Water, water, every where,
And all the boards did shrink ;
Water, water, every where,
Nor any drop to drink.

–“The Rime of the Ancient Mariner,” Samuel Taylor Coleridge

Water is essential for life. Without water, most people will die within three days or so (though some have survived longer). That’s because water makes up about 60 to 70 percent of a human’s body, by weight.

The average needs about two liters of water per day to replace water lost through urination (about 1.5 liters per day) and breathing, sweating and defecation (about 1 liter per day). (The daily requirement doesn’t add up to 2.5 liters because we get the remaining fluid from the food we eat.)

Water covers about 71 percent of the Earth’s surface, though most of that is saltwater, which people can’t safely drink. Lakes, rivers, streams and ponds that contain fresh water make up less less than 1 percent of the planet’s surface.

Water is a naturally occurring chemical substance. The water molecule is made of two hydrogen atoms bound together with one atom of oxygen. At sea level, water boils (transforms from a liquid to a gas) at 212 degrees Fahrenheit or 100 degrees Celsius. It freezes (transforms from a liquid to a solid) at 32 degrees Fahrenheit or 0 degrees Celsius.

While you need water to live, you also need to make sure your water is safe to drink. In 2005, contaminated water was responsible for the deaths of 4,000 children every day. Saltwater and urine aren’t good to drink, either: their high salt content makes your body want to put out more urine to get rid of the salt, leaving you thirstier and, eventually, at risk of dehydration.

Besides finding water in ponds, lakes and streams, you can collect water in the form of rain, condense water out of the air or dig below the ground’s surface to tap water held in permeable underground layers known as aquifers. You can draw water from such “wells” using either a pump (hand-powered or otherwise) or by drawing up buckets by hand.

There are many ways to purify water for drinking. You can:

  • Use water purification tablets;
  • Use a purifying powder known as PUR;
  • Boil water for at least one minute at sea level, preferably 10 minutes;
  • Collect dew or rainwater;
  • Build a condensation trap or solar still.

A solar still uses the sun’s heat to evaporate contaminated water, then condense it in a clean container for drinking and other uses. Review some of the following plans, decide which works best for you and print out the instructions as part of the appendix to this guidebook:

As an added reference, download and print the Wikipedia entry on water.