“This is concerning my question before abu ‘Abd Allah (a.s.), about the case of a people whose water fountains in a land are near each other, one of them decides to make his fountain below its original place in which case is harmful to the other fountains but certain ones do not harm due to solidity of earth. He (the Imam) said, ‘Whatever is in solid land it does not harm but whatever is in soft land and sandy, it harms. One can ask his neighbor to keep his fountain at the same level as his and if they agreed it does not harm.’ He (the Imam) said, ‘The distance between two fountains must be kept at one thousand Dhira‘ (hands or arms length).”’