World Water Day

Water Day, by the years

In 2014, the UN System – working closely with its Member States and other relevant stakeholders – is collectively bringing its attention to the water-energy nexus, particularly addressing inequities, especially for the 'bottom billion' who live in slums and impoverished rural areas and survive without access to safe drinking water, adequate sanitation, sufficient food and energy services. It also aims to facilitate the development of policies and crosscutting frameworks that bridge ministries and sectors, leading the way to energy security and sustainable water use in a green economy. Particular attention will be paid to identifying best practices that can make a water- and energy-efficient 'Green Industry' a reality.

What do you know about water issues?

Discover this updated and expanded series of Water Factsheets proposed by UN-Water to use in your efforts towards awareness raising of issues related to water.

These thematic factsheets present a series of quick facts on a range of issues including water scarcity, climate change, sanitation, water and urbanization, water quality, transboundary waters, water and food, water and disasters, water and biodiversity.
 

• Water is made up of two elements, hydrogen and oxygen. Its chemical formula is H₂O.
• Each molecule of water is made up of two hydrogen atoms bonded to a single oxygen atom.
• The existence of water is essential for life on Earth.

• Water has three different states, liquid, solid and gas.

• The word water usually refers to water in its liquid state. The solid state of water is known as ice while the gas state of water is known as steam or water vapor.

• Water covers around 70% of the Earth’s surface.

• The three largest oceans on Earth are the Pacific Ocean (largest), the Atlantic Ocean (second largest) and the Indian Ocean (third largest). Found in the Pacific Ocean, the Mariana Trench is the deepest known point in the world’s oceans.

• Ocean tides are caused by the rotation of the Earth and the gravitational pull of the Moon and Sun acting on ocean water.

• Water from a sea or ocean is known as seawater. On average, every kilogram (2.2lb) of seawater contains around 35 grams (1.2 oz) of dissolved salt.

• The freezing point of water lowers as the amount of salt dissolved in at increases. With average levels of salt, seawater freezes at -2 °C (28.4 °F).

• The longest river in the world is the Nile River, it reaches 6650 kilometers in length (4132 miles).
• The second longest river in the world is the Amazon River, it reaches 6400 kilometres (4000 miles) in length.

• The longest river in the USA is the Missouri River. At around 2,340 miles (3,770 km) in length it is slightly longer than the Mississippi River (2,320 miles). The two combine to form the longest river system in North America.

• Water makes a good solvent with many sugar, salts and acids easily dissolving in it. On the other hand oils and fats don’t mix well with water.

• The water cycle involves water evaporating (turning into a gas), rising to the sky, cooling and condensing into tiny drops of water or ice crystals that we see as clouds, falling back to Earth as rain, snow or hail before evaporating again and continuing the cycle. Learn more about the water cycle.

• Water in the form of ice is found at the polar ice caps of the planet Mars, some scientists have also suggested the possibility of liquid water on the red planet.

• Pure water has no smell and no taste, it also has a pH level around 7.

• While most people know that water boils at 100 °C (212 °F), this is at the normal conditions of sea level. The boiling point of water actually changes relative to the barometric pressure. For example, water boils at just 68 °C (154 °F) on the top of Mount Everest while water deep in the ocean near geothermal vents can remain in liquid form at temperatures much higher than 100 °C (212 °F).
• Water expands as it cools from 4 °C to 0 °C (above 4 °C it does the opposite). In freezing conditions, water has been known to burst water pipes as it freezes to ice.
• Water can move up narrow tubes against the force of gravity in what is known as capillary action. Check out this capillary action experiment for more.
• Most people around the world have access to clean drinking water but it is a major problem in poorer areas of the world. Water pollution and low quality water can lead to dangerous bacteria, disease and viruses such as E coli and Cryptosporidium.
• Drinking water is needed for humans to avoid dehydration, the amount you need each day depends on the temperature, how much activity you are involved in and other factors.
• An important use for water is in agricultural irrigation, this is when water is artificially added to soil in order to assist the growth of crops.
• Water is used frequently by firefighters to extinguish fires. Helicopters sometimes drop large amount of water on wildfires and bushfires to stop fires spreading and limit the damage they can cause.
• The water industry helps deliver water to homes in various cities and countries around the world. This can involve services such as purification, sewage treatment, filtering, distillation and plumbing.
• Electricity can be created from hydropower, a process that uses water to drive water turbines connected to generators. There are many hydroelectric power stations around the world.
• Water also plays a role in cooking. Steaming and boiling food are well known cooking methods. You may have noticed this last time you made pasta or noodles.
• Water is also used for fun. Water sports are a very popular recreational activity and include things like swimming, surfing and waterskiing. Ice and snow is also used in ice skating, ice hockey, skiing and snowboarding.

Hydroelectricity

Hydroelectricity is the largest renewable source for power generation and its share in total electricity generation is expected to remain around 16% through 2035.

   

Hydropower and water use

Most of the water used for hydropower generation is returned to the river though some evaporates and there are important impacts on timing and quality of streamflows.

   

Industrial water use

Roughly 75% of all industrial water withdrawals are used for energy production.

   

Financing water

For developing countries alone $103 billion per year are required to finance water, sanitation and wastewater treatment through 2015.

   

Energy for water

Energy is required for two components of water provision: pumping and treatment (before and after use).

   

Waterborne transportation

Waterborne transit is one of the most energy efficient. Inland towing barges are more than 3 times more energy efficient than road trucks and 40% more efficient than rail.

   

Biogas produced from sewage

In Stockholm, public buses, waste collection trucks and taxis run on biogas produced from sewage treatment plants.

   

Access to water and sanitation

In 2011, 768 million people did not use an improved source of drinking-water and 2.5 billion people did not use improved sanitation.

   

Access to electricity

More than 1.3 billion people still lack access to electricity, and roughly 2.6 billion use solid fuels (mainly biomass) for cooking.

   

Wind power

Wind power is the most sustainable source of renewable energy, mainly because of its low greenhouse gas emissions and water consumption.

   

Pollution by fossil fuels

Approximately 15–18 billion m3 of freshwater resources are contaminated by fossil fuel production every year.

   

Biodiesel and water

China's target to produce 12 million metric tonnes of biodiesel by 2020 requires an amount of water approximately equivalent to the annual discharge of the Yellow River.

   

Biofuels and food prices

The demand for biofuels feedstock is the largest source of new demand for agricultural production in decades, and it was a major factor behind the 2007−08 spike in food prices.

   

Geothermal electricity potential

The installed worldwide geothermal electricity capacity could be increased from the current 10 GW to 70 GW with present technology, and to 140 GW with enhanced technology.