Dehydration

Dehydration is the consequence of not drinking enough water, which must be replenished every day, particularly in hot, dry weather. The amount of water that must be drunk to remain healthy is determined by the character's weight, adjusted by the day's peak temperature grade. This water need not be pure, though even mildly impure water may have unpleasant results.

In most northerly climates, dehydration is a comparatively minor concern; temperate and sub-arctic environments abound in fresh water, while humanoids need comparatively little water to maintain themselves. In hot climates, however, the lack of a fresh supply of water can quickly become dire, leading to shocking effects on the body and an unpleasant death.

Water requirements per day, by temperature

temperature grade	fl.oz./lb. of weight, per day
pleasant and below	0.5
warm, balmy or sweaty	0.6
sweltering to feverish	0.7
baking	0.9
scorching	1.2

For those unfamiliar with fluid ounces, there are 16 fl.oz. in a pint, 32 fl.oz. in a quart, 128 fl.oz. in a gallon and 33.8 fl.oz. in a litre.

Water Requirements

The table indicates the amount of water that a character needs, depending upon his or her weight and the relative temperature. A 100-lb. character, for example, in pleasant conditions (up to 69°F/21°C), would need to drink about 50 fluid ounces of water to remain hydrated, which is a little more than 1½ quarts. In warm, balmy, or sweaty conditions (between 70-99°F/22-37°C), that same character would need to drink 60 fluid ounces each day, nearly two quarts.

A goatskin bag or a winesack, used to carry fluid, each has a capacity of two quarts, showing that characters must find a source of water nearly every day when travelling. Common sources of water that even outsiders may access include natural springs, rivers, streams and wells, as well as rainwater collected in cisterns or barrels. Thus, every thorp or hamlet becomes an important place for characters to stop at.

It's beneficial if a party carries along a keg, which has a capacity of five gallons, for extended travel to places where there might not be an immediate water source. This, of course, requires a donkey or other pack animal, as a full keg weighs more than 33 lbs. Additionally, it's advisable to have other portable containers that can be easily carried and refilled, ensuring a constant supply of water for hydration needs.

Food as Water

For simplicity, one pound of food can also be judged to be 8 fl.oz. of water for the sake of hydration.

If there's a reason to note the difference between one food and another, the following numbers can be used as an alternative: fruits and vegetables, 80-92% water; meat, 60-75% water; breads, 35-40% water; grains and dry foods, like rice, 10% water.

Water Loss & Health

Typically, the body loses water through respiration, perspiration, urination, defecation and general diffusion through the skin. This combined loss determines the amount of water characters must consume each day. However, there are other factors that can increase water loss: the most concerning are increased perspiration due to disease, diarrhea and vomiting. In each of these cases, the individual must drink more water to compensate for the additional loss.

For game purposes, we may describe any one of these as a 20% increase in the amount of fluid that needs to be drunk that day. While not always true, rather than attempting to specify which diseases produce this requirement and which do not, it's best if we assume that the contraction of any disease increases the body's demands for fluid, regardless of severity, with any additional increase being specified within the description of the disease itself.

Diarrhea and vomiting also may occur with the onset of a disease, and should be treated as a separate +20% water intake when they do. Both may also occur as a quantifiable effect of eating, from poorly prepared grub, chow, nosh or even occasionally savoury foods. When this occurs, the DM should note an increase in water requirements that day.

Surviving on Less Water

The need for water is a notoriously inflexible demand on the body, but for short periods it's possible to reduce one's water intake by any amount up to 10%, though symptoms of thirst, dry mouth, darker urine and decreased urine output are liable to begin within just 2 to 3 days. If water intake isn't increased again within 6 days, the character experiences fatigue, headaches and dizziness that amounts to a -2 drop to all their ability stats, as well as an addition -2 to the character's attack rolls or saving throws.

Reducing one's water intake by 11 to 15% produces these symptoms within 36 hours, while a reduction between 15 and 20% will be felt within 2 to 3 hours. Any further reduction will be felt immediately. Each day thereafter causes an additional -2 to the character's attributes, to hit and saving throws, continuing until any stat reaches zero, whereupon the character dies. If intelligence drops below 6, the character ceases to think intelligently, so that he or she will stumble off in a direction randomly, perhaps chancing to encounter water but more probably not. These characters may be managed somewhat by others who have retained their senses, but without a water source, this becomes harder and harder, until everyone is reduced to incompetence.

See also,
Barkskin (spell)
Desert (range)
Dowse for Water (sage ability)
Foraging (sage ability)
Identify Clean Water (sage ability)
The Adventure
Travel
Water Discipline (sage ability)