question: how much water should one really drink in a day? Every source recommends a different amount. How do the electrolytes work?
comment: Electrolytes are just a fancy way of saying salt, and other minerals dissolved in water. Pure water doesn't conduct electricity very well. Once you put salt in it, it conducts electricity much better. One part of your body that relies on this very heavily is your nerves. Nerves work by sending little electrical signals all over your body, and if you don't have the right balance of electrolytes in your body, it can cause problems. You sometimes hear about this in long distance runners. Your sweat has salt in it. If you sweat a bunch, then drink water, you are losing electrolytes in your sweat, but not replacing them in the water you're drinking. If you run for a very long time, like a marathon, you can sweat enough to cause an electrolyte imbalance. That's why sports drinks like Gatorade have salt in them, to replace the salt lost when sweating.
passages: For healthful hydration, the current EFSA guidelines recommend total water intakes of 2.0 L/day for adult females and 2.5 L/day for adult males. These reference values include water from drinking water, other beverages, and from food. About 80% of our daily water requirement comes from the beverages we drink, with the remaining 20% coming from food. Water content varies depending on the type of food consumed, with fruit and vegetables containing more than cereals, for example. These values are estimated using country-specific food balance sheets published by the Food and Agriculture Organisation of the United Nations.
   Measurement of electrolytes is a commonly performed diagnostic procedure, performed via blood testing with ion-selective electrodes or urinalysis by medical technologists. The interpretation of these values is somewhat meaningless without analysis of the clinical history and is often impossible without parallel measurements of renal function. The electrolytes measured most often are sodium and potassium. Chloride levels are rarely measured except for arterial blood gas interpretations, since they are inherently linked to sodium levels. One important test conducted on urine is the specific gravity test to determine the occurrence of an electrolyte imbalance.
  
  Section::::Physiological importance.:Rehydration.
   Early recommendations for the quantity of water required for maintenance of good health suggested that 6–8 glasses of water daily is the minimum to maintain proper hydration. However the notion that a person should consume eight glasses of water per day cannot be traced to a credible scientific source. The original water intake recommendation in 1945 by the Food and Nutrition Board of the National Research Council read: "An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods." More recent comparisons of well-known recommendations on fluid intake have revealed large discrepancies in the volumes of water we need to consume for good health. Therefore, to help standardize guidelines, recommendations for water consumption are included in two recent European Food Safety Authority (EFSA) documents (2010): (i) Food-based dietary guidelines and (ii) Dietary reference values for water or adequate daily intakes (ADI). These specifications were provided by calculating adequate intakes from measured intakes in populations of individuals with “desirable osmolarity values of urine and desirable water volumes per energy unit consumed.”
   The human body contains from 55% to 78% water, depending on body size. To function properly, the body requires between of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors. Most of this is ingested through foods or beverages other than drinking straight water. It is not clear how much water intake is needed by healthy people, though the British Dietetic Association advises that 2.5 liters of total water daily is the minimum to maintain proper hydration, including 1.8 liters (6 to 7 glasses) obtained directly from beverages. Medical literature favors a lower consumption, typically 1 liter of water for an average male, excluding extra requirements due to fluid loss from exercise or warm weather.
   Urine osmolality
  
  Urine osmolality is a measure of urine concentration, in which large values indicate concentrated urine and small values indicate diluted urine. Consumption of water (including water contained in food) affects the osmolality of urine.
  
  In healthy humans with restricted fluid intake, urine osmolality should be greater than 800 mOsm/kg, while a 24-hour urine osmolality should average between 500 and 800 mOsm/kg.
   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 (RDI) for water is 3.7 litres 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 litres (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 daily intake of water is required for the normal physiological functioning of the human body. The USDA recommends a daily intake of "total water": not necessarily by drinking but by consumption of water contained in other beverages and foods. The recommended intake is 3.7 liters (appx. 1 gallon) per day for an adult male, and 2.7 liters (appx. 0.75 gallon) for an adult female. Other sources, however, claim that a high intake of fresh drinking water, separate and distinct from other sources of moisture, is necessary for good health – eight servings per day of eight fluid ounces (1.8 liters, or 0.5 gallon) is the amount recommended by many nutritionists, although there is no scientific evidence supporting this recommendation.
   WHO states that knowing the levels of serum electrolytes rarely changes the recommended treatment of children with diarrhea and dehydration, and furthermore, that these values are often misinterpreted. Most electrolyte imbalances are adequately treated by ORS. For example, a child who has been given an excess of sugar or salt like that which is in commercial soft drinks, sugared fruit drinks, or over-concentrated infant formula, may develop hypernatraemic dehydration. This occurs when these over-concentrated solutions sit in the gut and draw water from the rest of the body, and the reduced fluids in the body's tissues then have a higher proportion of salt to fluid. Children with serum sodium greater 150 mmol/liter have thirst out of proportion to other signs of dehydration. There is a danger of convulsions which usually occur when serum sodium concentrations are greater than 165 mmol/liter. Less commonly, convulsions can also occur when serum sodium is less than 130 mmol/liter. Treatment with ORS can usually bring serum sodium concentrations back to normal within twenty-four hours.
   In the United States, the reference daily intake (RDI) for total water is per day for human males older than 18, and per day for human females older than 18 which includes drinking water, water in beverages, and water contained in food. An individual's thirst provides a better guide for how much water they require rather than a specific, fixed quantity. Americans, on average, drink of water a day and 95% drink less than per day.
   Sodium deficit = (140 – serum sodium) x total body water
  
  Total body water = kilograms of body weight x 0.6  
  
  Section::::Treatment.:Fluids.
  
  Options include:
  
  BULLET::::- Mild and asymptomatic hyponatremia is treated with adequate solute intake (including salt and protein) and fluid restriction starting at 500 ml per day of water with adjustments based on serum sodium levels. Long-term fluid restriction of 1,200–1,800 mL/day may maintain the person in a symptom free state.
   In healthy people, the drinking of extra water produces mild diuresis to maintain the body water balance. Many people with health problems such as heart failure and kidney failure need diuretic medications to help their kidneys deal with the fluid overload of edema. These drugs help the body rid itself of extra water via the extra urine. The concentrations of electrolytes in the blood are closely linked to fluid balance, so any action or problem involving fluid intake or output (such as polydipsia, polyuria, diarrhea, heat exhaustion, starting or changing doses of diuretics, and others) can require management of electrolytes, whether through self-care in mild cases or with help from health professionals in moderate or severe cases.
   Hydration
  
  Hydration may refer to:
  
  BULLET::::- Hydrate, a substance that contains water
  
  BULLET::::- Hydration enthalpy, energy released through hydrating a substance
  
  BULLET::::- Hydration reaction, a chemical addition reaction where a hydroxyl group and proton are added to a compound
  
  BULLET::::- Hydration shell, a type of solvation shell
  
  BULLET::::- Hydration system, an apparatus that helps its user drink enough liquid while engaged in physical activity
  
  BULLET::::- Hydration pack, a type of hydration system composed of a carry-on pack used for hydration
  
  BULLET::::- Mineral hydration, an inorganic chemical reaction where water is added to the crystal structure of a mineral
   Section::::Background.
   The volume of the reservoir and the pack carrying it can vary widely depending on the purpose of the hydration pack. Some packs are extremely small and minimalist, designed to add as little weight as possible and remain secure while running or cycling, while others are more suited for backpacking and extended hikes, equipped with much larger bladders. However, as water weighs 1kg/l (approx. 8.3 lbs/gal), it is impractical to carry more than a few liters in most situations; typical reservoirs are between 1-3 l even for very large backpacks.
   The adult male body is about 60% water for a total water content of some 42 litres. This is made up of about 19 litres of extracellular fluid including about 3.2 litres of blood plasma and about 8.4 litres of interstitial fluid, and about 23 litres of fluid inside cells. The content, acidity and composition of the water inside and outside cells is carefully maintained. The main electrolytes in body water outside cells are sodium and chloride, whereas within cells it is potassium and other phosphates.
  
  Section::::Composition.:Cells.
   The amount of drinking water required is variable. It depends on physical activity, age, health, and environmental conditions. In a temperate climate under normal conditions, adequate water intake is about for adult women and for adult men. Physical exercise and heat exposure cause loss of water and therefore may induce thirst and greater water intake. Physically active individuals in hot climates may have total daily water needs of or more. The European Food Safety Authority recommends per day for adult women and per day for adult men.
   Fluid intake should be adjusted individually as factors such as body weight, sex, climate, pace, fitness (VO max), and sweat rate are just a few variables that change fluid requirements between people and races. The International Marathon Medical Directors Association (IMMDA) advises that runners drink a sports drink that includes carbohydrates and electrolytes instead of plain water and that runners should "drink to thirst" instead of feeling compelled to drink at every fluid station. Heat exposure leads to diminished thirst drive and thirst may not be a sufficient incentive to drink in many situations. The IMMDA and HSL Harpur Hill give recommendations to drink fluid in small volumes frequently at an approximate rate falling between every 15 minutes. A patient suffering hyponatremia can be given a small volume of a concentrated salt solution intravenously to raise sodium concentrations in the blood. Some runners weigh themselves before running and write the results on their bibs. If anything goes wrong, first aid workers can use the weight information to tell if the patient had consumed too much water.
   Electrolyte balance is maintained by oral, or in emergencies, intravenous (IV) intake of electrolyte-containing substances, and is regulated by hormones, in general with the kidneys flushing out excess levels. In humans, electrolyte homeostasis is regulated by hormones such as antidiuretic hormones, aldosterone and parathyroid hormones. Serious electrolyte disturbances, such as dehydration and overhydration, may lead to cardiac and neurological complications and, unless they are rapidly resolved, will result in a medical emergency.
  
  Section::::Physiological importance.:Measurement.
   Malnourished children have an excess of body sodium. Recommendations for home remedies agree with one liter of water (34 oz.) and 6 teaspoons sugar and disagree regarding whether it is then one teaspoon of salt added or only 1/2, with perhaps most sources recommending 1/2 teaspoon of added salt to one liter water.
  
  Section::::Treatment.:Low blood sugar.
   Electrolytes are important because they are what cells (especially nerve, heart and muscle cells) use to maintain voltages across their cell membranes and to carry electrical impulses (nerve impulses, muscle contractions) across themselves and to other cells. Kidneys work to keep the electrolyte concentrations in blood constant despite changes in the body. For example, during heavy exercise, electrolytes are lost in sweat, particularly in the form of sodium and potassium. These electrolytes must be replaced to keep the electrolyte concentrations of the body fluids constant.
  
  Section::::See also.
  
  BULLET::::- Acidosis
  
  BULLET::::- Alkalosis
  
  BULLET::::- Dehydration
  
  BULLET::::- Malnutrition
  
  BULLET::::- Starvation
  
  BULLET::::- Sports drink
   The management of dehydration typically involves the use of oral rehydration solution (ORS). Standard home solutions such as salted rice water, salted yogurt drinks, vegetable and chicken soups with salt can be given. Home solutions such as water in which cereal has been cooked, unsalted soup, green coconut water, weak tea (unsweetened), and unsweetened fresh fruit juices can have from half a teaspoon to full teaspoon of salt (from one-and-a-half to three grams) added per liter. Clean plain water can also be one of several fluids given. There are commercial solutions such as Pedialyte, and relief agencies such as UNICEF widely distribute packets of salts and sugar. The World Health Organization (WHO) describes a homemade ORS with one liter water with one teaspoon salt (or 3 grams) and six teaspoons sugar (or 18 grams) added (approximately the “taste of tears”). The WHO; however, does not generally recommend homemade solutions as how to make them is easily forgotten. Rehydration Project recommends adding the same amount of sugar but only one-half a teaspoon of salt, stating that this more dilute approach is less risky with very little loss of effectiveness. Both agree that drinks with too much sugar or salt can make dehydration worse.
   The approximate amount of oral rehydration solution (ORS) to be given over four hours can be obtained by multiplying 75 milliliters of solution by the child’s weight in kilograms. For example, a child who weighs 15 kilograms should be given approximately 1,125 ml of ORS over four hours. Of course, the exact amount depends on how dehydrated the child is. And in general, let the person drink as much as they wish. The person can drink a little faster at first and then relatively slowly. For babies, a dropper or syringe without the needle may be used. Toddlers under two should be offered a teaspoonful every 1–2 minutes. Older children and adults may take frequent sips.
   For routine activities, thirst is normally an adequate guide to maintain proper hydration. Minimum water intake will vary individually depending on weight, environment, diet and genetics. With exercise, exposure to hot environments, or a decreased thirst response, additional water may be required. In athletes in competition drinking to thirst optimizes performance and safety, despite weight loss, and as of 2010, there was no scientific study showing that it is beneficial to stay ahead of thirst and maintain weight during exercise.
   In malnourished persons, rehydration should be performed relatively slowly by drinking or by nasogastric tube unless the person is also suffering from shock in which case it should be performed quicker. Malnourished patients should receive a modified ORS which has less sodium, more potassium, and modestly more sugar. For patients not malnourished, rehydration should be performed relatively rapidly by means of intravenous (IV) solution. For infants under one year of age, WHO recommends giving, within the first hour, 30 milliliters of Ringer’s Lactate Solution for each kilogram of body weight, and then, within the next five hours, 70 milliliters of Ringer’s Lactate per kilogram of body weight. For children over one year and for adults, WHO recommends, within the first half hour, 30 milliliters of Ringer’s Lactate per kilogram of body weight, and then, within the next two-and-a-half hours, 70 milliliters per kilogram. For example, if a child weighs fifteen kilograms (who is obviously over one year of age), he or she should receive 450 ml of Ringer's Lactate Solution within the first half hour, and then 1,050 ml of Ringer's Lactate within the next two-and-a-half hours. Patients who can drink, even poorly, should be given Oral Rehydration Solution (ORS) by mouth until the IV drip is running. In addition, all patients should start to receive some ORS when they are able to drink without difficulty, which is usually three to four hours for infants and one to two hours for older persons. ORS provides additional base and potassium which may not be adequately supplied by IV fluid. Ideally, patients should be reassessed every fifteen to thirty minutes until a strong radial pulse is present, and thereafter, assessed at least hourly to confirm that hydration is improving. Hopefully, patients will graduate to the medium dehydration or "some" dehydration category and receive continued treatment as above.
   Appropriate amounts of supplemental zinc and potassium should be added if available. But the availability of these should not delay rehydration. As WHO points out, the most important thing is to begin preventing dehydration as early as possible. In another example of prompt ORS hopefully preventing dehydration, CDC recommends for the treatment of cholera continuing to give Oral Rehydration Solution during travel to medical treatment.
  