactured for this purpose.
[1] See Hakashrus p. 432; Piskeiy Teshuvos 4:12
[2] Shalmei Tzibur brought in Shaareiy Teshuvah 4:7; Pischeiy Teshuvah Yoreh Deah 116:1; Peri Toar Yoreh Deah 116:2; Birkeiy Yosef 116:4; So is also implied from M”B 160:23; Admur 272:1 rules we are no longer careful regarding revealed waters as snakes are no longer commonly found.
[3] Shalmei Tzibur ibid; See however Poskim in next footnote that one is to be stringent in those areas that snakes are common.
The reason: As the prohibition relating to waters left uncovered in areas that snakes are commonly found, is only in regards to drinking the liquid and not to using it for washing. [Shaareiy Teshuvah ibid; M”B 160:23]
[4] Rav Sheptal brought in Shaareiy Teshuva ibid; Seder Hayom: “Every G-d fearing Jew needs to prepare for himself prior to going to sleep two vessels, one that contains water and one that is empty, into which he will pour the water upon awakening. One is to place the water filled vessel into the empty vessel, covered and clean.”; Chesed Lealafim 4:10; Kaf Hachaim Falagi 8:11; Kaf Hachaim 116:8 and Artzos Hachaim 4:1 that one is to be stringent in those areas that snakes are commonly found. [brought in Hakashrus 18:19]
[5] Conclusion of Shaareiy Teshuvah ibid
[6] See Migdal Oz story 114 from which it is evident that it was not widely practiced amongst Chabad Chassidim to cover the Neigal Vaaser water at night prior to going to sleep. This is understood from the fact the apprentice of the Tzemach Tzedek could not understand why he covered the water, as well as from the fact that one Chassid complained to the Rebbe Rashab about the stringencies of another Chassid who followed this stringency of covering the water. Nevertheless, as is evident from the story, this was the custom of the Tzemach Tzedek, and of certain scrupulous Chassidim. However, from the response of the Tzemach Tzedek it can be understood that this custom is not meant as a directive for the public. Vetzaruch Iyun
[7] Levush 160:5; Aruch Hashulchan 160:1; M”B 160:23 [It is implied from there that he rules even regarding washing hands upon awakening there is no need to be stringent]; See however Kaf Hachaim 116:8 that one is to be stringent in those areas that snakes are common.