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People need a certain amount of water per day, in order to survive. Some people recommend the "8 glasses of 8 oz water".

Other people go about calculating the average loss of water per day and try to find a way to replace it. This is roughly 2-3 liters of water, given that urine is about 1.5 liters,

The average urine output for adults is about 1.5 liters (6.3 cups) a day. You lose close to an additional liter (about 4 cups) of water a day through breathing, sweating and bowel movements. Food usually accounts for 20 percent of your total fluid intake, so if you consume 2 liters of water or other beverages a day (a little more than 8 cups) along with your normal diet, you will typically replace your lost fluids.

The Institute of Medicine advises that men consume roughly 3 liters (about 13 cups) of total beverages a day and women consume 2.2 liters (about 9 cups) of total beverages a day.





Whatever the case, people need at least 64 oz of water a day, and probably, well over 75.

A gallon of water weighs roughly 8.35 lb. A liter of water is, by definition, 1 kilogram per liter, or 2.2 lb.

A person in combat is advised to drink roughly 100-120z of water per day, or, 6.5 to 8.3 lb of water per day.

And a person in combat (or heavy physical exercise) is also advised to eat roughly 4200 calories a day.




Even if we take the minimum amount of water necessary per day, or roughly 80 ounces, we get that a person needs 5.21 pounds of water per day. Considering that a person needs roughly 100 ounces of water per day, for a basic 3 day combat patrol the ordinary person needs roughly 19.5 lb of water.

If we calculate in the weight of a weapon (7.5lb-10lb) plus the weight of 330 rounds of ammunition and magazines (roughly 11-15lb), that alone is 38-44.5 lb's of gear alone. If we mix in the weight of a pair of boots (3-5lb) a standard BDU, a backpack, container for water, MRE's for three days (650 grams each, so roughly 4lb), a knife, a map, a radio, some basic utensils, and a tactical vest, we get, at least, another 10-15 lb.

That alone is 50-60 lb's of gear. If we mix in the weight of body armor, this is roughly 60-75 lb's of gear. If we consider the fact a person may be carrying a machine gun, extra ammunition, grenades, and other stuff, it is conceivable that a person may be carrying over 75 pounds of gear.

Considering all this weight, and all the water necessary to sustain this weight in a combat situation, for just three days we have a nearly 20 pound water requirement, if not more.




Question is, anybody have any ideas of how to lower weight/lower weight of water, or figuring out a way to compensate for the water needed?

Exactly.

So, how do we turn people into camels... herm...

Thinking innovatively, could we not incorporate those navigational things (flashlight, GPS, radio, etc) into a HUD in something of a more compact LandWarrior system? That might not reduce the weight but distribute it more ergonomically as the apparatus can be accessed with minimal movement or effort.

It's a handicap to look for fresh water all the time. Some simple solutions can be:
1) Use your knife wisely. If there are trees of any kind nearby, get choppy and learn to extract water or sap from trunks and get some of your water and calories from that.

2) Ion supplements. Salty stuff helps retain water in the blood cells and reduces water lost in both perspiration and respiration. Not good for prolonged use but for three days it shouldn't be a problem.

3) Don't be squeamish. Your urine is sterile for about half a minute after released. In dire need, drink it quick and deal with the taste. Plus it contains any nutrients you may not have used during the period of digestion.

4) Psychological conditioning. The release of too much adrenaline speeds up respiration and perspiration and is to the detriment of water conservation. Nervous sweating is bad, because it's useless and preventable.

Well considering that there's a primitive way of reusing urine, there should be a pretty cool way to do that with technology.

The way I know of involves taking a piece of plastic wrap, a styrofoam (spelling?) cup, and putting the cup in some sand. I'd list the steps but it seems that I have them mixed up now, and I'm not sure which goes first.

Actually on this subject, life saver bottles can filter almost any source of water, and if you dig down deep enough, just a few feet, in the desert, dirt in a forest, and so on, you'll get water, so since the filter can turn almost any source of water, dirt, contagion, and so on, into clean water, you can go on for a long time.

The life saver filter in particular can filter about 5000 liters of water, or at least 1250 gallons, so that's like, 1 gallon a day, 1250 days, or 3.5 years. O_O