Q. I know that according to some, there is an issue with drinking liquids that were left uncovered for a period of time. I’m wondering if the same issue applies to water that will be used for washing netilat Yadayim in the morning (not for drinking). Also, there is a halacha not to leave food under a bed, but would this apply to the water for washing in the morning? In summary:
1. Does the water we prepare by our bed for washing in the morning need to be covered all night?
2. To avoid kids spilling the water, is it okay to keep in under my bed overnight?
Thanks so much

A. Shulchan Aruch (O. H. 4: 7) rules that one should be careful to observe and keep all the restrictions that apply to the water used in netilas yodaim for eating bread, equally to the water used when washing hands when one wakes up (neigel vaasser). Shaarei Teshuva (ibid) writes that although some are stringent in drinking water left uncovered in our days, and are machmir even for netilas yodaim, the common minhag is to be lenient, since the presence of poisonous snakes is unusual. However, Orchois Rabbenu (1: 206) quotes that the Chazon Yish and the Steipler zt”l would refrain from using uncovered water for neigel vaaser.
In regards to water left under the bed where one slept, in question 1168 we wrote in regards to avoiding using water used in a pillow or water mattress, because the water would acquire a ruach ra and one would be continuously in touch with it. Also if one can you use that water for neigl vaser. We wrote;
“The Talmud (Pesachim 112a) teaches that food and beverages left underneath a bed, even if covered in iron a ruach ra or bad spirit will rest on them. Shulchan Aruch (Y.D. 116: 5) rules accordingly that they should not be placed there. After the fact, Poskim disagree whether one can consume them them or not.
Horav Shlomo Miller’’s Shlit’a opinion is that this applies to water used for drinking and not one dedicated for support and comfort purposes. Even if a ruach ra would rest on them, there is no issue with laying on them or next to them.
Shevet Halevi (8: 22: 2) debates whether such water could be used for netilas yodaim after sleeping on them, to remove the ruach ra from the hands. He permits when no other water is available. Piskei Teshuvos (4: 12) is equally lenient after the fact
Horav Shlomo Miller’s Shlit’a opinion is that the water on a water mattress or pillow should not be used for netilas yodaim since it was used for doing work (Na’ase bohem melacha), besides it is likely not fit for drinking. However, water left under the bed could be used for this ruach ra netilas yodaim. See also question 682 in regards to oil left uncovered for Chanuka lights use.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a