(85a) which says, there is a certain nation known as חיוי which literally means snake. The Gemara explains, they are known as “snake” as they taste dust like a snake. Rashi explains: They taste the dust of the land to determine what it is suitable for, like a snake which tastes dust. We see from here, snakes taste dust and are able to distinguish between the different types.
However, we can refute this proof, as perhaps the nation does an act which is like a snake in that they taste dust, however, the snake itself cannot differentiate between different tastes.
A Question on the Approach of the Vilna Gaon
According to the approach of the Vilna Gaon, since the way a snake determines what the beverage is, is by tasting it, and through tasting it determines if it’s something it likes or not, surely all beverages should be forbidden, as perhaps a snake tasted it, and even if it subsequently decided it doesn’t like it, perhaps it emitted venom at the beginning when tasting it?
What we have to say is, Chazal knew that when a snake tastes something it doesn’t emit venom, and that snakes only emit venom when they truly like the beverage and drink from it properly.
Mashkim Megulim Applies Both by Day and Night
There is a common misconception that the laws of mashkim megulim only apply at night, however, this is incorrect and the if a beverage is left uncovered and unsupervised even for a few moments, even during the daytime, it is classified as mashkim megulim.
What Is Needed to Avoid the Issue of Mashkim Megulim?
From the Yerushalmi in Terumos it seems that to avoid the issue of mashkim megulim the beverage needs to be covered with a very strong seal, such as a cork, as only such a type of seal a snake is unable to remove. The Pri Chodosh (Yoreh Deah 116:1) takes on likes this lemaaseh [practically] and says that a seal not as strong as this is no good.
However, the poskim who are actually concerned for mashkim megulim nowadays, such as the Chazon Ish, R’ Chaim Kanievsky and R’ Elyashiv all say that if the beverage was loosely covered with a paper plate or napkin etc., it is sufficient.
If the beverage was left uncovered inside a closed refrigerator, it is permitted.
If the beverage was left on the stove in an uncovered pot which was boiling and emitting steam, it is permitted.
Unsupervised
If the beverage is uncovered, but is being supervised, it doesn’t become mashkim megulim. The question is, what exactly is considered unsupervised?
“Unsupervised” means that the beverage was left completely alone for a few moments. If, however, there was a person who was fully awake — even a baby — in the room, the prohibition of mashkim megulim does not apply. This holds true even if the person in the room was not watching the beverage at all, and even if his eyes were closed the entire time and even if the room was dark.
A closed-circuit camera is not considered supervision concerning mashkim megulim.
Some poskim hold that yotzei venichnas supervision —i.e., a beverage left uncovered and unsupervised in a room where there is constant traffic — is considered sufficient supervision. Others, however, hold that yotzei venichnas is not valid for mashkim megulim.
For Those Who Are Stringent, Does Nullification in 60 Help?
The Birkay Yosef, Pri Chodosh (116:3), and Yad Ephraim (beginning of Yoreh Deah 116) all say, that for those who are concerned for mashkim megulim, nullifying it in 60 doesn’t help.
The sefer Yisa Yosef (Yoreh Deah, 2:15) writes that experts told R’ Elyashiv that venom of a snake isn’t nullified, even in 60.
If One Is Particular About Mashkim Megulim and It Was Left for 24 Hours in a Utensil, Does The Utensil Need to Be Kashered?
R’ Avigdor Nevensal was asked: “For those that are concerned about giluy, if the beverage was left in a utensil for more 24hours, does the utensil need to be koshered?”
R’ Nevensal answered: כמדומני שלא – “I think not” (cited in Ohel Yaakov, Macholei Akum)
The Shevet HaKehosi (3:223) writes: In a place where there are snakes commonly found one should kasher the utensil, and it doesn’t help even if one leaves the utensil for a day. If, however, snakes are not common, then the utensil is ok, even without hagolah, even within 24 hours.
Are Beverages Subject to the Laws of Mashkim Megulim on Seder Night?
Seder night is a night which is guarded from mazikim [demons], does this help for giluy? When R’ Chaim Kanievsky zt”l was asked this, he said: ממזיקין ולא מנחשים – “The night is guarded from demons not snakes.” (Heard from R’ Shragi Kallus shlita)
Mashkim Megulim Shouldn’t Be Spilt Out into the Public Domain, or Used for Washing Floors, or for Washing Oneself
The Gemara in Avodah Zorah (30b) quotes a beraisa which teaches that mashkim megulim shouldn’t be poured out into the public domain as we are worried that people will walk on it whilst walking bare foot, it shouldn’t be used to wash floors, and one shouldn’t even wash himself with it. The Tur brings this down l’halachah.
Swimming / Going to Mikveh in Mashkim Megulim
For those who are concerned about mashkim megulim, is it ok to go swimming or to mikveh in such water?
R’ Mordechai Karp in his Hilchos Shabbos B’Shabbos (pg. 402) brings from the Pri Toar that we don’t find that people die from snakes today, and although there is still room to be stringent when it comes to drinking from mashkim megulim, there is room to be lenient to bathe and wash in such water. R’ Karp brings that he heard from R’ Elyashiv as well, that one can rely on the Pri Toar for this, and be lenient nowadays to wash in water that was left uncovered.
Can One Use Mashkim Megulim to Wash His Car?
The Sefer HaMechonit V’Hilchoseho (והלכותיה המכונית ) discusses this and he writes: Since the water will end up in the public domain, we need to be concerned that one may walk past with sandals and no socks, and some of the water will get in-between his toes and cause him harm. Especially, if such a person has an open cut.
Using Mashkim Megulim for Kiddush and other Ritual Purposes
Even those who are generally lenient with mashkim megulim are careful not to use such wine for Kiddush or for other ritual purposes which require wine, such as Havdolah and Birchas Hamazon, since it is considered demeaning to use mashkim megulim for mitzvos. Lechatchilah [ideally], therefore, wine which was left uncovered and unsupervised for even a brief period — as little as twenty minutes — should not be used for mitzvos. If, however, no other wine is available, one may use such wine as long as its taste and smell were not compromised in any way. If the wine was left uncovered for five or six hours, and surely if it was left uncovered overnight, we are concerned that its taste or smell was affected and it may not be used for Kiddush etc., even bedieved.
