Qanat of Zarch is the world's longest Qanat in the world which registered on Iran UNESCO World Heritage Sites under the name of The Persian Qanats.
Qanat of Zarch in Yazd dates back to pre-Islamic Era and according to some books it had been streaming across Yazd city about 700 years ago. Then people used water of Qanat of Zarch for sanitation purposes through Payabs (A place where water comes to the surface) and for drinking. The hydraulic structure of the Qanat is representative of its long history.
Zarch is a plain Qanat. The length of the gallery Qanat of Zarch is over 80 km. and the length of the mother well is 90m deep. It includes more than 1000 well shafts. Qanat of Zarch starts in Fahraj village in the northwest of Yazd and runs at the depth of 30_40 underground Yazd. In the end, it reaches Zarch and its water is used for irritation there in lower lands of Yazd. Qanat of Zarch has 3 branches that one Shur, means salty, is outside of the city and two others, Shakhe Shirin and Ebrahim Khoidaki, run into the city.
During the invasion of enemy forces when they blocked resources of waters, Qanat of Zarch was the only resource for the inhabitants. They had to climb down 70 steps to reach the water. The water of Shur branch tastes fresh in cold and a little bit salty in warm temperatures. The reason for its being salty is that the mother well is located in salty soil. Shur branch passes through Jameh Mosque of Yazd. Zarch Qanat enjoys myriad Payabs. Some of these Payabs are very old. Still, about 80 agricultural households use its water for irritation.
Presence of Zarch name not only in historical documents but also in myths and stories mentions to its long history. Thus, we can claim Zarch Qanat has a history as old as the city of Zarch itself. Zarch name has frequently been mentioned in various historical books.