The Saudis don't need water. Pathological anti-Semitism is apparently more than enough to slake their thirst:

Arab officials have rejected a UN proposal to set up a regional environmental training center in the Middle East because it would include Israel, a Saudi official said Wednesday. Prince Turki bin Nasser, Saudi official in charge of environmental affairs said the United Nations should establish an Arab-only environment training center instead. "Arabs do not need training from Israel," Turki said following one-day discussions of Arab League nations' environment ministers in Cairo. He added the Arab governments would discuss the proposal further with the UN Secretary-General Ban Ki-moon.

A quick dip into the MR archives suggests that - shockingly - the Arabs very much do need training from Israel:

Israel's nanotechnology program got a significant boost recently, with the first meeting of stakeholders in the Nanotechnology Clean Water Initiative. The Initiative - the result of combined efforts by Dr. Uri Sagman, Prof. Samuel Pohoryles and former prime minister Shimon Peres - has, for the first time, brought together major Israeli university researchers and global industry principals to work on nanotech-based solutions to the water shortage in the Middle East... From all reports, the Forum was a success, igniting practical interest among all its participants, and moving one step closer to Peres' vision of Israel as a world leader in nanoscience-based clean water technologies... if we build a society that emphasizes rationality, science, and technology rather than mysticism, violence, and death we can actually solve our problems instead of reverting back to primitive 9th century agrarianism.

Not even the Saudis are stupid enough to think that they wouldn't benefit enormously from Israeli technology and expertise. Which, by our count, leaves exactly one explanation for their refusal to accept aid from the Jewish State. This reminds us of the time that Iran rejected Israeli aid after their massive 2003 quake. And that other time when Pakistan rejected Israeli aid for a week and then made them smuggle it in through 3rd parties after their 2005 earthquake. And that other other time when the State Department rejected Israeli aid after Katrina. Self-destructive pathological anti-Semites.

References:
* 'Arabs do not need training from Israel' [JPost]
* Science and Progress Solve Stuff [MR]
* Figures. [MR]
* Pakistan Reluctant to Accept Israeli Disaster Aid, Just Like US State Department [MR]
* State Department Anti-Israel Ideology Gets Silly, Kills Americans [MR]

Previously:
* Anti-Semitism As Obsession (The "What Would Make You Care About That" Question)
* 'Arabs do not need training from Israel'
* Israeli Public Diplomacy Expert : British Boycott Is Vicious Anti-Semitism