I heard the Prophet ﷺ being asked about water in the open desert and the animals and beasts of prey that come to it. The Prophet ﷺ said, "When the water reaches the amount of two qullahs, it does not carry impurity."
حدثنا عبدة حدثنا محمد بن إسحاق عن محمد بن جعفر بن الزبير عن عبيد الله بن عبد الله
سمعت النبي ﷺ يسأل عن الماء يكون بأرض الفلاة وما ينوبه من الدواب والسباع فقال النبي ﷺ إذا كان الماء قدر القلتين لم يحمل الخبث
Its chain of transmission is sahih. Muhammad bin Jafar bin Zubayr bin Awwam was a trustworthy scholar, one of the jurists and Quran readers among the people of Madinah, and Bukhari mentioned him in al-Kabir, 1/1/54–56. Ubaydullah here is Ubaydullah bin Abdullah bin Umar bin Khattab, the full brother of Salim bin Abdullah, and he was a trustworthy successor. Tirmidhi related this hadith, 1:69–70, from Hannad, from Abdah bin Sulayman, with this chain of transmission. I have verified its soundness and its chains of transmission in my commentary on Tirmidhi, 1:97–99.Tirmidhi said, Abdah said, Muhammad bin Ishaq said, "The qullah is a large jar, the kind used for drawing water." In al-Nihayah it says, "The qullah is a large jug, the plural being qilal, and it is well known in the Hijaz." It then explains the qilal of Hajar by saying that Hajar is a village near Madinah, not the Hajar of Bahrain. These jars used to be made there, each one holding a waterskin's worth of water. It was called qullah because it is "qullat", meaning it is lifted and carried.