Abstract: The preserved heritage of al-Jabin, a town located in Yemen’s western highlands, offers a unique opportunity to document traditional water engineering principles. There are no springs in the immediate vicinity, because the town is perched at the edge of the mountain escarpment. Even today, water is provided by open cisterns that collect surface run-off following a rain. But as the rains needed to feed the system are highly unpredictable, the water supply is never secure. The perimeter wall of one of the cisterns bears a group of seven signs, a detailed description of which is given in Kitab Shams al-Ma`arif wa-Lata’if al-`Awarif, awork attributed to Ahmad ibn `Ali al-Buni (d. 1225), awell-known prolific writer on magic. Al-Buni explains that the signs symbolize God’s supreme name and thus display great magical power of a protective and well-wishing nature. Generally speaking, magical practices attempt to influence the course of natural events by calling upon a superhuman force. In the case of the cistern, God’s supreme name was inscribed in the hopes that this would lead to a guaranteed water supply. While it is easy to dismiss al-Buni’s text and the observed practice in al-Jabin as superstitious frailty, one needs to bear in mind that under life-threatening circumstances, even people in the modern West easily resort to magical procedures.