Water reservoirs, or ab anbars as they are locally known, form the terminal end of extensive traditional water supply systems that make urban settlements possible in the Kavir desert region of Central Iran. Snow fed streams were tapped at the foothills of surrounding mountains and channeled through sloping subterranean canal systems (qanats), often over great distances to discharge into underground reservoirs within the city. These reservoirs were usually built at the center of city neighborhoods, and thus configure urban morphological form much in the same manner as their feeder canals (qanats) configure agricultural tract divisions. Hydrological, climatic and social criteria overlapped to evolve a distinct architectural form for these water reservoirs that now forms a distinct part of Yazd's architectural heritage and identity.
As is often with secular, public use structures, one cannot trace the precise origin or patron of most ab anbar reservoirs in Yazd. Though the earliest urban water supply constructions in Yazd are believed to date from the Sassanid period and many others have been continually repaired and used, most extant ab anbars can be today traced to the late Safavid and Qajar periods. The Shesh Badgiri anbar or 'Six wind catcher' reservoir was constructed in the Qajar period, while the Khan Bazaar anbar can be more accurately dated to Qajar ruler Nasr al-Din's reign. There are approximately 75-90 surviving anbars in Yazd today, and some of the important ones are the Seyed Va Sahra, Masoudi, Hadji Ali Akbari, Khajeh, Golshan, Rostam Geev, Kolah Doozha, Malekotojar and Mirza Shafi reservoirs.
The typical ab anbar consists of four key elements: the underground reservoir, the pasheer or platform, the dome, and the badgir or wind catcher shafts. Some of the larger and centrally located ab anbars also house a khazineh or public hot bath. The cylindrically shaped underground chamber often 10 meters below street level, maintain a stable low water temperature considerably below the summer sun baked ground surface. A descending staircase passageway approached the pasheer or foot of the faucet used to retrieve water. The semi-circular brick lined dome, visually much alike a Buddhist stupa, have escape vents in the center to cool water by air convection while protecting it from dust and other pollution. Four adjacent badgirs or weathering shafts, often at the cardinal directions would maintain fresh air circulation to prevent water quality deterioration. The hierarchy of urban space where anbars were sited would determine both its size and the scale of constituent elements. Thus, minor neighborhood anbars are usually endowed with fewer badgirs while larger, city center reservoirs are often serviced by six or more wind catchers. The access openings to the street were often decorated with intricate stalactite ornament while larger anbars often housed shops and coffeehouses in addition to public baths signifying an urban institutional status. Not infrequently bazaars, mosques, public baths and anbars would function together within a waqf (religious endowment) property. Ab anbars played a pivotal role in determining both Yazd's skyline and urban layout but are in a precarious state of preservation today with redundancy caused by modern piped water supply systems. Though few of the architecturally significant examples can be preserved, sustainable strategies to conserve traditional urban infrastructure systems like qanats, badgers, pigeon towers, dams and water mills need to be explored.
Bonine, Michael Edward. 1975. Yazd and it's Hinterland: A Central Place System of Dominance in the Central Iranian Plateau. University of Texas at Austin, Ph.D. Dissertation, 137.