Zevachim 25b: If one used a item that is mekabel tumah, such as his hand or foot, or vegetable leaves, to bring water to use for Parah Adumah (or for a mikveh – Rashi), it is posul… because the posuk says, “But a spring or a cistern, a pool of water shall be tahor” – it must come into being through taharah.
Yoreh Deah 201:48: A metal pipe may not be used to bring water into a mikveh, because it is mekabel tumah… but if it is connected to the ground, even if it flows directly into the mikveh, it is kosher, because it is no longer mekabel tumah since it is considered part of the ground.
זבחים כה ע”ב: תנן התם: נתן ידו או רגלו או עלי ירקות כדי שיעברו מים לחבית ־ פסולין, עלי קנים ועלי אגוזים. כשירהֹ זה הכלל: דבר המקבל טומאה ־ פסולין, דבר שאינו מקבל טומאה ־ כשירין. מנא הני מילי? דאמר רבי יוחנן משום רבי יוסי בר אבא, אמר קרא: (ויקרא יא) אך מעין ובור מקוה מים יהיה טהור, הוייתן על ידי טהרה תהא.
רש”י: הוייתן־ של מים המטהרים ע״י טהרה תהא כשאתה מהווה אותם להיות מקוה או קדוש הוי מהווה אותם על ידי דבר שאין מקבל טומאה.
יורה דעה ר”א, מח: וכן סילון של מתכת אסור להמשיך בו מים למקוה שמקבל טומאה והוא שיהיו המים נופלים להדיא מדבר המקבל טומאה לתוך המקוה אבל אם נופלים על שפתו בחוץ ונמשכין לתוכו או שמחבר לפי הסילון של אבר צנור קטן של עץ או של חרס שהמים מקלחין ממנה למקוה כשר ואם הסילון של מתכת מחובר לקרקע אפי׳ מקלח להדיא לתוך המקוה כשר שהרי אינו מקבל טומאה לפי שהוא בטל אגב קרקע.
When the Baba Sali came to live in the city of Boudenib, Morocco, he learned that the mikveh there was very old, and the women did not enjoy using it. He called a gathering of the board of the kehillah and asked them to build a new, beautiful mikveh that would be comfortable for the women.
They agreed to his request, and the mikveh was finished in the month of Tammuz. In that part of the world, it doesn’t rain in the summer, so the board members came to the Baba Sali’s house and informed him, “The mikveh is ready; we only have to wait until the month of Cheshvan, when it will rain and fill up the rainwater basin.”
But the Baba Sali wanted the mikveh to be usable as soon as possible. He lifted his eyes to the heavens and said, “Ribono Shel Olam, You commanded us to live in holiness and purity, and we want to follow Your command. We have done what we can; now You do what You can for the sake of Your holy name!”
As soon as he finished his prayer, even before the board members had left his room, a heavy rain miraculously began to fall, and the rainwater basin was filled up right away.
However, their joy was short-lived. A few hours later, as the Baba Sali examined the new mikveh, he noticed that the pipe through which the water ran into the basin was made of metal. Although it was kosher according to the Shulchan Aruch (YD 201:48) and most poskim, there was one stringent opinion, the Beis Yehuda, who held it is posul. The Baba Sali told them to empty the mikveh right away and install a new pipe made of wood, which is not mekabel tumah, saying, “I want a mikveh built according to the strictest standards.”
His talmidim protested and begged him to let go of this chumra, saying, “Not every day does a miracle happen. What’s the chance that another freak rainstorm will come right after the first one?” But he was as strong as a rock, and they had no choice but to follow his orders. They emptied the newly-filled basin and switched the metal pipe for a wooden one so that it would be kosher according to all opinions.
As soon as they finished fixing the mikveh, he turned to the heavens once again in prayer and said, “Holy Beis Yehuda! We followed you and declared the mikveh posul because of your shitah. I ask you to go to Hashem’s throne and ask Him to make it rain again for the sake of the taharah of the Jewish people, so that they can use the mikveh now.”
A short time went by, and, on that same day, rain poured down and filled up the rainwater basin again.
Source: Sefer Otzros Hatorah, Parshas Haazinu, volume 5
[According to the Shulchan Aruch, any pipe, even a metal one, that was attached to the building is considered not “mekabel tumah” and the mikveh is kosher. However, the Baba Sali wanted them to be machmir for the Beis Yehuda. Who is this Beis Yehuda, and why was he machmir? Some have suggested that he was referring to Rabbi Yehuda Ayash, a Sephardi posek whose Shailos Uteshuvos Beis Yehuda was published in 1746. However, I was unable to find a teshuva on this, or indeed any mikvaos subject, in the Beis Yehuda.
Perhaps there was a misprint in the story, and it should say Noda Beyehuda, who is in fact more machmir than the Shulchan Aruch on this point: In the Dagul Mervavah, he writes that attaching the pipe to the building only works if the pipe was manufactured for the purpose of attaching it to the building. Some poskim accept this chumra lahalacha, such as the Lechem V’simlah, the Mei Hashiloach, the Ksav Sofer and the Avnei Nezer. Others do not, such as the Chasam Sofer, the Beis Meir, the Divrei Malkiel, the Maharsham and the Gidulei Taharah.]
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