How does the halacha view moisture, or condensation often found on the outside of vessels? Is it considered, halachically, to be water? Some prove from the mishna (Machshirin 2:2) that steam, or vapor is only considered to be "water" if it comes from a clear source, such as the steam from a mikve. Condensation, however, would not halachically be considered water.
If this is true, are there any practical, halachik ramifications? Let’s look at three different cases
The Shulhan Arukh (Orah Haim 158:4) discusses a "davar shetibulu bemashkeh" – a fruit which has been dipped in water. The Talmud teaches that one is required to wash one’s hands, with a cup, before eating a wet fruit which has been immersed in one of the "seven liquids" (wine, hone, oil, milk, dew, blood and water). That is why we wash our hands before "karpas" on Pesah. It would seem, therefore, that one is not required to wash one’s hands before eating fruits which are moist from condensation, as condensation is not considered to be one of these seven liquids.
However, regarding Mayim Aharonim (i.e. the requirement to wash ones hands after eating bread, before reciting the birkat hamazon), the Shulhan Arukh (181:9) writes that one may clean one’s hands with any liquid, not specifically water. It would seem that in this case, since one does not need to use water, one would be allowed to moisten one’s hands even with the condensation on the side of a glass and then say birkat hamazon.
Finally, regarding the laws of Shabbat, this water would be considered to be a nolad, i.e. something which did not exist before Shabbat, and which was created on Shabbat. Nolad is considered to be mukse and cannot be handled (tiltul) on Shabbat. Therefore, one would not be allowed to use this condensed liquid for mayim aharonim on Shabbat, as it is considered to be mukse.
Interestingly, the Hazon Ish questioned whether one may wipe condensation from a jar or pot before bringing it to the table? He insists that cleaning or wiping is not considered to be a violation of the laws of mukse, i.e. "tiltul," and therefore there is no prohibition of cleaning dirt, or condensation from a vessel. However, as mentioned above, it would be prohibited to use the moisture for mayim aharonim, on Shabbat, as that would be a form of "tiltul."
