Washington (CNN) -- Nearly a billion people worldwide have limited access to clean water, the State Department says, and the crisis disproportionately affects women and girls.
"On average, women in developing countries walk 6 kilometers a day to collect water" because there is not enough of it nearby, Undersecretary of State for Democracy and Global Affairs Maria Otero told CNN.
The chore keeps girls out of school and women from more productive economic activities, Otero said.
Otero spoke at a Washington, D.C., event Wednesday organized to bring awareness to the issue.
Several hundred people gathered outside the State Department for the "Earth Day 6K Walk for Water," a 3.5-mile walk around the city to support the many women who have to carry containers on long treks every day to fetch water for their families. Nearly 1 billion people in the developing world walk on average 3.5 miles to get water to drink.
The United Nations' refugee agency estimates that more than half of the world's refugee camps don't have the recommended minimum daily water requirement of 20 liters per person, and about 30% of camps don't have adequate waste disposal and latrine facilities, according to its website.
Elynn Walter, the sustainability director with the Washington-based WASH Advocacy Initiative, which works to raise and funds and awareness to address the problem, said women in many developing countries are expected to supply water while men tend to other chores.
Walter stood before two large containers called jerry cans commonly used in third-world countries to carry water collected from far-away locations. When filled, she said the cans weigh a hefty 55 pounds.
"They often put it on their shoulder and carry it above their head," Walter told CNN.
Rachel Schneller, a foreign service officer who lived for two years in Mali in the mid-1990s as a Peace Corps volunteer, said she joined the walk to raise awareness about the problem. She lived in a village in a nut hut in Mali, with a grass roof, no running water and no electricity. She said she carried her water in a jerry can.
"When you need that water to do everything from washing your body, brushing your teeth, cooking your meals, washing your clothes, water for bathing ... you count every single drop, Schneller said. "You realize how important water is, especially if you're the one that has to go collect it and bring it back-- every single drop."
Secretary of State Hillary Clinton has elevated water to one of her key issues, providing $770 million through USAID in 2009 toward increasing access to water and sanitation, particularly for people living in developing countries.
Otero said water problems are not limited to the third world, however. Every region of the world is affected, including the United States, especially in the Southwest.
Water scarcity has even become a security consideration, she said.
"Wars can start, conflict can start, tension can happen, and being able to help countries manage this and address it in a collaborative way is part of our effort in working this," Otero said.
CNN's Jill Dougherty contributed to this report.