No rivers, no rain—what is Saudi Arabia’s secret water system?

Saudi Arabia is among the countries with the most limited natural water resources. More than 95 percent of its territory is desert, annual rainfall is generally below 100 millimetres, and summer temperatures can exceed 45°C.

According to a report by foreign media, the country has a population of more than 37 million, with most people living along the Red Sea and Persian Gulf coasts. Its inland regions consist largely of vast, dry deserts.

To overcome severe water shortages, Saudi Arabia has developed a vast water-supply network stretching from coastal areas deep into the desert. The system includes large pipelines that transport desalinated seawater to cities hundreds of kilometres away.

The pipelines are made of heavy-duty steel designed to withstand extreme desert heat, sand and underground pressure. Large pipelines can reach around 1.8 metres in diameter, while individual sections are typically 12 to 18 metres long. Before installation, the pipes undergo ultrasonic testing and receive special anti-corrosion coatings.

Modern surveying equipment is used to determine pipeline routes. Where rocks or mountainous terrain obstruct the route, controlled explosions are used to create deep trenches for laying the pipelines.

Desalination plants along Saudi Arabia’s coast form the backbone of the country’s water-supply system.

Seawater is first pumped through large intake pipes and then undergoes several treatment stages. It is initially treated using sand filters and chemical processes before passing through extremely fine filters.

The water is then forced through reverse-osmosis membranes at pressures of around 60 bar. These membranes remove salt and other contaminants from the seawater.

After desalination, essential minerals such as calcium and magnesium are added back to the water, while its acidity is adjusted to make it suitable for drinking.

Maintaining such a large-scale water-supply system is extremely expensive. Pipeline construction can cost millions of dollars per kilometre, while major desalination plants require investments running into hundreds of millions of dollars.

For Saudi Arabia, however, these costs are not simply a financial burden but a national necessity. With extremely limited natural freshwater resources, desalinating seawater and transporting it across the country has become a crucial part of its water infrastructure.