Can you think of a more profitable business than selling water in the desert? :)

Some Algerian regions have adopted Persian qanats. These are systems for extracting and distributing groundwater. They work purely on gravity. They likely started being used when Islam arrived in the region and continue to this day.

Usually, people pool together to build the system, then rent it out or sell shares. The distribution happens through a distributor (kasria), where each recipient gets a certain number of water outlets. Some people only need one.

Getting the right amount of water is actually really important. Date palms are the main crop here. If you give a palm tree too much water, the fruit becomes very watery and won't keep until the next season. But if you're too stingy, the dates end up very dry or won't ripen at all.

PS. Check out the unusual architecture of Timimoun. Houses in the surrounding villages are built from mud and stones, which gives them that distinctive red color. It gets scorching hot inside during the heat, but if you splash some water on the floor, it becomes much fresher and cooler.