In order to exploit rain and flood waters as efficiently as possible, the Ministry has concentrated on building several dams in various areas. Before 1975, there were 16 dams; the number had increased to 190 by 1999. These dams contribute to the increase of subterranean water reserves and the provision of potable water, as well as helping to protect plantations and some villages against the flooding which previously threatened them as a result of sudden torrential rises in the level of water.

The biggest dam is the King Fahd Dam in Bisha Valley with a capacity of 425 million cubic yards [325 million cu m]. Other dams include: Wadi Najran with a capacity of 111 million cubic yards [85 million cu m]; the dam of Wadi Jizan with a capacity of 98 million cubic yards [75 million cu m]; Wadi Taruba, Wadi Ekrimah and Wadi Yanbu, all with a capacity of 39 million cubic yards [30 million cu m] and the dam of Wadi Fatima on the outskirts of the Holy City of Makkah with a capacity of 26 million cubic yards [20 million cu m].