Water











 Water is a transparent and nearly colorless chemical substance that is the main constituent of Earth's streams, lakes, and oceans, and the fluids of most living organisms.


Its chemical formula is H2O, meaning that its molecule contains one oxygen and two hydrogen atoms, that are connected by covalent bonds. Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure; but it often refers also to its solid state (ice) or its gaseous state (steam or water vapor). It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, and atmospheric humidity.

Water covers 71% of the Earth's surface. It is vital for all known forms of life. On Earth, 96.5% of the planet's crust water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in the air as vapor, clouds (formed of ice and liquid water suspended in air), and precipitation. Only 2.5% of this water is freshwater, and 98.8% of that water is in ice (excepting ice in clouds) and groundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth's freshwater (0.003%) is contained within biological bodies and manufactured products. A greater quantity of water is found in the earth's interior.

Water on Earth moves continually through the water cycle of evaporation and transpiration (evapotranspiration), condensation, precipitation, and runoff, usually reaching the sea. Evaporation and transpiration contribute to the precipitation over land. Large amounts of water are also chemically combined or adsorbed in hydrated minerals.

Safe drinking water is essential to humans and other lifeforms even though it provides no calories or organic nutrients. Access to safe drinking water has improved over the last decades in almost every part of the world, but approximately one billion people still lack access to safe water and over 2.5 billion lack access to adequate sanitation. There is a clear correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%.

Water plays an important role in the world economy. Approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a major source of food for many parts of the world. Much of long-distance trade of commodities (such as oil and natural gas) and manufactured products is transported by boats through seas, rivers, lakes, and canals. Large quantities of water, ice, and steam are used for cooling and heating, in industry and homes.

Water conservation includes all the policies, strategies and activities made to sustainably manage the natural resource fresh water, to protect the water environment, and to meet the current and future human demand. Population, household size, and growth and affluence all affect how much water is used. Factors such as climate change have increased pressures on natural water resources especially in manufacturing and agricultural irrigation. Many US cities have already implemented policies aimed at water conservation, with much success.

The goals of water conservation efforts include:

Ensuring availability of water for future generations where the withdrawal of fresh water from an ecosystem does not exceed its natural replacement rate.
Energy conservation as water pumping, delivery, and wastewater treatment facilities consume a significant amount of energy. In some regions of the world over 15% of total electricity consumption is devoted to water management.
Habitat conservation where minimizing human water use helps to preserve fresh water habitats for local wildlife and migrating waterfowl, but also water quality

Strategies

The key activities that benefit water conservation(save water) are as follows:

Any beneficial reduction in water loss, use, and waste of resources.
Avoiding any damage to water quality.
Improving water management practices that reduce the use or enhance the beneficial use of water.


One strategy in water conservation is rainwater harvesting. Digging ponds, lakes, canals, expanding the

water reservoir, and installing rainwater catching ducts and filtration systems on homes are different

methods of harvesting rainwater.

Harvested and filtered rainwater could be used for toilets, home gardening, lawn irrigation, and small-scale agriculture.


Another strategy in water conservation is protecting groundwater resources.

When precipitation occurs, some infiltrates the soil and goes underground. Water in this saturation zone

is called groundwater. Contamination of groundwater causes the groundwater water supply to not be able

to be used as resource of fresh drinking water and the natural regeneration of 

replenish. Some examples of potential sources of groundwater contamination include storage tanks, septic systems,

uncontrolled hazardous waste, landfills, atmospheric contaminants, chemicals, and road salts. Contamination of groundwater decreases the replenishment of available freshwater so taking preventative measures by protecting groundwater resources form contamination is an important aspect of water conservation.

An additional strategy to water conservation is practicing sustainable methods of utilizing groundwater resources. Groundwater flows due to gravity and eventually discharges into streams. Excess pumping of groundwater leads to a decrease in groundwater levels and if continued it can exhaust the resource. Ground and surface waters are connected and overuse of groundwater can reduce and, in extreme examples, diminish the water supply of lakes, rivers, and streams. In coastal regions, over pumping groundwater can increase saltwater intrusion which results in the contamination of groundwater water supply. Sustainable use of groundwater is essential in water conservation.

A fundamental component to water conservation strategy is communication and education outreach of different water programs. Developing communication that educates science to land managers, policy makers, farmers, and the general public is another important strategy utilized in water conservation Communication of the science of how water systems work is an important aspect when creating a management plan to conserve that system and is often used for ensuring the right management plan to be put into action






























House hold  applications

The Home Water Works website contains useful information on household water conservation. Contrary to popular view, experts suggest the most efficient way is replacing toilets and retrofitting washers

Water-saving technology for the home includes:

Low-flow shower heads sometimes called energy-efficient shower heads as they also use less energy
Low-flush toilets and composting toilets. These have a dramatic impact in the developed world, as conventional Western toilets use large volumes of water
Dual flush toilets created by Caroma includes two buttons or handles to flush different levels of water. Dual flush toilets use up to 67% less water than conventional toilets
Faucet aerators, which break water flow into fine droplets to maintain "wetting effectiveness" while using less water. An additional benefit is that they reduce splashing while washing hands and dishes
Raw water flushing where toilets use sea water or non-purified water
Wastewater reuse or recycling systems, allowing:

Reuse of greywater for flushing toilets or watering gardens
Recycling of wastewater through purification at a water treatment plant. See also Wastewater - Reuse

Rainwater harvesting
High-efficiency clothes washers
Weather-based irrigation controllers
Garden hose nozzles that shut off the water when it is not being used, instead of letting a hose run.
Low flow taps in wash basins
Swimming pool covers that reduce evaporation and can warm pool water to reduce water, energy and chemical costs.
The automatic faucet is a water conservation faucet that eliminates water waste at the faucet. It automates the use of faucets

without the use of hands.

Commercial applications

Many water-saving devices (such as low-flush toilets) that are useful in homes can also be useful for business water saving.





Water Reuse

A region where the demand for water exceeds its supply. The imbalance between supply and demand, along with persisting

issues such as climate change and exponential population growth, has made water reuse a necessary method for conserving water.

There are a variety of methods used in the treatment of waste water to ensure that it safe to use for irrigation of food crops

and/or drinking water.

Seawater desalination requires more energy than the desalination of fresh water. Despite this, many seawater desalination

plants have been built in response to water shortages around the world. This makes it necessary to evaluate the impacts of

seawater desalination and to find ways to improve desalination technology. Current research involves the use of experiments

to determine the most effective and least energy intensive methods of desalination.

Sand filtration is another method used to treat water. Recent studies show that sand filtration needs further

improvements, but it is approaching optimization with its effectiveness at removing pathogens from water. 

Sand filtration is very effective at removing protozoa and bacteria, but struggles with removing viruses. 

Large-scale sand filtration facilities also require large surface areas to accommodate them.

The removal of pathogens from recycled water is of high priority because wastewater always contains pathogens

capable of infecting humans. The levels of pathogenic viruses have to be reduced to a certain level in order for

recycled water to not pose a threat to human populations. Further research is necessary to determine more accurate

methods of assessing the level of pathogenic viruses in treated wastewater.




 References: https://en.wikipedia.org/wiki/Water_conservation             https://en.wikipedia.org/wiki/Water