Drinking is the act of ingesting water or other drinks through the mouth. Water is required for many of life’s physiological processes. Both excessive and inadequate water intake are associated with health problems.
Human drinking 
When a liquid is poured into an open human mouth, the swallowing process is completed by peristalsis which delivers the liquid to the stomach; much of the activity is abetted by gravity. The liquid may be poured from the hands or drinkware may be used as vessels. Drinking can also be performed by acts of inhalation, typically when imbibing hot liquids or drinking from a spoon. Infants employ a method of suction wherein the lips are pressed tight around a source, as in breastfeeding: a combination of breath and tongue movement creates a vacuum which draws in liquid. A human drinking water source is a natural water body (lakes, rivers and groundwater) used to supply a community with drinking water.
A drinking water source standard will: help councils better manage drinking water from the source to the tap provide better information on the suitability of our drinking water sources provide better integration between councils and communities.
Land animals 
Cats, canines, and ruminants all lower the neck and lap in water with their powerful tongues.
Most birds scoop or draw water into the buccal areas of their bills, raising and tilting their heads back to drink (an exception is the common pigeon which can suck in water directly by inhalation).
Cats drink at a slower pace than ruminants, who face greater predation hazards in the wild.
Uniquely, elephants draw water into their trunks and squirt it into their mouths.
Drinking can be observed in many insect species.
The sensation caused by dehydration of the body is called thirst. The sensation of thirst is a dry feeling in the throat coupled with a desire to drink fluids. Thirst is regulated by the hypothalamus in response to subtle changes in the body's electrolyte levels, and also as a result of changes in the volume of blood circulating.
Human water requirements 
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, that is water which is included not only in drinking water itself but all water contained in beverage 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 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 8 fluid ounces (1.8 liters, or 0.5 gallon) is the amount recommended by many nutritionists, although there is no scientific evidence of health benefits for this recommendation.
Role in health 
Much of the world's disease is caused by the lack of clean drinking water. Lack of water in diet will eventually cause death by hypernatremia and dehydration, particularly when sweating consumes much of the body water. Unclean and unsanitary water can contain many bacteria and parasites that would otherwise be absent in clean water. Studies show that in some developing countries more than half of the population does not have access to safe drinking water.
It is also possible to overhydrate, which sometimes happens with athletes who consume too much water, thereby diluting the concentration of salts in the body. Overconsumption of water can be a sign of disease and/or mental health problems(e.g. damage to the hypothalamus), as stated above.
Fluid restriction 
Fluid restriction or water restriction occurs when a person intentionally abstains from drinking water (or other beverage for hydration), either partially or completely.
Partial fluid restriction can be used in medicine, but have the disadvantages of being difficult to maintain, and it is often ineffective. Drugs causing increased diuresis (diuretics) is generally an alternative, and have less risk of causing decreased glomerular filtration rate through the kidneys and resultant decreased kidney function. Fluid restriction is occasionally a practice in management of heart failure. However, according to a review in 2009, there is apparently no evidence of benefit of fluid restriction in patients with clinically stable heart failure otherwise receiving optimal pharmacological treatment. Rather, diuretics are preferred in heart failure, mainly ACE inhibitors, with substantial evidence of improving survival and quality of life in heart failure patients. Theoretically, fluid restriction could also correct the electrolyte imbalance in hyponatremia, but again, diuretics, mainly vasopressin receptor antagonists, show better efficiency. Nevertheless, in hyponatremia secondary to SIADH, long-term fluid restriction (of 1,200–1,800 mL/day) in addition to diuretics is standard treatment.
Also, fluid restriction is the test of choice to distinguish primary polydipsia from diabetes insipidus. In primary polydipsia, the urine osmolality should increase and stabilize at above 280 Osm/kg with fluid restriction, while a stabilization at a lower level indicatess diabetes insipidus. Stabilization in this test means, more specifically, when the hourly increase in osmolality is less than 30 Osm/kg per hour for at least 3 hours.
Fluid restriction can also be part of religious practice, such as being part of the fasting from dawn till dusk in the Ramadan period for Muslims. During the daylight hours of Ramadan fasting, practising Muslims are dehydrating, but it is not clear whether this is chronic during the month of Ramadan. No detrimental effects on health have as yet been directly attributed to negative water balance at the levels that may be produced during Ramadan.
Alcoholic beverages 
“Drinking” is often used metonymically as a synonym for the consumption of alcoholic beverages. Most cultures throughout history have incorporated some number of the wide variety of "strong drinks" into their meals, celebrations, ceremonies, toasts and other occasions. The earliest known evidence of fermented drinks in human culture dates to 8,000 BC.
The drinking of alcohol has developed into a variety of well-established drinking cultures around the world. Despite its popularity, alcohol consumption poses significant health risks. Alcohol abuse and the addiction of alcoholism are common maladies worldwide. A high rate of consumption can also lead to cirrhosis, gastritis, gout, pancreatitis, hypertension, various forms of cancer, and numerous other illnesses.
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