Boys play in a river in Pakistan. ( B.K.Bangash/Associated Press )

According to, 884 million people lack access to safe water supplies. Someone living in a slum may only get one-fifth of the amount of water a bathtub holds for their entire day’s needs. And every 20 seconds, a child dies from a water-related disease.

To raise awareness about the lack of clean drinking water, people around the world are celebrating the universal solvent today.

It’s World Water Day, an 18-year-old tradition of promoting the importance of keeping the world’s freshwater supply sustainable and healthful for humans. This year, the designated theme of the day is “Water and Cities.” The world’s cities are growing quickly, with 93 percent of city growth happening in poor or developing countries. Slums are expected to balloon by an average of 27 million people a year from 2005 to 2020. For that reason, infrastructure that supports accessible and sustainable freshwater is needed more than ever.

Events to raise awareness have been planned around the world, and easy ways to show support are popping up within the virtual realm.

On Twitter, I searched #worldwaterday and found facts, features and fun ways to learn about H2O:

What’s your footprint? National Geographic built a handy calculator to help you test your water footprint.

Save boiled water for houseplants? The National Wildlife Federation offers tips on conserving water in your home.

Watch and learn. See more about World Water Day 2011 at the U.N. World Water Day Youtube channel. Here’s Piers Cross, former manager of the Water and Sanitation Program in Kenya, talking about 2011’s theme:

@washingtonpost The last time I was grateful for water was this morning, when I poured a cool, tasty, unfiltered glass from the tap.less than a minute ago via webR.V. Scheide Jr.

@washingtonpost Actually, I’m thankful for water FILTERS because I live in a known hard water area.less than a minute ago via webBeth Gawthrop