Arabic documents have been found that mention the times of the flooding, the methods for measuring this event, and Nilometers built by the Muslims to measure the increase and decrease of the Nile waters.
Taxes on agriculture produce were exacted based on the Nile's flooding.
The Arabs built channels, bridges, and canals for irrigation and farming. Celebrations and prayers to increase the water of the Nile were held inside the Mosque of Amr Ibn al-As, which had once overlooked the Nile.
Water played a lively role in religious Islamic rituals since it is connected with ablution, or ritual washing, which is necessary before prayer. The Mosque of Amr Ibn al-As and the Mosque of Ahmad Ibn Tulun were built close to the Nile.
Islamic architects added fountains inside mosques and schools so people could perform ablutions before praying, as found at the Mosque of Ahmad Ibn Tulun and the Mosque of Sultan Hassan. The sabil, or public fountain, provided passersby with water for drinking.
Sometimes, sabils were connected to mosques as in the Sultan Al-Mansur Qala'un Complex in al-Nahaseen, the brassmakers' quarter.
The distribution of water from the Nile to the public was very important to the Muslims. The uppermost part of the Walls of Sultan Salah al-Din, built to surround Cairo, was used as a channel from the Nile to transport water to the Citadel and Cairo.
The water was then distributed to different parts of a building using what is called the "Miqsam" of the Nile. This usually consisted of pottery pipes, such as those found in the excavations of the Al-Mansur Qala'un Complex. The pottery pipes were supported by stones outside the Madrassa of Sultan Hassan.
The architect might also distribute water through channels in the form of a U carved in stone, which continued throughout the wall to supply water to the kitchen, bathrooms, qa'as, or main halls, and basins.
The Nile influenced the urban development of Cairo, as the development of the capitals Al-Fustat, Al-Askar, and Al-Qata'i was limited in a south-north direction as the Nile prevented development toward the west.
Westward development only took place as the course of the Nile itself moved.
However, the present riverbank is only 500 meters or one-third of a mile west of the bank during the early days of Islam in Egypt.
The Nile also played an important role in the commercial life of Egypt. Ships carrying goods such as ceramics from China and Iran came from the Red Sea through Qabt, Qus, and Al-Qulzum on the Red Sea and reached the Nile from the east to Al-Fustat.
Ships also came from Europe and the Mediterranean Sea. Hotels were constructed on the banks of the Nile for travelers .