Ab Anbar Reservoir

 

Ab Anbar Reservoir

 

An ab-anbar is a traditional type of reservoir that was commonly built in pre-modern Iran. Aboveground, an ab-anbar can be recognized by its distinctive domed profile, often studded with two or more bad-gir (windcatchers) that provide ventilation.

Ab-Anbars were often constructed by first digging a cylindrical or sometimes rectangular tank deep into the ground--sometimes as far as twenty meters. The walls of the tank were lined with bricks using a special type of mortar called sarooj that was considered to be completely impermeable to water. The tank was then covered with a dome that protected the water in the tank from evaporation and contamination from windborne dust and bird droppings. The windcatchers that projected from the dome allowed for dry desert air to flow into and out of the dome, performing the dual functions of cooling the water and preventing condensation from forming on the inside of the dome, which could potentially lead to mildew and other hygenic concerns.
Purity of the water was further maintained by isolating the main tank entirely from human contact. Water could only be obtained from the cistern by descending a series of steps runnning adjacent to the tank. Taps near the top of the stairs provided warmer water, while the coolest water could be obtained by descending to the bottom of the stairs and extracting water from taps at the base.
Ab-anbars were so important to life in desert regions that they often became integrated into structures built atop them, such as caravanserais or mosques.