Sukkah 50A

ואי מייתי במקודשת, איפסילו להו בלינה. חזקיה אמר: כלי שרת אין מקדשין אלא מדעת, וגזירה שמא יאמרו לדעת נתקדשו.

And if he brings the water in a consecrated jug, the water will become disqualified for use in the libation by remaining overnight, just as all consecrated items, e.g., offerings, are rendered unfit after remaining overnight. Ḥizkiya said: Temple vessels consecrate only with specific intent. Therefore, in theory, one could bring water to the Temple in a consecrated vessel, provided he has no intent to consecrate it. And the reason one may not do so is due to a rabbinic decree lest people say, upon seeing the water poured in the morning, that the water was intentionally consecrated. In that case, they might draw the mistaken conclusion that remaining overnight does not disqualify liquids for use in libations.

אמר רבי ינאי אמר רבי זירא: אפילו תימא יש שיעור למים, וכלי שרת אין מקדשין אלא מדעת, וגזירה שמא יאמרו לקידוש ידים ורגלים מלאן.

R' Yannai said that R' Zeira said: Even if you say that there is a requisite measure for the water to be poured for libation and no more than 3 log can be consecrated, and that Temple vessels consecrate only with intent, here there is a rabbinic decree lest they say the jug was filled with water for sanctifying the hands and the feet of the priest, for which there is no measure. Then, when they see the water poured in the morning, they will draw the mistaken conclusion that remaining overnight does not disqualify liquids for use in libations.

נשפכה או נתגלתה כו׳. ואמאי? ליעביר במסננת. לימא מתניתין דלא כרבי נחמיה, דתניא: מסננת יש בה משום גילוי. אמר רבי נחמיה: אימתי ⁠— בזמן שהתחתונה מגולה, אבל בזמן שהתחתונה מכוסה, אף על פי שהעליונה מגולה ⁠— אין בה משום גילוי. מפני שארס נחש דומה לספוג צף ועומד במקומו.

§ The Mishnah continues: If the water in the jug spilled or was exposed overnight, the water is disqualified. The Talmud asks: Why is the water disqualified? Let him pass it through a strainer, eliminating the poison. Let us say that the Mishnah is not in accordance with the opinion of R' Neḥemya, as it was taught in a baraita: A vessel covered with a strainer is subject to the halakha of exposure if the vessel is left unsupervised. R' Neḥemya said: When is this so? It is when the lower vessel, in which the liquid collects after passing through the strainer, is exposed. However, if the lower vessel is covered, even if the upper vessel is exposed, it is not subject to the halakha of exposure, because the poison of a snake is like a sponge in that it floats and stays in place.