4-1. To survive, you need water and food. You must also have and apply high personal hygiene standards.
4-2. Your body loses water through normal body processes (sweating, urinating, and defecating). During average daily exertion when the atmospheric temperature is 20 degrees Celsius (C) (68 degrees Fahrenheit [F]), the average adult loses and therefore requires 2 to 3 liters of water daily. Other factors, such as heat exposure, cold exposure, intense activity, high altitude, burns, or illness, can cause your body to lose more water. You must replace this water.
4-3. Dehydration results from inadequate replacement of lost body fluids. It decreases your efficiency and, if you are injured, it increases your susceptibility to severe shock. Consider the following results of body fluid loss:
A 5-percent loss results in thirst, irritability, nausea, and weakness.
A 10-percent loss results in dizziness, headache, inability to walk, and a tingling sensation in the limbs.
A 15-percent loss results in dim vision, painful urination, swollen tongue, deafness, and a numb feeling in the skin.
A loss greater than 15 percent may result in death.
4-4. The most common signs and symptoms of dehydration are—
Dark urine with a very strong odor.
Low urine output.
Dark, sunken eyes.
Loss of skin elasticity.
Delayed capillary refill in fingernail beds.
Trench line down center of tongue.
Thirst. (Last on the list because you are already 2-percent dehydrated by the time you crave fluids.)
4-5. You should replace the water as you lose it. Trying to make up a deficit is difficult in a survival situation, and thirst is not a sign of how much water you need.
4-6. Most people cannot comfortably drink more than 1 liter of water at a time. So, even when not thirsty, drink small amounts of water at regular intervals each hour to prevent dehydration.
4-7. If you are under physical and mental stress or subject to severe conditions, increase your water intake. Drink enough liquids to maintain a urine output of at least 0.5 liters every 24 hours.
4-8. In any situation where food intake is low, drink 6 to 8 liters of water per day. In an extreme climate, especially an arid one, the average person can lose 2.5 to 3.5 liters of water per hour. In this type of climate, you should drink 8 to 12 ounces of water every 30 minutes. It is better to regulate water loss through work or rest cycles because overhydration can occur if water intake exceed 1 1/2 quarts per hour. Overhydration can cause low serum sodium levels resulting in cerebral and pulmonary edema, which can lead to death.
4-9. With the loss of water there is also a loss of electrolytes (body salts). The average diet can usually keep up with these losses but in an extreme situation or illness, additional sources need to be provided. You should maintain an intake of carbohydrates and other necessary electrolytes.
4-10. Of all the physical problems encountered in a survival situation, the loss of water is the most preventable. The following are basic guidelines for the prevention of dehydration:
Always drink water when eating. Water is used and consumed as a part of the digestion process and can lead to dehydration.
Acclimatize. The body performs more efficiently in extreme conditions when acclimatized.
Conserve sweat, not water. Limit sweat-producing activities but drink water.
Ration water. Until you find a suitable source, ration your sweat, not your water. Limit activity and heat gain or loss.
4-11. You can estimate fluid loss by several means. A field dressing holds about 0.25 liters (1/4 canteen) of fluid. A soaked T-shirt holds 0.5 to 0.75 liters.
4-12. You can also use the pulse and breathing rate to estimate fluid loss. Use the following as a guide:
With a 0.75-liter loss the wrist pulse rate will be under 100 beats per minute and the breathing rate 12 to 20 breaths per minute.
With a 0.75- to 1.5-liter loss the pulse rate will be 100 to 120 beats per minute and 20 to 30 breaths per minute.
With a 1.5- to 2-liter loss the pulse rate will be 120 to 140 beats per minute and 30 to 40 breaths per minute. Vital signs above these rates require more advanced care.
4-13. Although you can live several weeks without food, you need an adequate amount to stay healthy. Without food your mental and physical capabilities will deteriorate rapidly and you will become weak. Food provides energy and replenishes the substances that your body burns. Food provides vitamins, minerals, salts, and other elements essential to good health. Possibly more important, it helps morale.
4-14. The three basic sources of food are plants, animals (including fish), and issued rations. In varying degrees, both provide the calories, carbohydrates, fats, and proteins needed for normal daily body functions. You should use rations to augment plant and animal foods, which will extend and help maintain a balanced diet.
4-15. Calories are a measure of heat and potential energy. The average person needs 2,000 calories per day to function at a minimum level. An adequate amount of carbohydrates, fats, and proteins without an adequate caloric intake will lead to starvation and cannibalism of the body's own tissue for energy.
4-16. Plant foods provide carbohydrates—the main source of energy. Many plants provide enough protein to keep the body at normal efficiency. Although plants may not provide a balanced diet, they will sustain you even in the arctic, where meat's heat-producing qualities are normally essential. Many plant foods such as nuts and seeds will give you enough protein and oils for normal efficiency. Roots, green vegetables, and plant foods containing natural sugar will provide calories and carbohydrates that give the body natural energy.
4-17. The food value of plants becomes more and more important if you are eluding the enemy or if you are in an area where wildlife is scarce. For instance—
You can dry plants by wind, air, sun, or fire. This retards spoilage so that you can store or carry the plant food with you to use when needed.
You can obtain plants more easily and more quietly than meat. This is extremely important when the enemy is near.
4-18. Meat is more nourishing than plant food. In fact, it may even be more readily available in some places. However, to get meat, you need to know the habits of and how to capture the various wildlife.
4-19. To satisfy your immediate food needs, first seek the more abundant and more easily obtained wildlife, such as insects, crustaceans, mollusks, fish, and reptiles. These can satisfy your immediate hunger while you are preparing traps and snares for larger game.
4-20. In any situation, cleanliness is an important factor in preventing infection and disease. It becomes even more important in a survival situation. Poor hygiene can reduce your chances of survival.
4-21. A daily shower with hot water and soap is ideal, but you can stay clean without this luxury. Use a cloth and soapy water to wash yourself. Pay special attention to the feet, armpits, crotch, hands, and hair as these are prime areas for infestation and infection. If water is scarce, take an "air" bath. Remove as much of your clothing as practical and expose your body to the sun and air for at least 1 hour. Be careful not to sunburn.
4-22. If you don't have soap, use ashes or sand, or make soap from animal fat and wood ashes if your situation allows. To make soap—
Extract grease from animal fat by cutting the fat into small pieces and cooking it in a pot.
Add enough water to the pot to keep the fat from sticking as it cooks.
Cook the fat slowly, stirring frequently.
After the fat is rendered, pour the grease into a container to harden.
Place ashes in a container with a spout near the bottom.
Pour water over the ashes and collect the liquid that drips out of the spout in a separate container. This liquid is the potash or lye.
4-23. Another way to get the lye is to pour the slurry (the mixture of ashes and water) through a straining cloth.
In a cooking pot, mix two parts grease to one part lye.
Place this mixture over a fire and boil it until it thickens.
After the mixture (the soap) cools, you can use it in the semiliquid state directly from the pot. You can also pour it into a pan, allow it to harden, and cut it into bars for later use.
Keep Your Hands Clean
4-24. Germs on your hands can infect food and wounds. Wash your hands after handling any material that is likely to carry germs, after urinating or defecating, after caring for the sick, and before handling any food, food utensils, or drinking water. Keep your fingernails closely trimmed and clean, and keep your fingers out of your mouth.
Keep Your Hair Clean
4-25. Your hair can become a haven for bacteria or fleas, lice, and other parasites. Keeping your hair clean, combed, and trimmed helps you avoid this danger.
Keep Your Clothing Clean
4-26. Keep your clothing and bedding as clean as possible to reduce the chances of skin infection or parasitic infestation. Clean your outer clothing whenever it becomes soiled. Wear clean underclothing and socks each day. If water is scarce, "air" clean your clothing by shaking, airing, and sunning it for 2 hours. If you are using a sleeping bag, turn it inside out after each use, fluff it, and air it.
Keep Your Teeth Clean
4-27. Thoroughly clean your mouth and teeth with a toothbrush at least once each day. If you don't have a toothbrush, make a chewing stick. Find a twig about 20 centimeters (cm) (8 inches) long and 1 centimeter (1/3 inch) wide. Chew one end of the stick to separate the fibers. Then brush your teeth thoroughly. Another way is to wrap a clean strip of cloth around your fingers and rub your teeth with it to wipe away food particles. You can also brush your teeth with small amounts of sand, baking soda, salt, or soap. Rinse your mouth with water, salt water, or willow bark tea. Also, flossing your teeth with string or fiber helps oral hygiene.
4-28. If you have cavities, you can make temporary fillings by placing candle wax, tobacco, hot pepper, toothpaste or powder, or portions of a gingerroot into the cavity. Make sure you clean the cavity by rinsing or picking the particles out of the cavity before placing a filling in the cavity.
Take Care of Your Feet
4-29. To prevent serious foot problems, break in your shoes before wearing them on any mission. Wash and massage your feet daily. Trim your toenails straight across. Wear an insole and the proper size of dry socks. Powder and check your feet daily for blisters.
4-30. If you get a small blister, do not open it. An intact blister is safe from infection. Apply a padding material around the blister to relieve pressure and reduce friction. If the blister bursts, treat it as an open wound. Clean and dress it daily and pad around it. Leave large blisters intact. To avoid having the blister burst or tear under pressure and cause a painful and open sore, do the following:
Obtain a sewing-type needle and a clean or sterilized thread.
Run the needle and thread through the blister after cleaning the blister.
Detach the needle and leave both ends of the thread hanging out of the blister. The thread will absorb the liquid inside. This reduces the size of the hole and ensures that the hole does not close up.
Pad around the blister.
Get Sufficient Rest
4-31. You need a certain amount of rest to keep going. Plan for regular rest periods of at least 10 minutes per hour during your daily activities. Learn to make yourself comfortable under less-than-ideal conditions. A change from mental to physical activity or vice versa can be refreshing when time or situation does not permit total relaxation.
Keep Campsite Clean
4-32. Do not soil the ground in the campsite area with urine or feces. Use latrines, if available. When latrines are not available, dig "cat holes" and cover the waste. Collect drinking water upstream from the campsite. Purify all water.