Attacks on water systems are uncommon in wartime, but Iran has threatened to target desalination plants after it said its own water and energy infrastructure had sustained damage in the ongoing war with Israel and the US.

What has Iran said?

Iran's military renewed its threats on Sunday against the region's infrastructure after US President Donald Trump vowed to "obliterate" power plants in the Islamic republic if the Strait of Hormuz was not swiftly reopened.

"Following previous warnings, if Iran's fuel and energy infrastructure is violated by the enemy, all energy, information technology and desalination infrastructure belonging to the US and the regime (Israel) in the region will be targeted," the Iranian military's operational command Khatam Al-Anbiya said in a statement carried by the Fars news agency.

The statement came after Trump gave Iran a 48-hour deadline to open the vital route in the Gulf to shipping traffic after it was effectively closed early in the Middle East war.

- Who was previously targeted? -

Bahrain's interior ministry said on March 8 that an Iranian drone attack damaged a water desalination plant, accusing Tehran of "randomly" targeting civilian infrastructure.

The country's national communications office later said the Iranian attack had no impact on water supplies or network capacity.

The strike came a day after Iran accused the United States of setting a precedent by attacking a desalination plant on Qeshm Island that supplies 30 villages.

Iran's Revolutionary Guards said the United States attacked Qeshm from a base in Bahrain.

Iranian energy minister Abbas Aliabadi said Sunday that attacks had "targeted dozens of water transmission and treatment facilities and destroyed parts of critical water supply networks".

Belligerents going after water supplies risks triggering "a war far more enormous than the one we have today", water economist Esther Crauser-Delbourg told AFP earlier in March.

Why does desalinated water matter?

The Middle East is among the driest regions in the world, with water availability about 10 times lower than the global average, according to the World Bank.

That makes desalination plants essential to the economy and drinking water supplies in the region.

About 42 percent of the world's desalination capacity is located in the Middle East, according to a study published in the journal Nature.

Desalinated water provides 42 percent of drinking water in the United Arab Emirates, 70 percent in Saudi Arabia, 86 percent in Oman and 90 percent in Kuwait, according to a 2022 report from the French Institute of International Relations think tank.

"Over there, without desalinated water there, there is nothing," said Crauser-Delbourg.

The supply is particularly strategic for large cities such as Dubai and Riyadh.

As far back as 2010, the CIA warned that disrupting desalination facilities in most Arab countries "could have more serious consequences than the loss of any other industry or commodity".

A 2008 US diplomatic cable published by WikiLeaks said Riyadh might have to evacuate within a week if the Jubail desalination plant or its pipelines were severely damaged.

What threats do the plants face?

Besides military strikes, desalination plants are vulnerable to power outages and contamination of seawater, including oil spills, according to experts.

"We have strengthened access security and controls in the immediate vicinity of the plants," said Philippe Bourdeaux, regional director for Africa and the Middle East at French firm Veolia.

The company supplies desalinated water to regions including Jubail in Saudi Arabia, and Muscat, Sur and Salalah in Oman.

"The recent events are of course prompting us to be extremely vigilant," Bourdeaux said.

"In some countries, authorities have placed missile batteries around the largest plants to counter the drone or missile threat," he added.

Operators also have tools to limit damage from oil spills.

What are the precedents?

There have been few other attacks on desalination facilities over the past decade.

Iran-backed Houthi rebels in Yemen have targeted desalination plants in Saudi Arabia in the past, while a Saudi-led coalition has struck back at water infrastructure in Yemen, according to the Pacific Institute, which tracks water-related conflicts.

Israeli strikes have hit water infrastructure in the Gaza Strip, according to the institute.

Before 2016, similar attacks date back to the Gulf War in 1991.

What if attacks escalate?

The impact could range from short disruptions to far more severe consequences if outages last.

"We could potentially see major cities facing an exodus. And rationing," Crauser-Delbourg said.

Water shortages could also ripple through the economy, hitting tourism, industry and data centres, which consume large amounts of water for cooling.

Some safeguards exist, Bourdeaux said. Desalination plants are often interconnected, which can limit the impact if one facility shuts down.

Most also hold reserves equivalent to two to seven days of water consu