Ahmad ibn Muhammad, from Muhammad ibn Sinan, from Al-Hasan ibn Ribbat, narrated from Abu Abdullah عليه السلام: I asked Imam عليه السلام about a drain that is located above a well. Imam عليه السلام said: "If it is lower than the well, then the distance should be five cubits. If it is above the well, then the distance should be seven cubits from every direction. And that is sufficient."