Although food is required to sustain life, water is the most important aspect. The human body can only sustain life for 3 days without water whereas you can live weeks without food. For this reason anyone who finds themselves in a survival situation may need to move to a location that can sustain life rather than hope that help finds them in an unsuitable location within a few days.
Understanding how the body uses and loses water is critical.

The human body loses water through normal body processes such as

Sweating
Urinating
Defecating

On average adults lose between 2 to 3 liters of water due to normal daily exertion at 70 degrees. Increases in temperature, intense activity, altitude or illness can cause your body to lose even more water. This water must be replaced.

Iodine tablets, drops, water purification filters and boiling water are all methods used to make drinking water safe for consumption.

There are several ways to find water depending on where you are located. For instance, it will be relatively easy to find water in the Pacific Northwest but not so easy in the desert. Generally speaking water will be found at the lowest point in the landscape. Moving down hill, rather than staying on top of a mountain or ridge, is the best way to find a suitable water source.

Of course, if you are in the desert there are other ways to find water that you should be aware of. Even in this harsh environment there is water. Look for green vegetation or river bottoms for signs of water. Digging in these areas can produce water. Of course, this is not a guarantee. However, making a still in these areas can provide you with a measurable amount of water. How much is impossible to tell.

SIDE HILL STILL

A ”Still” is a great way of getting water when there seems to be none available. Stills work by gathering condensation and collecting it in a cup. The side hill still is one of the easier stills to construct.

For an above ground still you will need:

Clear plastic bag.
Green leafy material
Cordage such as a shoe string or fishing line
Rock

Fill the bag half way to ¾ full of green leafy material. Do not use poisonous plants. Remove sticks or hard spines that might puncture the bag. Place the small rock into the bag. Tie the bag as close to the end as possible. Make sure there is as much air in the bag as possible. Place the bag on a sunny slope with the tied end facing downhill. Keep the end slightly higher to prevent water from escaping. Settle the bag in such a way that the rock works its way to the bottom of the bag.

To get the water out of the bag simply untie the end of the bag to get to the water that has collected around the rock.

This still can produce anywhere from .5 to 1 liter of water in a 24 hour period.

IN GROUND STILL

You will need a digging utensil, plastic, cup or water container and a drinking tube. Find a location for the still that you believe holds water such as a dry creek bed.

Dig a bowl shaped hole that it about 3 feet across and about 30 inches deep. In the middle of the hole dig a small sump for your water container. Take your drinking tube and place it in the cup. If you can secure the tube in the cup do so. Now, place your plastic over the hole. It needs to be loose enough to extend below ground by about 20 inches below ground level. Use rocks and soil to hold the plastic in place. In the middle of the plastic place a rock or object that will hold the plastic down. The point of the plastic, or apex, must be over the cup in order for this to collect water. You can drink directly from the tube without disturbing the still. If you don’t have a tube it will be necessary to partially dismantle the still in order to get the water.