As a result, some 1.1 billion people worldwide lack access to water, and a total of 2.7 billion find water scarce for at least one month of the year. Inadequate sanitation is also a problem for 2.4 billion people—they are exposed to diseases, such as cholera and typhoid fever, and other water-borne illnesses. Two million people, mostly children, die each year from diarrheal diseases alone.

Many of the water systems that keep ecosystems thriving and feed a growing human population have become stressed. Rivers, lakes and aquifers are drying up or becoming too polluted to use. More than half the world’s wetlands have disappeared. Agriculture consumes more water than any other source and wastes much of that through inefficiencies. Climate change is altering patterns of weather and water around the world, causing shortages and droughts in some areas and floods in others.

At the current consumption rate, this situation will only get worse. By 2025, two-thirds of the world’s population may face water shortages. And ecosystems around the world will suffer even more.

Women and children are the most affected — children because they’re more vulnerable to diseases caused by dirty water and women and girls because they often bear the burden of carrying water for their families for an estimated 200 million hours each day.

Access to clean water changes everything; it’s a stepping-stone to development. When people gain access to clean water, they’re better able to practice good hygiene and sanitation. Children enjoy good health and are more likely to attend school. Parents put aside their worries about water-related diseases and lack of clean water access. Instead, they can water crops and livestock and diversify their incomes. Communities no longer vie for rights to a waterhole.