In the past, the life of the desert Ardestan could be sustained only by an excessive network of qanats, and even today they have preserved their importance. The Arvaneh Qanat is the largest and oldest of all. Its creation is attributed to the half-mythical Arvand Shah, allegedly the founder of the town itself. The qanat is certainly very old and dates from at least 2,500 years ago. Largely dependent on its water, the residents of the villages along its course jostled and quarreled about the amount of water that they could use, and many of these quarrels often ended up in bloody fights. This situation lasted until the 13th century. when a system of water distribution was devised by Nasir al-Din Tusl, the remarkable scientist in the Il-Khanid court. Many authorities, however, attribute the creation of this system to Sheikh Bahai. According to this system, every Village could use the water of the qanat only during definite hours of the day, which were counted by sundials. When the time was up, the water of the qanat was locked and reopened for the residents of another village. One sample of the allotment of water of the Arvaneh Qanat can be seen in the city park.
Another famous oanat, in the Mun district, is the world's only two-story qanat. Legend says that once a qanat-builder from Yazd stopped in Mun for a night. In the morning before departure, he told the locals that he had heard the murmur of underground waters and encouraged them to build a qanat on the site he had shown. On his way back, he stopped in Mun again and was very surprised to see that the qanat had been built on a difterent level from what he had suggested. The construction started anew, and another floor of the qanat came into being. Remarkably, the water of the two canals never mixes.