In discussing the process of purification undergone by a Mesora (person stricken with Sara’at), the Torah in Parashat Mesora instructs that the Mesora must immerse in water in order to regain his status of purity (“Ve’rahatz Et Besaro Ba’mayim Ve’taher” – Vayikra 14:9). The Sefer Ha’hinuch lists this instruction as one of the 613 Biblical commands, establishing that immersion is required for one to become Tahor (pure) after having become Tameh (impure). The Rambam writes that a person who had become Tameh is not obligated to purify himself by immersing in a Mikveh; if he wishes, he may remain Tameh. It is only if he wishes to enter the area of the Bet Ha’mikdash or eat hallowed food that he is required to divest himself of his impure status through immersion. Nevertheless, the Sefer Ha’hinuch comments that pious individuals ensure to purify themselves and eliminate their status of Tum’a, because, in his words, “impurity is repulsive and purity is beloved.” As for the reason behind the concept of immersion as means of attaining purity, the Sefer Ha’hinuch offers two explanations. First, he writes, the Mikveh symbolizes the world in its incipient stages, at the beginning of creation, when it was filled with water. The impure individual is to see himself as being created anew, and thus he immerses in water and then emerges, just like the world was filled with water and then took shape. This sense of “re-creation” is to inspire the individual to begin a new chapter by breaking his bad habits and improving his conduct. Secondly, the Sefer Ha’hinuch explains, the immersion in a Mikveh represents a process of cleansing, and the experience is intended to motivate the person to “cleanse” himself spiritually through introspection and repentance. The Sages understood this verse in Parashat Mesora – “He shall bathe his flesh in water” – as indicating that one must immerse in an amount of water that covers the entire body. This amount has been determined by the Sages to be 40 Se’a of water. According to the opinion of Rav Haim Naeh (1890-1954), this equals 87.65 gallons. However, the Torah allows immersing also in a Ma’ayan – a natural fountain or spring – regardless of the quantity of water. As long as one’s body is entirely covered by the water of the Ma’ayan, the immersion is valid. As far as Torah law is concerned, “Mayim She’ubim” – rainwater which had been transferred from the place where it had initially fallen – may be used for immersion. However, the Sages enacted that any water which had been drawn with a utensil may not be used for a Mikveh. Even if rain fell into a utensil and it overflowed into a Mikveh, that water is invalid for immersion. Nowadays, in order to avoid the disqualification of “Mayim She’ubim,” there are two methods that are used in constructing Mikavot. One is called “Hazra’a,” whereby a cistern is filled directly with at least 40 Se’a of rainwater, and alongside it there is a Mikveh, with a hole in the wall between the cistern and the Mikveh. Then, water is added to the cistern containing rainwater, such that the water overflows through the hole into the adjoining Mikveh. Halacha allows adding “Mayim She’ubim” to a Mikveh once it had been filled with 40 Se’a of rainwater, and thus the overflow into the adjoining Mikveh is suitable for immersion. The second method is called “Hashaka,” whereby a cistern is filled with 40 Se’a of rainwater, and the adjoining Mikveh is filled with regular tap water. A hole is drilled through the shared wall, such that the two bodies of water are touching each other. Since the tap water in the Mikveh is touching the pure rainwater in the adjoining cistern, it is suitable for immersion. Many Mikvaot employ both methods, as each has certain Halachic advantages. A person who requires Tebila (immersion) must immerse without clothing. If a person immersed while wearing clothing, then the immersion is nevertheless valid, as long as the clothing was loose, such that the water came in dire