For months, citizens of this war-torn country have been terrorized by bomb explosions... Now another threat is growing, which could be just as deadly.

Yemenis are running out of water.

This poor Arabian Peninsula country has faced a severe scarcity of water for decades. But four months of fighting have dramatically worsened the situation, with attacks destroying water pipes, storage tanks and pumping facilities in a number of cities.

The number of Yemenis who lack access to drinking water has almost doubledsince the war began, according to the United Nations and aid agencies. Now, they say, more than 20 million people - about 80 percent of Yemen’s population - struggle to find enough water to quench their thirst and bathe.

Diseases such as malaria are spreading, killing hundreds of people, because so many residents are forced to use unsanitary sources of water, health experts say. The crisis is compounding a humanitarian emergency that already has prompted UN officials and aid workers to warn of famine.

If the shortages aren’t alleviated soon, there could be large-scale epidemics and many more deaths, said Ahmed Shadoul, the World Health Organization’s head of mission in Yemen.

"We expect a lot of people to die if the water situation remains unchanged," Shadoul said. "This is a catastrophic threat."

Many Yemenis are so desperate for water that they bathe with a damp cloth. During storms, people crowd into the streets to catch the rain in buckets. Going bald has become more popular, but not as a fashion statement.

"People are shaving their heads because they don’t have enough water to wash their hair," said Mubarak Salmeen, 58, who lives in Aden with his wife and five children.

This country has long experienced water shortages because of rapid population growth, a dry climate and government mismanagement of the water system. Environmental experts have predicted for years that Sanaa will be the world’s first capital to run out of water...

In recent months, an escalation in fighting has led to unprecedented disruptions in accessing water. Air raids,...and ground assaults have destroyed water infrastructure. In the southern port city of Aden, home to roughly a million people, most taps have run dry.

"The water situation is a disaster," said Najib Mohammed Ahmed, director of Aden’s water and sanitation authority.

The war pits Shiite rebels known as Houthis against supporters of President Abed Rabbo Mansour Hadi, whose government was toppled in February. A Saudi-led coalition launched a bombing campaign...the following month. Saudi Arabia maintains the rebels are a threat because they receive support from Iran, its regional foe.

The water problems go beyond the destruction of infrastructure. Power plants and electricity lines have been damaged in the fighting, hampering municipal authorities’ ability to pump water to residents. Diesel fuel for backup generators, which could be used to power the pumps, has become scarce, due to the difficulties of transporting it through war zones. In addition, UN officials and aid workers say an air and naval blockade established by the Saudi-led coalition is severely restricting imports.

Saudi officials deny they have choked off supplies of energy, saying that ships and aircraft are allowed to bring food and fuel into Yemen after undergoing inspections...

A life-changing shortage

The lack of water has transformed many Yemenis’ lives.

"It used to be that we would run for shelter when it rained. Now, if there’s rain, we all run outside with buckets," said Hussein bin Mohammed, 38, a pharmaceutical salesman from the southern city of Taiz.

The worsening shortages have sharply driven up the price of water in a country where the average resident earns a mere $122 a month.

Fuad Abdulrahman Ali, 53, an antiques salesman from Sanaa, said that prices had more than quadrupled for water trucked in from wells in surrounding villages.

"I never thought we’d be at the point of thinking about whether we can afford water," said Ali, a father of three.

Many people have no choice but to use unsanitary water for drinking, cooking and bathing. Wildcat drillers are boring wells and extracting untreated groundwater that they sell to consumers, health experts say. Residents are storing water for drinking and cooking in uncovered containers that become breeding grounds for mosquitoes that transmit malaria and dengue fever, according to the United Nations and aid agencies. In recent weeks, those organizations have identified at least 8,000 suspected cases of those diseases, far higher than the usual number.

"These containers at peoples’ homes have become a primary reason for the proliferation of mosquitoes that is causing large outbreaks of these diseases," said Alkhader Laswar, the Aden director for Yemen’s Health Ministry. In the city, he said, malaria and dengue fever have killed several hundred people.

Cholera and other water-borne diseases are also likely to spread as people use contaminated water. More than a million Yemenis have fled their homes for safer ground since March, with many of them cramming into schools and mosques, sharing crowded bathrooms and limited water supplies.

The United Nations says that 120,000 children could die if the lack of access to clean water, sufficient food and adequate health care persists. The fighting has forced many hospitals and medical clinics to close.

So far, about 3,500 people have been killed in the attacks.

"Children are dying of the current health conditions in the country much more so than before," said Julien Harneis, the Yemen representative for UNICEF.

The displacement of so many people carries other risks, such as aggravatingconflicts over decreasing supplies of water. Many people forced from home have sought refuge in rural areas with few wells and springs. According to pre-war statistics from the Yemeni government, disputes over water and land kill thousands of people each year.

"Now you have wells in these rural communities that are supplying water to 1,700 people instead of just 700," said Mohammed Shamsan, an adviser to the Ministry of Water and Environment. "This is frightening."

Ahmed al-Sanna has certainly seen a rise in demand for the water in his village, located in a sparsely populated area south of Taiz. Before the war, a trip to a local well would take less than half an hour. Now, the 46-year-old farmer said, the lines for water are so long that he has to wait seven hours to fill the containers that are hauled back home by the family’s donkey.

"The lines are becoming too long," Sanna said. "We don’t know what we’re going to do."