Someone who went down to immerse [in a mikveh], and there is an uncertainty as to whether he immersed or not, or an uncertainty as to whether it contained forty se'ah [a specific unit of volume] in it or it did not; or if there were two mikva'ot [gatherings of water collected by natural means and immersed in for purification], one with forty se'ah in it, and one without, and someone immersed in one of them but he does not know in which one he immersed, its uncertainty is impure [i.e. the case is uncertain and resolved as impure].

A mikveh which was measured and found to be lacking [the required forty se'ah of water], all purifications which were made upon it, whether in a private domain or in a public domain, are retroactively impure. To what [cases] does this apply? To a severe impurity [i.e something that was rendered impure by an Origin of impurity]. But with a light impurity, such as one who ate impure foods, or drank impure drinks, or one whose head and the majority of his body entered into drawn waters, or if three log [a specific measure of volume] of drawn water fell on one's head and the majority of one's body and one then went down to immerse; [in such a cases,] if there is an uncertainty as to whether he immersed or not, or even if he immersed, if there is an uncertainty as to whether it contained forty se'ah in it or it did not, or if there were two mikva'ot, one with forty se'ah in it and one without, and he immersed in one of them but does not know in which one he immersed, [in such cases,] its uncertainty is pure [i.e. the cases are uncertain and resolved as pure]. Rabbi Yose considers it impure, as Rabbi Yose says: Everything which has a presumption of impurity remains forever in its invalid state, until it becomes known that it was purified. But its uncertainty [regarding its ability] to become impure or to render [something else] impure, is pure [i.e. such cases are uncertain and resolved as pure].

Cases of uncertainty regarding drawn waters are considered pure by the Sages. [For example,] if it is uncertain whether they [the drawn waters] fell or did not fall [into a mikveh]; even if they did fall, if there is an uncertainty as to whether they [the waters of the mikveh] contained forty se'ah or did not; or if there were two mikva'ot, one mikveh containing forty se'ah and one not, and [drawn waters] fell into one of them and one does not know which it fell into, [in all these cases] its uncertainty is pure, because one has something upon which to hang [a presumption of purity]. If both [mikvaot] contained fewer than forty se'ah, and [drawn waters] fell into one of them and one does not know which it fell into, its uncertainty is impure [i.e. such a case is uncertain and resolved as impure], since one has nothing upon which to hang [a presumption of purity].

Rabbi Eliezer says: A revi'it [a specific measure of volume, a quarter of a log] of drawn waters render a mikveh invalid at the outset [i.e. if the waters were in the pit before the valid mikveh waters were added, as do as three log [of drawn waters which were added] on the surface of the [valid] waters. And the Sages say: whether at the outset [before there were any waters in the pit] or at the end [after valid waters amounting to less than forty se'ah were added], the measure [for the minimum amount of drawn waters to invalidate a mikveh] is three log.

Regarding a mikveh that has three furrows containing drawn waters [along its sloping side, such that each furrow is above the next], with one log in each, if it is known that forty se'ah of valid water fell in before they reached the third furrow, it is valid; and if not, it is invalid. Rabbi Shimon considers it valid because it is like a mikveh next to a mikveh.

One who removes the plaster [from the floor of mikveh] to the sides, and three log [of water] flowed from it [from the plaster], it is valid. If one removed [the plaster from the waters of the mikveh] and three log flowed out from it, it is invalid [since they are considered drawn waters]. And Rabbi Shimon considers it valid it because one did not intend to draw [the waters in such a case].

One who places jugs on the rooftop to dry them, and they filled with water, Rabbi Eliezer says: if it is the rainy season, or if there is [some] water in the pit [even if it is not the rainy season], one may break the jugs [such that their waters flow into the mikveh]; and if not, one should not break them [so that their waters flow in, since such waters would render the mikveh invalid, like drawn waters]. Rabbi Yehoshua says: either way, one may break or tip [them], but one may not pour [them] out.

The plasterer that forgot his pot in the pit and it filled with water, if the waters were floating in any amount over the top of it, one may break it [over the mikveh to add its waters, and it is not considered drawn water]; and if not, one may not break it [and add it, since such waters would be considered drawn, and thus invalid], according to Rabbi Eliezer. And Rabbi Yehoshua says: either way one may break it.

One who arranges jugs in a pit and they filled with water, even if the pit absorbed all its waters [such that the only water left in it was the water in the jugs], one may thereby break them [letting their water enter the mikveh, and it will still be valid, and not considered drawn water].

A mikveh containing water and plaster amount [together] to forty se'ah, Rabbi Eliezer says: one immerses [oneself or other items] in the water, and does not immerse in the plaster. Rabbi Yehoshua says: [one immerses both] in the water and in the plaster. In which plaster may one immerse? In plaster which water floats above. If the waters were on one side, Rabbi Yehoshua agrees that one immerses in the water and does not immerse in the plaster. Regarding which plaster was this said? Regarding plaster in which a reed descends into it by itself, according to Rabbi Meir. Rabbi Yehuda says: a place where [the plaster is thin enough that] a measuring stick will not stand [straight]. Abba Elazar ben Dolai says: a place where a [builder's] weight descends. Rabbi Eliezer says: that [plaster] which will descend into a barrel [with a narrow opening, when poured in]. Rabbi Shimon says: that which can enter the tube of a flask. Rabbi Elazar bar Tzadok says: that which can be measured with a log [i.e. a vessel with a wider opening, used for measuring a log].