Mishnah Parah 11:1: A vial [of water sanctified for the chatat ritual] which one left uncovered, and [then] returned to find it covered, is invalid [for the ritual]. If one left it covered and returned to find it uncovered, if a weasel could have drunk from it--or a snake, according to Rabban Gamliel--or if dew descended into it at night, it is invalid. The chatat [ashes or water, contained inside a vessel] are not protected [from impurity] by a tight seal [if they were in a tightly sealed vessel incapable of becoming impure from the outside]; but waters which were not sanctified are saved [from impurity] by a tight seal.

צְלוֹחִית שֶׁהִנִּיחָהּ מְגֻלָּה, וּבָא וּמְצָאָהּ מְכֻסָּה, פְּסוּלָה. הִנִּיחָהּ מְכֻסָּה וּבָא וּמְצָאָהּ מְגֻלָּה, אִם יְכוֹלָה הַחֻלְדָּה לִשְׁתּוֹת הֵימֶנָּה, אוֹ נָחָשׁ לְדִבְרֵי רַבָּן גַּמְלִיאֵל, אוֹ שֶׁיָּרַד בָּהּ טַל בַּלַּיְלָה, פְּסוּלָה. הַחַטָּאת אֵינָהּ נִצּוֹלָה בְּצָמִיד פָּתִיל. וּמַיִם שֶׁאֵינָן מְקֻדָּשִׁין נִצּוֹלִין בְּצָמִיד פָּתִיל:

Mishnah Parah 11:2: Any doubtful case [regarding something's purity status] which would be [deemed] pure for trumah [a portion of produce which needs to be given to a priest and must be kept pure] is pure for chatat. Any [doubtful case] which is 'hanging' for trumah [i.e. not definitively deemed pure or impure, but rather is neither eaten not burned] is spilled out for chatat. [Impure trumah may not be eaten and needs to be burnt, but it is forbidden to burn pure trumah. A doubtful case of trumah is considered 'hanging' if we declare it doubtfully impure such that it may not be eaten but is still not allowed to be burnt. Invalid chatat waters, however, cannot be used for the ritual sprinkling, and thus retain no sanctity; therefore they may be discarded or destroyed.] If one [whom the chatat waters that should have been spilled out were sprinkled on him when he was impure, in order to purify him through the chatat ritual] handled pure [trumah], they are 'hanging' [and can be neither eaten nor burned. The [wooden] lattices are pure for sanctified property, for trumah, and for chatat. Rabbi Eliezer says: The shaky [lattices] are impure for chatat.

כָּל הַסְּפֵק טָהוֹר לִתְרוּמָה, טָהוֹר לְחַטָּאת. כָּל הַתָּלוּי לִתְרוּמָה, נִשְׁפָּךְ לְחַטָּאת. אִם עָשׂוּ עַל גַּבָּיו טָהֳרוֹת, תְּלוּיוֹת. הָרְפָפוֹת, טְהוֹרוֹת לְקֹדֶשׁ וְלִתְרוּמָה וּלְחַטָּאת. רַבִּי אֱלִיעֶזֶר אוֹמֵר, הָרְעָדוֹת, טְמֵאוֹת לְחַטָּאת: