The essence of life, the need for water, is that much greater in arid regions. Water means life in the desert. Simply put, take twice as much as you think you'll need. A quart every half hour is a safe estimate, but ambient temperature, exertion, and length of hike are variables which should be anticipated beforehand. Carry at least one gallon of water per person per day and drink even when you don't feel thirsty.

Water is the key to life in the desert. It is a precious resource that requires special care. Camp well away (at least 200 feet) from water sources. Do not swim, wash, or rinse directly in potholes or small streams. Body oils, soaps, lotions, and sunscreens will pollute someone else's drinking water.

Avoid polluting water sources by using only clean cups or pots to dip with. Washing should be done at least 200 feet from running water and potholes. Use a minimal amount of soap, preferably a biodegradable type. Empty your wash water over sand or gravel or other filtering ground well away from the water source.

Since most desert animals are active at night and congregate around water, avoid camping near water and using water sources after dark. This way, you won't disturb the activities of thirsty wildlife.

Washing and Bathing

Never wash yourself, your children, your dishes, pets, or clothes directly in a water source. Doing so releases soaps, oils, food scraps, and other contaminants that disrupt the lives of organisms living there, or that use the water source. Carry water in a clean container at least 100 feet from the source and use biodegradable soap. Dispense dirty water in vegetated soil well away from the water supply. Remember that all soaps, even biodegradable soaps, pollute.

Swimming

Do not swim in or walk through potholes.

Potable Water

• Please don't wash in it.
• Wash dishes and yourself away from and below all sources of drinking water.
• Dispose of waste water away from lakes, streams, and springs.
• Boil or treat water before drinking it.

Most surface water is contaminated by animals or undesirable minerals and must be treated. Sometimes water sources will be muddy or clouded. Allow the sediment to settle, then carefully pour off the clear liquid and boil.

Bacteria

Water in some streams and lakes may be contaminated with bacteria or viruses that can make you sick. To avoid problems, boil the water before you drink it, use a viable filtration system, or carry all of your drinking water with you.

• See Amoebic Meningitis.
• See Giardiasis (Giardia lamblia).
• See Water Purification Filter.

Treating Water

When it becomes necessary to treat your drinking water, choose one of these options based upon your immediate needs and situation:

• Boiling—This works by basically cooking everything to death. If you own a stove or use a campfire, no extra investment is required, and it is foolproof. The down side is that it takes time and uses fuel, and it doesn't remove dirt. It is also inconvenient during a hike.
• Chlorine Dioxide (tables or drops)—This works because oxidization breaks down cell walls, deactivating the pathogens. This method is compact, economical, and kills everything. However, it sometimes requires a long wait and may leave some chemical taste.
• Filtration—This works by trapping pathogens in a microporous screen. This method is easy to maintain, you can feel the filter working, and there is no chemical taste. However, it does not trap viruses, it can clog, and it takes time to set up and pump. Depending on the model, the filter needs to be changed on some regular basis and they all need to be chemically cleaned from time to time.
• Iodine (tablets or crystals)—This works by deactivating bacteria and viruses. This method is compact, lightweight, and economical, but it leaves a chemical taste. There is also a wait time and it may be harmful to your thyroid (in high doses). Also, it does not kill cryptosporidium.
• Ultraviolet Light—This works by irradiating all microorganisms. This method is almost instant and is very user friendly. But, it is expensive and can't be repaired on the trail. The device is battery operated and won't work in murky water.

Always carry water in the car and on hikes.

If you run out of water in canyon country you may be able to extract potable liquid from some plants. In the Sonoran Desert regions you may be able to tap certain types of barrel cactus. But only do this in cases of extreme necessity. The liquid may taste bitter and the most cactus varieties are protected by law.

If you have no water at all you should walk at night and rest in the shade during the day. You may survive about five days if the daytime high temperature is 90 degrees, or three days if it hits 100 degrees.

On a long hike with no potable water your survival chances can increase greatly if you can build a solar still. To do this you must have two things: a six-foot-square sheet of thin, clear plastic and a container about the size of a cooking pot.

When you stop to wait out the sun, dig a circular hole about 40 inches wide and 20 inches deep, sloping down into a central cavity, where you put the container. The best place for the hole is a sunny spot in a sandy wash or depression where the soil may be damp.

If you can find succulent plants, cut them open to expose their moist interior and scatter them in the hole. Urine, saltwater, or anything else wet (except antifreeze) poured into the depression will also produce drinkable condensation.

Next, put the sheet of plastic over the hole and seal the edges tightly with soil or rocks. Finally, weight the center of the sheet until it is about two inches above the pot.

After an hour or two in the sun, the air trapped under the plastic will become saturated with water, condense on the sheet, and run into the pot. If you did things correctly, a solar still will produce about a quart of water per day. You would need two of these to keep one person alive indefinitely.

Note: Not all survival experts think that building a solar still is a good idea. Some argue that you'd sweat out as much water digging the hole as you'd generate with the contraption, and that the device must be precisely built to work.

• Collect Water in a Solar Still
  DesertUSA site.
• How to Create a Cheap Solar Still
• Solar Still