In Iran, where there are no natural water sources for drinking. People harvest rainwater in a building with a pool and roof to protect the water from evaporating, animals and dust. This building is called 'Water Reservoir' in Iran's architecture. Water Reservoirs are also a part of 'Qanat Hydraulic System' that is a genius method for gathering fresh water in the desert. It is a combination of deep wells and an underground tunnel that gathers and brings the water to villages and towns and fills these water reservoirs. Water Reservoirs' architecture is very different in different places of Iran.
Central Desert- In the central desert, they have wind towers called 'Wind Catcher' in Iranian architecture. These towers are used in many buildings and they cool the rooms. In water reservoirs, wind towers cool the water and ventilate the air. The number of wind towers differs between 1 to 6 depending on the size of the reservoir and how much money has been paid to build them. To reach the water that is in the underground tunnel, people use stairs. Some of them are around 40 metres deep. There is a door for stairs that is usually decorated with tile work and arcs. A simple water Reservoir in central desert has a Dome, two wind towers, a door and stairs.
South of Iran- In South, water reservoirs get filled by rainwater, so the pool is on the ground and there is a dome on it. The dome has doors and windows. Some new ones have wind towers (e.g. Kish Island water reservoir). Local people call the water reservoirs 'Pool'. In some villages, they still use this water for drinking. The villages that are equipped by water pipeline, people use water reservoirs for their animals. Some of the abandoned water reservoirs have been changed to Cafes, restaurants and museums to keep the culture alive.
