About 70% of
the fat free mass of the human body is made of water. To function
properly, the body requires between one and seven liters of water per
day to avoid dehydration; the precise amount depends on the level of
activity, temperature, humidity, and other factors.
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 most experts agree that 8–10 glasses of water
(approximately 2 liters) daily is the minimum to maintain proper
hydration. For those who do not have kidney problems, it is rather
difficult to drink too much water, but (especially in warm humid
weather and while exercising) it is dangerous to drink too little.
drink far more water than necessary while exercising, however, putting
them at risk of water intoxication, which can be fatal. The "fact" that
a person should consume eight glasses of water per day cannot be traced
back to a scientific source. There are other myths such as the effect
of water on weight loss and constipation that have been dispelled.
One liter of water was used to determine the weight of a kilogram. Unfortunately, the measurement of water was taken at one degree Celcius. Water is its most dence at four degrees Celcius. Thus the measurement was actually not correct.
As a solvent:
Dissolving (or suspending) is used to wash everyday items such as the human body, clothes, floors, cars, food, and pets.
As a thermal transfer agent:
Boiling, steaming, and simmering are popular cooking methods that often require immersing food in water or its gaseous state, steam.
Water is also used in industrial contexts as a coolant, and in almost all power-stations as a coolant and to drive steam turbines to generate electricity.
In the nuclear industry, water can also be used as a neutron moderator.
Humans use water for many recreational purposes, as well as for exercising and for sports. Some of these include swimming, waterskiing, boating, fishing, and diving. In addition, some sports, like ice hockey and ice skating, are played on ice.
Lakesides and beaches are popular places for people to go to relax and enjoy recreation.
Many find the sound of flowing water to be calming, too.
Some keep fish and other life in water tanks or ponds for show, fun, and companionship.
Humans also use water for snow sports i.e. skiing or snowboarding, which requires the water to be frozen. People may also use water for play fighting such as with snowballs, water guns or water balloons.
Pressurized water is used in water blasting and water jet cutters.
Also, very high pressure water guns are used for precise cutting. It works very well, is relatively safe, and is not harmful to the environment.
Water plays many critical roles within the field of food science. It is important for a food scientist to understand the roles that water plays within food processing to ensure the success of their products.
Solutes such as salts and sugars found in water affect the physical properties of water. The boiling and freezing points of water is affected by solutes. One mole of sucrose (sugar) raises the boiling point of water by 0.52 °C, and one mole of salt raises the boiling point by 1.04 °C while lowering the freezing point of water in a similar way. Solutes in water also affect water activity which affects many chemical reactions and the growth of microbes in food.
Water activity can be described as a ratio of the vapor pressure of water in a solution to the vapor pressure of pure water. Solutes in water lower water activity. This is important to know because most bacterial growth ceases at low levels of water activity. Not only does microbial growth affect the safety of food but also the preservation and shelf life of food.
Water hardness is also a critical factor in food processing. It can dramatically affect the quality of a product as well as playing a role in sanitation. Water hardness is classified based on the amounts of removable calcium carbonate salt it contains per gallon.
Water hardness is measured in grains; 0.064 g calcium carbonate is equivalent to one grain of hardness. Water is classified as soft if it contains 1 to 4 grains, medium if it contains 5 to 10 grains and hard if it contains 11 to 20 grains. The hardness of water may be altered or treated by using a chemical ion exchange system. The hardness of water also affects its pH balance which plays a critical role in food processing. For example, hard water prevents successful production of clear beverages.
Water hardness also affects sanitation; with increasing hardness, there is a loss of effectiveness for its use as a sanitizer.
Hydroelectricity is electricity obtained from hydropower. Hydroelectric power comes from water driving a water turbine connected to a generator. Hydroelectricity is a low-cost, non-polluting, renewable energy source.
"To the people of poor nations, we
pledge to work alongside you to make
your farms flourish and LetCleanWatersFlow, to nourish starved
bodies and feed hungry minds. And to those nations like ours that enjoy
relative plenty, we say we can no longer afford indifference to
suffering outside our borders; nor can we consume the world's resources
without regard to effect. For the world has changed, and we must change
with it". Source: President Obama, Inaugural Speech, January 20, 2009, Washington, DC, USA.