Bill M Campbell MD FAWM DiMM
As mountain rescuers, we get very focused on finding and rescuing individuals in austere conditions. Some teams even have the motto “So others may live.” But we must constantly remind ourselves of our priorities: self > team > subject. If we don’t take care of ourselves, then we let our
team and possibly the subject down. There are many factors included in taking care of yourself that we will address over time, but in this article we will address water and hydration in the field and afterwards. Hydration is 1 of the 10 essentials of outdoor travel.
We have all been on searches where volunteers with
the right heart come out to help. However, they are usually ill prepared and, at most, carrying 12 ounces of extra water and little else. How much water you need to carry with you depends on your mission and location. On a mission in the East where water is prevalent, a couple of liters of water might suffice for a day. But if the mission turns into a prolonged field deployment, being able to obtain extra
water is crucial. In places where water is particularly plentiful, some team members may only carry 1 liter but have methods of quick water filtration or purification. WATER
55 to 60 percent of adult human bodies are composed
of water. Loss of water (dehydration) affects our performance, starting with as little as two percent dehydration.
For a 75 kilogram man, that would be one and a half kilogram or about one and a half liters of water loss. This may
seem like a lot, but losses from urine output, sweating and our respiratory system add up quickly. Maintaining normal hydration requires between 1.5 liters and 2.5 liters per day without the added losses from exertion (sweating, breathing harder, heavier muscle activity). The more we lose, the worse our performance. For optimal performance, drinking before starting your activity (prehydration) is recommended. About a half a liter will do and it can be plain water or a sports drink. During activity, frequent sips rather than large quantities taken more infrequently is recommended. Usually 200- 300 milliliters every 20 – 30 minutes will do. This is about half to one liter of water per hour of exercise. If you are having to take a bioBreak (needing to urinate) every one to two hours, you are probably keeping up with your water losses. For very short duration activities (90 minutes or less), plain water will suffice. Anything longer than that, drinking a combination of plain water with some sports drink mixture will work better (carrying powders that you can mix yourself on the trail works well). Post exercise rehydration is most optimal within one to two hours after stopping exercise. This includes electrolyte replacement along with carbohydrates and lean protein. How much water you need to carry depends on many factors. Personal factors (some people’s bodies are more efficient and lose less water), activity levels, and environmental conditions (in heat you will need more water as the body sweats even more trying to cool yourself off) are important variables. Whether you can replenish water while out in the field and whether you need to carry additional water for your subjects are other important factors. I would say that most team members should carry 1-2 liters into the field. Options for carrying water are generally either a separate container (Nalgene bottle, metal bottle) or a hydration pack. How you carry is somewhat a personal preference. Hydration packs allow you to
sip as you go with less effort to access water. Bottles are more durable and some even come with filtration/ purification built in. I find that for activities where I wear my pack most of the time (searching) the hydration pack serves well. But if I am working with my pack set off to the side, then a bottle seems easier to use. Hydration bladders should be cleaned out routinely.
Bottles are easier to use if you want to mix up a rehydration drink in the field. It is important that you do not use and reuse a purchased bottle of water. These add to the growing problem of plastic waste and they are not BPAfree. Most bottles you can buy now to carry water are BPA, BPS and phthalate-free.
REPLENISHING WATER IN FIELD
How much water you need to carry is very dependent on access to water in the field. Even if you have access to fresh water, you must consider how to create safe drinking water. It is not a question of whether water is contaminated but how much it is contaminated. All water in the
field will contain some combination of bacteria, viruses, protozoa, chemicals, heavy metals, and micro plastics.
All of these can have a profound effect on your health. Some effects are fairly quick microorganisms) and some effects are more long-term and insidious (chemicals, heavy metals, micro plastics). The old- fashioned method of boiling water still works (at least for most microorganisms) but requires time, a vessel to heat water in and a heat source.
Easier methods are filtration and purification. Filtration usually clears bacteria and protozoans and micro plastics.
Purification also clears viruses and chemicals and heavy metals. With most water sources in North America, filtration will suffice. But if you go into a disaster area (e.g., hurricane, flooding) this might not hold true. There are numerous evaluations of purification and filtration devices online. Look them over and decide what system works best for you. Other methods such as chlorine dioxide tablets
or drops can also work but you need to wait 30 minutes to 4 hours for them to reach effectiveness. The best idea is to carry 2 types of treatment in case one breaks. Two is one, one is none.
STRAIGHT WATER OR ELECTROLYTE REPLACEMENT?
If your activity is less than 90 minutes, straight water will suffice, especially if you also rehydrate and eat right after the exercise. Longer activities will require more attention to electrolyte replacements (and also carbohydrates).
Electrolyte replacement can be achieved with salty snacks in addition to water. A more complete replacement would be one of the rehydration solutions. Premixed is not as efficient as a powder mix you can carry. Some powders even come with a sugar free option. Be careful about hydrating with lots of straight water (and not eating, especially something with salt in it) because you can cause hyponatremia (low sodium). This can be serious, especially in the field as performance and decision making can suffer drastically. TAKE HOME POINTS: 1. Prehydrate 2. Hydrate often while exercising 3. Hydrate more at altitude (lower humidity so more insensible losses) 4. Don’t forget to hydrate when it is cold 5. Treat any water replenishment in field with suspicion 6. Don’t over-hydrate with straight water 7. Don’t forget to rehydrate immediately after you finish your activity
