Water consumption The amount of water varies with the individual, as it depends on the condition of the subject, the amount of physical exercise, and on the environmental temperature and humidity. In the US, the Reference Daily Intake reference daily intake (RDI) for water is 3.7 liters per day (L/day) for human males older than 18, and 2.7 L/day for human females older than 18 including water contained in food, beverages, and drinking water. The common misconception that everyone should drink two liters (68 ounces, or about eight 8-oz glasses) of water per day is not supported by scientific research. Various reviews of all the scientific literature on the topic performed in 2002 and 2008 could not find any solid scientific evidence that recommended drinking eight glasses of water per day. For example, people in hotter climates will require greater water intake than those in cooler climates. An individual's thirst provides a better guide for how much water they require rather than a specific, fixed number. A more flexible guideline is that a normal person should urinate 4 times per day, and the urine should be a light yellow color. A constant supply is needed to replenish the<unk> s lost through normal physiological activities, such as respiration, perspiration and urination. Food contributes 0.5 to 1 L/day, and the metabolism of protein, fat, and carbohydrates produces another 0.25 to 0.4 L/day, which means that 2 to 3 L/day of water for men and 1 to 2 L/day of water for women should be consumed as<unk>  to meet the Recommended Daily Intake (RDI). Trace elements In terms of mineral nutrients intake, it is unclear what the drinking water contribution is. However, inorganic minerals generally enter surface water and ground water via storm water runoff or through the Earth's crust. Treatment processes also lead to the presence of some minerals. Examples include calcium, zinc, manganese, phosphate, fluoride and sodium compounds. Water generated from the biochemical metabolism of nutrients provides a significant proportion of the daily water requirements for some arthropods and desert animals, but provides only a small fraction of a human's necessary intake. There are a variety of trace elements present in virtually all potable water, some of which play a role in metabolism. For example, sodium, potassium and chloride are common chemicals found in small amounts in most waters, and these elements play a role in body metabolism. Other elements such as fluoride, while arguably beneficial in low concentrations, can cause dental problems and other issues when present at high levels. Water is essential for the growth and maintenance of our bodies, as it is involved in a number of biological processes. Medical use Effects of illness When a person is ill,<unk>  may also be lost through vomiting, diarrhea, and hemorrhage. An individual is at an increased risk of dehydration in these instances, as the kidneys will find it more difficult to match<unk>  loss by reducing urine output (the kidneys must produce at least some urine in order to excrete metabolic waste.) Oral rehydration therapy Oral rehydration therapy (ORT), is type of<unk>  replacement used as a treatment for dehydration. In an acute hospital setting,<unk>  is monitored carefully. This provides information on the patient's state of hydration, kidney function and cardiovascular function. * If<unk>  loss is greater than<unk>  gain (for example if the patient vomits and has diarrhea), the patient is said to be in negative<unk> . In this case,<unk>  is often given intravenously to compensate for the loss. * On the other hand, a positive<unk>  (where<unk>  gain is greater than<unk>  loss) might suggest a problem with either the kidney or cardiovascular system. If blood pressure is low (hypotension), the filtration rate in the kidneys will lessen, causing less<unk>  reabsorption and thus less urine output. An accurate measure of<unk>  is therefore an important diagnostic tool, and allows for prompt intervention to correct the imbalance.
Fluid balance
Dialysis adequacy
Modes of mechanical ventilation
Hemodialysis product
Blood volume
Rate of infusion
Air filtration in operating rooms
Renal physiology