Drinking water / hydration

[The Dark]

Unless I have gone even more blind than usual, while v2.2 includes diseases from contaminated water, it doesn't seem to include rules for water consumption/dehydration. It's certainly not in the Upkeep section (pages 148-150), since I read through that a few times to check. Has anyone come up with water consumption rules, preferably ones that account for exertion and/or temperature?

[swaghauler]

Based on what I learned in my survival training (at ACE Adventure Center WV) and Cold Weather Mountain School (with the 10th Mountain), a soldier needs 1 LITER of water per 1000 Calories they expend per day. This volume of water (about 4L. to 5L. per day on average) is modified by the following situations:

Extreme Hard Work (digging foxholes, marching with a heavy load, etc...) X2
Cold Weather (32F to 0F) X1.25
Extreme Cold Weather (Below 0F) X1.5
Warm Weather, Humid (80F to 100F) X1.25
Warm Weather, Arid (80F to 100F) X1.5
Extreme Warm Weather, Humid (101F+) X1.5
Extreme Warm Weather, Arid (101F+) X2

Elevation above 5000ft adds X0.5 to the above climatic conditions.
Elevation above 10,000ft REQUIRES constant hydration (with the X0.5 add) to avoid HAPE (high altitude pulmonary edema) and HAPE can occur at lower elevations (as low as 8,000ft for the uninitiated). Hydrate or die in these situations.

All of these modifiers add together to create the water intake needed. For my Africa campaign, I just specify that the team needs 5L per day EACH. The native NPCs in my campaign need 4L per day. In a European campaign where the characters were marching, I'd say 3L per day would be appropriate for an average consumption. If you had a campaign in Iraq during the summer, 10L per man would not be unheard of if they were marching with weight during the heat of the day.

If the characters do not get enough water but at least half of the daily requirement, I allow a roll under CON on 1D10 to avoid any ill effects. A failure increases Fatigue by one Level (ie Light becomes Moderate). Drinking LESS than half of the daily requirement results in a 1 Level gain in Fatigue per Period until you hydrate.

I have posted a Water Contamination Table in the Water Purification Thread in the Forum Map. I hope this helps but my data is about 10 years old and the charts above involve worse case scenarios. I know the Army has a study on the internet about hydration as well.

Swag.

[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.