Mishnah Parah 6:2: If the sanctified [ashes] were floating on the water, Rabbi Meir and Rabbi Shimon say: he may take [from the ashes] and sanctify [with them]; and the Sages say: anything which has touched the water, we do not sanctify with it. If the water was emptied and sanctified [ashes] were found at the bottom, Rabbi Meir and Rabbi Shimon say: he may dry and sanctify; and the Sages say: anything which has touched the water, we do not sanctify with it.

הָיָה קִדּוּשׁ צָף עַל פְּנֵי הַמַּיִם, רַבִּי מֵאִיר וְרַבִּי שִׁמְעוֹן אוֹמְרִים, נוֹטֵל וּמְקַדֵּשׁ. וַחֲכָמִים אוֹמְרִים, כֹּל שֶׁנָּגַע בַּמַּיִם, אֵין מְקַדְּשִׁין בּוֹ. זָלַף אֶת הַמַּיִם וְנִמְצָא קִדּוּשׁ מִלְּמַטָּן, רַבִּי מֵאִיר וְרַבִּי שִׁמְעוֹן אוֹמְרִים, מְנַגֵּב וּמְקַדֵּשׁ. וַחֲכָמִים אוֹמְרִים, כֹּל שֶׁנָּגַע בַּמַּיִם, אֵין מְקַדְּשִׁין בּוֹ:

Mishnah Parah 6:3: One who sanctifies in a trough, and a tefi [a vessel with a very narrow opening] is inside it, even if the opening [of the tefi] is a [very small] width, the water inside it is sanctified. If there was a sponge [in the trough when the ashes were added], the water inside it is invalid [since the water is not contained in a vessel]. What should he do? He empties [the vessel] until he reaches the sponge [and the collected water is valid]. [But] if he touches the sponge, even if the water is floating above it in any amount, it [the water] is invalid [since invalid water left the sponge and mixed with the valid water].

הַמְקַדֵּשׁ בַּשֹּׁקֶת וְהַטְּפִי בְתוֹכָהּ, אַף עַל פִּי שֶׁפִּיו צַר כָּל שֶׁהוּא, הַמַּיִם שֶׁבְּתוֹכוֹ מְקֻדָּשִׁין. אִם הָיָה סְפוֹג, הַמַּיִם שֶׁבְּתוֹכוֹ פְסוּלִים. כֵּיצַד יַעֲשֶׂה, יְזַלֵּף עַד שֶׁהוּא מַגִּיעַ לַסְּפוֹג. נָגַע בַּסְּפוֹג, אַף עַל פִּי שֶׁהַמַּיִם צָפִין עַל גַּבָּיו כָּל שֶׁהֵן, פְּסוּלִין: