Drinking water / hydration

[The Dark]

This seems pretty good. I've read research that water consumption should be around 1 milliliter per kilocalorie, which is the same as 1 liter per 1000 calories. However, people eating wild or civilized food (or modern MREs that don't rely on freeze-drying) should be able to get about 20% of normal water needs from the food they're eating, so about half a liter to a liter of water can be gained from a day's rations.

For exertion, I think I'd tie it in to the four-hour periods, so that each period of Easy Work adds x0.125 and each period of Hard Work adds x0.25, starting from a typical base of 4L (based on 3 MREs being 1.5 kilograms and ~3750 kilocalories) AND apply the amount after accounting for weather/altitude (i.e. in Hot, Arid weather, the x0.25 applies to the doubled base, rather than being added to the x2 multiplier).

This would mean that in Europe, each four-hour period spent marching would require an extra 1L of water that day, while time spent foraging would require an extra 0.5L per period. Marching for 12 hours would require a total of 7L of water (4L base and 3L for three periods of hard work). In Iraq, the base would be 8L, and you'd need an extra 2L per period spent marching. The exact numbers may need tweaking, but safe water should be a concern.

[swaghauler]

Water is a MAJOR plot point in my Africa MERC campaign. It is a focal point for conflict and generally in short supply (just like in real life).

[CDAT]

One thing to keep in mine with water through the stomach the human body can only absorb about one to one and a half quarts of water an hour. Any more than this and you just pee it out and also run the risk of water intoxication.

[WallShadow]

Originally Posted by CDAT

One thing to keep in mine with water through the stomach the human body can only absorb about one to one and a half quarts of water an hour. Any more than this and you just pee it out and also run the risk of water intoxication.

Which is why one should not be allowed to guzzle a tummyful of water, but swish each sip/mouthful around to allow the mucous membranes to get their share. It is also more psychologically satisfying than gulping, despite the tendency of a desperately thirsty person to do so.
Another issue that makes a stomachful of water counterproductive is the possibility of vomiting up the excess, thereby wasting the water and further dehydrating yourself. At least peeing it out keeps one's kidneys in function and staves off damaging them.

[The Dark]

Originally Posted by The Dark

For exertion, I think I'd tie it in to the four-hour periods, so that each period of Easy Work adds x0.125 and each period of Hard Work adds x0.25, starting from a typical base of 4L (based on 3 MREs being 1.5 kilograms and ~3750 kilocalories) AND apply the amount after accounting for weather/altitude (i.e. in Hot, Arid weather, the x0.25 applies to the doubled base, rather than being added to the x2 multiplier).

This would mean that in Europe, each four-hour period spent marching would require an extra 1L of water that day, while time spent foraging would require an extra 0.5L per period. Marching for 12 hours would require a total of 7L of water (4L base and 3L for three periods of hard work). In Iraq, the base would be 8L, and you'd need an extra 2L per period spent marching. The exact numbers may need tweaking, but safe water should be a concern.

After reading an Army Study Guide, the desert amount may actually be an under-estimate, since they recommended 2 quarts (roughly 1.9 liters) per hour of hard work, where I only suggested 2 liters per period (4 hours). They also recommend 2 gallons (~7.6 liters) per 20 miles marched during the day, which would take 2 periods, so ~4 liters per period marching. However, their numbers also appear to be total (i.e. there is no base amount being added to, just an amount to replace losses from exertion), so it's a bit of an apples-to-oranges comparison.

[swaghauler]

I kind of like your water per period idea. Combining it with exertion makes good sense too. I think that rather than adding water for altitude or very low humidity (desert or cold weather), that these should be modifiers towards a CON check IF you aren't getting enough water.

A sample chart might look like this:

Temp 101F+
= 4 Liters per Period of Hard Work.
= 3 Liters per Period of Light Work.
= 1.5 Liters per Period of Rest.

Temp 76F to 100F
= 3 Liters per Period of Hard Work.
= 2 Liters per Period of Light Work.
= 1 Liters per Period of Rest.

Temp 25F to 75F
= 2 Liters per Period of Hard Work.
= 1 Liter per Period of Light Work.
= 0 Liters per Period of Rest.

Temp 24F or Less
= 2 Liters per Period of Hard Work.
= 1 Liters per Period of Light Work.
= 0.5 Liters per Period of Rest.


This would be my first take on Water Consumption per Period.