Water water everywhere

Water is pretty neat stuff.  Just like every other substance which we depend on for life- oxygen, nutrients and vitamins, day time talk shows- water in the proper amount keeps us going while a small adjustment in either direction disrupts our precarious balance between life and death.  Too much water and, well you drown, or assuming you are not swimming at the time, too much water can cause havoc with the electrolyte balance in our body causing the sometimes fatal condition know as hyponatremia.  Of course too much water is generally not a concern, at home or on trail, but too little water is an ailment that most people suffer from to varying degrees.

The cold statistics:

Humans are roughly 60% water depending on age, sex and physical condition.

So for a man of my size, 175 pounds or so-

175 x .6 (percentage of that weight which is water)= 105 pounds of water

105 lbs of water / 8.3 (roughly the weight of a gallon of water)= 13 gallons of water in me

13 gallons x 3.7 (3.78 liters per gallon)=46 liters of water 

Now of course this does not mean I have 46 liters of water in my body, it just gives you an approximate idea of how much water you'll need to replace every day, so lets go on into eqautionland:

We on average lose about 5% of our water every day, which is why folks say "drink 2 liters of water a day."  The problem with blanket amounts is that they don't take into consideration how hard you are working (sweating) how cold/hot and dry the air is, how big you are and so on.  So if we go by the 5% rule:

5% of 46=2.3 liter per day (.6 gallons) for me but...

When I am pulling a loaded sled and working hard and breathing in cold dry air while exhaling warm moist air I can bump up that fluid loss to 8%, 10% even 15%, which means in the winter I need to drink:

10% of 46 = 4.6 liter a day (.9 gallons)

15% of 46= 6.9 liter a day  (1.7 gallons)

A sure sign of fluid loss- The Beardcicle  

At a 1% or 2% fluid loss you feel thirsty, which means you are dehydrated, but don't worry, most people are at this stage and correcting this problem is as simple as drinking a glass of water.  

Around the 5% level you start to feel the first signs of real dehydration- headache, muscle cramps, lethargy

10% and you are starting to go downhill fast- your urine is dark and smelly, your vision can be impaired, your pulse goes way up and if you don't drink some water you will start circling the drain

At the 15% fluid loss consciousness becomes a distant memory and you need medical care.  

Even at low level dehydration, your body will stop functioning the way it likes to.   A loss of water reduces the viscosity and amount of the blood in your body which disrupts your body's ability to thermoregulate effectively, you are more prone to injury and your higher level brain functions are impaired.  All of which are not good for your long term health at home and especially on trail in the winter. So if you are feeling thirsty, your pee pee is yellow and has an odor, and/or you are getting a bit crabby, drink some water, keep the caffeine to a minimum, and reduce your work load to keep the fluid loss under control.  

Oh yeah, as I am sure this will be asked, you can indeed eat snow.  The problem with eating snow is the temperature of the snow, or more specifically the temperature difference between the snow and your body.  You get water into your body by eating snow, but it takes energy to melt and warm the snow so if you are already cold or running a bad calorie deficit, eating snow may not be the best choice.  I have read that melting the snow in your mouth alleviates some of that problem, and as someone who eats snow all the time in the winter (Hey I am allowed to forget my water bottle once in a while) I have found it better to kinda roll the snow around your mouth until the snow is melted, then drink it down as a liquid.  Of course, make sure the snow is clean...