Commentary for Tahorot 4:7
אֵלּוּ סְפֵקוֹת שֶׁטִּהֲרוּ חֲכָמִים. סְפֵק מַיִם שְׁאוּבִים לַמִּקְוֶה. סְפֵק טֻמְאָה צָפָה עַל פְּנֵי הַמָּיִם. סְפֵק מַשְׁקִין, לִטָּמֵא, טָמֵא, וּלְטַמֵּא, טָהוֹר. סְפֵק יָדַיִם, לִטָּמֵא וּלְטַמֵּא וְלִטַּהֵר, טָהוֹר. סְפֵק רְשׁוּת הָרַבִּים. סְפֵק דִּבְרֵי סוֹפְרִים. סְפֵק הַחֻלִּין. סְפֵק שְׁרָצִים. סְפֵק נְגָעִים. סְפֵק נְזִירוּת. סְפֵק בְּכוֹרוֹת. וּסְפֵק קָרְבָּנוֹת:
The following uncertainties [regarding impurity status] were declared pure by the Sages: the uncertainty of drawn waters for a <i>mikvah</i> [a pool for ritual immersion which must contain natural, undrawn water; the uncertainty is a case in which it is uncertain whether a <i>mikvah</i> contains enough drawn water to invalidate it from being able to purify those that immerse it in]; the uncertainty of an impurity floating on the water's surface; the uncertainty of liquids regarding whether they themselves have become impure--such [liquids] are impure, and [the uncertainty] regarding whether they rendered [something else] impure--such [items] are pure; the uncertainty of hands regarding whether they themselves have become impure, or have rendered [something] impure, or have themselves become pure, [in all three cases] they are pure; the uncertainty of the public domain [i.e. an uncertainty regarding purity status which was generated when something was in the public domain]; the uncertainty regarding [the purity status of something that came into contact with something that is impure only according to] the words of the Scholars; the uncertainty [regarding the purity status] of non-sanctified foods; the uncertainty regarding [the purity status of something which may have been rendered impure by] vermin; the uncertainty of blights [i.e. regarding the purity status of someone or something that may have been rendered impure by someone impure due to an illness, such as <i>tsara'at</i>]; the uncertainty regarding [one's] status as a nazerite [i.e. like someone who took a vow to be a nazerite contingent on something which remains uncertain]; the uncertainty regarding [the status of] a first born; and the uncertainty regarding [one's obligation to bring] sacrifices.
Bartenura on Mishnah Tahorot
English Explanation of Mishnah Tahorot
A doubt concerning drawn water for a mikveh,
A doubt concerning an object of uncleanness that floated upon the water.
A doubt concerning liquids as to whether they have contracted uncleanness it is deemed unclean, but if it was whether uncleanness has been conveyed it is deemed clean.
A doubt concerning the hands as to whether they have contracted uncleanness, have conveyed uncleanness or have attained cleanness, they are deemed clean.
A doubt that arose in a public domain;
A doubt concerning an ordinance of the scribes;
A doubt concerning non-sacred food;
A doubt concerning a sheretz;
A doubt concerning negaim;
A doubt concerning a nazirite vow;
A doubt concerning a first-born;
A doubt concerning sacrifices.
This mishnah introduces all sorts of cases of doubt where the sages ruled that something was clean. Except for the first case, the remainder of the list is explained from mishnah eight until the end of the chapter. Therefore, we will not explain these sections here.
Section one: If drawn water falls into a mikveh, the mikveh is disqualified. If there is a doubt whether this occurred, the mikveh remains valid.
Sections 2-12: These are explained in the following mishnayot. Stay tuned!