A qanāt (Persian: قَنَات) or kārīz (کَارِیز) is a system used to bring water from underground sources, such as aquifers or wells, to the surface through an underground channel. It was created about 3,000 years ago and is used in many places across Asia and North Africa, though it is called by different names in different regions. For example, it is known as kārēz in Afghanistan and Pakistan, foggāra in Algeria, khettāra in the Atlas Mountains, daoudi-type falaj in Oman and the United Arab Emirates, and ʿuyūn in Saudi Arabia. The largest working qanats today are found in Iran, Afghanistan, Xinjiang in China (the Turpan water system), Oman, and Pakistan. These systems were also used in parts of Europe during the Roman Empire and later in Muslim-ruled Spain, which helped spread their use to parts of the Americas. Some experts believe similar systems may have existed in the Americas before European arrival.
Qanats are important in hot, dry areas because they move water over long distances while reducing evaporation. They are also less likely to be damaged by natural events like floods or earthquakes, or by human actions such as wartime destruction or attacks on water supplies. Additionally, they work well even when rainfall changes, providing a steady flow of water even during dry years.
A qanat usually includes a tunnel that slopes gently and is entered through vertical shafts that look like wells. This design allows groundwater to flow to the surface through gravity, without needing pumps. The vertical shafts are used for maintenance, and water is only used after it reaches the surface.
Today, qanats still provide reliable water for drinking and farming in hot, dry, and semi-dry regions. However, their usefulness depends on the quality, amount, and consistency of groundwater in an area. Since ancient times, qanats have been vital for many communities outside of Iran, and many long-inhabited areas in West Asia and North Africa are located in places where qanats could be built and maintained.
Etymology
The word "qanat" comes from Akkadian, where the word "qanû(m)" means "reed." This refers to the reed beds that grew in the marshes of southern Mesopotamia. The Hebrew term "qāne" means "wild reed plant" or "tube-shaped stick." In Arabic, the word "qanāh" (قناة) means "spear" or "channel." In Persian, two words are used: "kārīz" or "kārēz" (کاريز), which comes from the earlier word "kāhrēz" (کاهریز), and "qanāt" (قنات). Other names for qanat include "kahan" (Persian: کهن), "kahn" (Balochi), "kahriz/kəhriz" (Azerbaijan), "khettara" (Morocco), "galerías, minas, or viajes de agua" (Spain), "daoudi-type falaj" (Arabic: فلج) (United Arab Emirates and Oman), and "foggara/fughara" (North Africa). In Asia and North Africa, other names for qanats include "kakuriz," "chin-avulz," and "mayun."
The Oxford English Dictionary says the origin is "Persian, from Arabic qanät 'reed, pipe, channel.'" Common English variations of "qanat" include "kanat," "khanat," "kunut," "kona," "konait," "ghanat," "ghundat," and "quanat."
Origins
Qanat technology was created by ancient Iranians around the early 1st millennium BCE and spread west and east over time. Some sources say it may have started in Southeast Arabia. Similar water systems were developed separately in China and southern Peru.
A cotton plant called Gossypium arboreum is native to South Asia and has been grown in the Indian subcontinent for many years. Cotton is described in ancient writings like Theophrastus’s Inquiry into Plants and the Laws of Manu. As trade routes expanded, cotton moved from South Asia to the Middle East. One idea is that qanats were built to water cotton fields in what is now Iran, doubling the water supply for farming and cities. This helped Persia produce more food, leading to more cities and greater differences in social classes. Later, qanat technology spread from Persia west and east.
In Peru’s dry coastal desert, a water system similar to qanats called puquios was developed. Most archaeologists believe puquios are native to the region and date to around 500 CE. A few think they were introduced by Spanish people in the 16th century. Puquios were still used in the Nazca region as recently as the 21st century.
Features
Underground Aqueducts Handbook (2016)
Qanats are built using a series of vertical shafts, connected by a gently sloping tunnel that holds a water canal. Qanats move large amounts of underground water to the surface without needing pumps. The water flows by gravity, usually from an aquifer in higher areas, to a lower destination. Qanats help transport water over long distances in hot, dry climates with little water lost to evaporation.
Qanats often begin below mountain foothills, where groundwater is close to the surface. The tunnel slopes gently downward, matching the land’s slope above, until the water flows out where the two levels meet. To bring water to populated or farming areas, qanats may stretch for long distances.
Sometimes, qanats are divided into smaller underground canals called kariz. These canals stay underground to prevent water from evaporating or getting dirty. In some cases, qanat water is stored in reservoirs, with nighttime water saved for use during the day. An ab anbar is a traditional Persian reservoir that uses qanat water for drinking.
Qanats are strong against natural disasters like floods and wartime damage. They also work well in areas with little rain, as their water flow changes slowly between wet and dry years. Since qanats rely only on gravity, they have low costs for operation and repair. They move fresh water from mountain plateaus to lower plains with salty soil, helping reduce soil saltiness and prevent desertification.
Qanats should not be confused with spring-flow tunnels found near Jerusalem. Both use tunnels to move water by gravity, but they differ in key ways. First, qanats began as artificial springs made from wells, while spring-flow tunnels were created by improving natural springs after groundwater levels dropped. Second, qanats require vertical shafts for construction, but spring-flow tunnels do not.
Impact on settlement patterns
In many towns and cities in Iran and other places where qanats are used, there are multiple qanats. Fields and gardens are often found above the qanats, just before they come out of the ground. They are also located below the surface outlet. The water from qanats helps shape the areas where people live and the way cities are built.
The water is cleanest, coolest, and freshest in the upper parts of the qanat. Wealthier people usually live near the outlet or just above it. Before the qanat reaches the surface, water is brought up through wells or Persian wells powered by animals. Private underground reservoirs can provide water for homes, buildings, and gardens. Air from the qanat is used to cool a special room in older homes called a shabestan, which is used during hot summers.
After the qanat exits the ground, water flows through open canals called jubs, which run downhill. These canals have side branches that carry water to neighborhoods, gardens, and fields. Streets in cities often follow the path of the jubs and their branches. This means cities are built to match the slope of the land, which helps distribute water efficiently across different areas.
The lower parts of the canals are less suitable for homes or farming. Water becomes dirtier as it moves downstream. In dry years, the flow of water in these areas decreases the most.
Construction
Traditionally, qanats are built by a group of skilled workers called muqannīs using hand tools. This job was historically well-paid and often passed from father to son.
The first step in building a qanat is finding a suitable water source. Workers look near where mountain areas meet flat, sandy regions called alluvial fans because water is more plentiful in mountains due to natural weather patterns. They follow paths of water flowing from mountains to find signs of underground water, such as plants with deep roots or wet spots. A test well is dug to check the depth of the water and whether enough water flows to make construction worthwhile. If these conditions are met, the path for the qanat is planned above ground.
Tools needed include leather bags, ropes, reels to lift materials, hatchets, shovels, lights, and tools to measure levels. Depending on the soil type, clay rings may also be used to line the qanat.
Although the methods are simple, building a qanat requires knowledge of underground geology and careful planning. The slope of the qanat must be just right: too flat and water won’t flow, too steep and erosion could collapse the qanat. Mistakes in understanding the soil can cause collapses, which may require major repairs or harm workers.
A team of 3–4 muqannīs usually builds a qanat. For shallow qanats, one worker digs the horizontal tunnel, one lifts the dirt to the surface, and one spreads the dirt at the top.
Construction often starts at the destination where water will be delivered and moves toward the water source. Vertical shafts are dug along the route, spaced 20–35 meters apart. The spacing balances the effort needed to dig the shafts and the space between them. In shallow qanats, shafts are closer together. Long qanats may be dug from both ends at the same time. Additional channels may be built to increase water flow.
Most qanats in Iran are less than 5 kilometers long, though some near Kerman are up to 70 kilometers. Vertical shafts are typically 20–200 meters deep, with some in Khorasan reaching 275 meters. These shafts support the underground channel, provide air, and help with maintenance. Deep shafts may need platforms to remove dirt.
Construction speed depends on the depth and type of soil. In soft soil, a team of four workers can dig 40 meters of horizontal tunnel daily at 20 meters depth. At 40 meters depth, they may only dig 20 meters per day, and at 60 meters, less than 5 meters. In Algeria, digging 2 meters per day at 15 meters depth is common. Long qanats can take years or even decades to complete.
Dirt is usually moved in leather bags up vertical shafts and piled around the shafts to block wind or rain. These piles may be covered for extra protection. From above, the shafts look like a series of craters.
The qanat’s underground channel must slope downward enough for water to flow easily. However, the slope must not be too steep, as this can cause dangerous water waves that erode the qanat. A balance is needed between erosion and sediment buildup. Steeper slopes increase erosion, while flatter slopes require more cleaning. Short qanats have slopes of 1:1000 to 1:1500, while longer ones may be nearly flat. Tools like spirit levels and string help achieve this precision.
In steeper areas, underground waterfalls may be built with special linings to reduce erosion. In some cases, water power has been used to run underground mills. If the qanat’s outlet cannot be near a settlement, an open channel called a jub may be built above ground, though this is avoided to reduce water loss and pollution.
Vertical shafts may be covered to keep out sand. The qanat’s channels must be regularly checked for damage, cleaned of dirt, and repaired. Before entering, air flow must be confirmed for safety.
Some damaged qanats have been restored. Restoration requires considering factors like groundwater availability, community support, and water rights. In Syria, three qanats were chosen for restoration based on a 2001 survey. One, the Drasiah qanat, was completed in 2002. Criteria included steady water flow, community cooperation, and a working water rights system.
Applications
Qanats are primarily used for irrigation, giving water to animals, and providing drinking water. Other uses include watermills, cooling systems, and storing ice.
Watermills connected to qanats needed to be placed carefully to use the slow water flow effectively. In Iran, underground mills were found in Yazd and Boshruyeh. At Taft and Ardestan, mills were built near the end of the qanat, where water flowed out before being used to water crops.
Qanats can work with wind towers to cool buildings and supply water. A wind tower is a tall, chimney-like structure above a house. One of its four openings faces away from the wind to push air out. Cool air is pulled from a qanat below the house. As air moves through the tower, pressure changes (Bernoulli effect) draw cool air from the qanat tunnel, mixing it with the incoming air.
The air from the qanat enters a tunnel far from the house. It cools by touching the tunnel walls and water, and by heat being absorbed as water evaporates into the air. In dry deserts, this can lower the air temperature by more than 15°C. The mixed air remains dry, keeping the basement cool and only slightly moist. Wind towers and qanats have been used to cool homes in deserts for over 1,000 years.
By 400 BCE, Persian engineers learned how to store ice in summer in the desert. Ice was sometimes brought from nearby mountains during winter. More often, they built a wall facing east-west near a yakhchal (ice pit). In winter, qanat water was directed to the north side of the wall, where shade helped water freeze faster, creating more ice each day. The ice was stored in yakhchals—special underground storage areas with thick walls and windcatchers. These structures used wind towers to pull cool air from the qanat, keeping the ice cold even in summer. This allowed ice to last all year.
By country
Qanats, called foggaras in Algeria, provide water for irrigation in large oases like Gourara. Foggaras are also found in Touat, an area of Adrar 200 km from Gourara. The foggaras in this region are estimated to be thousands of kilometers long. Although some sources suggest foggaras may have been used as early as 200 CE, they were definitely in use by the 11th century. This happened after the Arabs took control of the oases in the 10th century and the people there adopted Islam. Water is distributed to different users through weirs, which control the flow of water into separate canals for each user.
The humidity in the oases helps add more water to the foggaras. The temperature difference in the vertical shafts causes air to rise naturally, creating a draft that enters the foggaras. Moist air from the agricultural areas moves into the foggaras in the opposite direction of the water flow. Inside the foggaras, the air condenses on the tunnel walls and exits through the vertical shafts. This condensed moisture can be reused.
Qanat irrigation technology was introduced to Egypt by the Achaemenid king Darius I during his reign from 522–486 BCE, as noted by historian Albert T. Olmstead. There are four main oases in the Egyptian desert. The Kharga Oasis has been studied extensively. Evidence shows that qanats were used to bring water as early as the second half of the 5th century BCE. The qanats were dug through water-bearing sandstone, allowing water to seep into the channels. Water collected in a basin behind a small dam at the end of the qanat was used to irrigate fields. The qanat’s width was about 60 cm (24 in), and its height ranged from 5 to 9 m (16 to 30 ft). It is likely that the qanat was deepened to increase water seepage when the water table dropped, similar to practices in Iran.
Another structure in the Kharga Oasis was a well that dried up. Workers improved it by digging a side shaft through sandstone into the hill of Ayn-Manâwîr. After extending the side shaft, a vertical shaft was added to connect with it. Side chambers were built, and holes were drilled into the rock where water seeped from the rocks.
David Mattingly reported that foggara systems in the Garamantes area of Libya extended for hundreds of miles. The channels were narrow, less than 2 feet wide and 5 feet high, but some were several miles long. About 600 foggara systems stretched for hundreds of miles underground. Workers dug and maintained the channels using vertical shafts spaced about 30 feet apart, totaling 100,000 shafts. The shafts averaged 30 feet in depth, though some reached 130 feet.
In southern Morocco, qanats, called khettaras, have been used for irrigation since the late 14th century. In Marrakech and the Haouz plain, qanats were abandoned in the 1970s because they dried up. In the Tafilaft area, half of the 400 khettaras are still in use. The construction of the Hassan Adahkil Dam in the Ziz River in 1971 and its impact on local water levels is one reason for the decline of khettaras.
The Black Berbers (Haratin) of southern Morocco were the hereditary group responsible for digging and repairing qanats. Their work was dangerous.
In Tunisia, the foggara system, similar to the Iranian qanat, is used to create oases. Foggara tunnels are dug into the foothills of steep mountain ranges, such as the eastern Atlas Mountains. Rainwater in the mountains flows into aquifers and moves toward the Sahara. The foggara tunnels collect water from the aquifers. Families maintain the foggara and own the land it irrigates, which is about 10 meters wide. The length of the foggara depends on the size of the plot the water can irrigate.
Qanats are called kariz in Dari (Persian) and Pashto. They have been used since before the Islamic period. It is estimated that over 9,370 karizes were in use in the 20th century. The oldest functional kariz, more than 300 years old and 8 kilometers long, is in Wardak province and still provides water to nearly 3,000 people.
Many ancient qanats were destroyed during the Soviet-Afghan War and the War in Afghanistan. Maintenance has become difficult due to high labor costs and a lack of skilled workers. Some large farmers have abandoned their family-owned karizes and switched to using tube wells and diesel pumps. The Afghan government, along with local and international groups, has worked to repair and maintain karizes. In 2009, functional qanat systems still existed. However, American forces accidentally damaged some channels during the expansion of a military base, causing tensions with local communities. Some tunnels were used to store supplies and move people underground.
Qanats are preserved in Armenia in the village of Shvanidzor, near the Iranian border. They are called kahrezes in Armenian. There are five kahrezes in Shvanidzor. Four were built before the village was founded, and the fifth was built in 2005. Three of the kahrezes provide drinking water, while two are in poor condition. Water levels drop to their lowest in July and August, causing water shortages. Kahrezes remain the main source of drinking and irrigation water for the community.
In Azerbaijan,
Symbolism in Iranian culture
On August 21, 1906, Florence Khanum, the wife of an Iranian diplomat named Ali Kuli Khan, wrote a letter from Tehran. In it, she described how qanats were used to water the garden at the home of her brother-in-law, General Husayn Kalantar, in January 1913. This information is noted in Arches of the Years (1999).
In Iran, an old tradition involved ceremonies where a widow would symbolically marry a qanat. This practice was thought to help keep the qanat’s water flowing continuously.