Great question.

H2O is the chemical name for water. The O in H2O stands for Oxygen.  The H is Hydrogen.  A water molecule is made up of 2 Hydrogen molecules (H2) and an Oxygen (O) molecule.

Water is a solid (in ice and snow), liquid (in creeks and coming out of taps) and a gas (all around us called water vapour but which is invisible). Water evaporates and turns into a gas, it has no colour or smell. It evaporates with the help of heat from puddles, lakes, oceans, soil and the wet clothes hanging on the clothesline. Although we cannot see water in its gaseous state, we can feel it in the air on a hot, humid day. You can "see" water vapour through the electromagnetic eyes of infrared-sensing instruments.

The experts say water is a blue colour because of the structure and behaviour of its molecules but we see water as many colours. Light makes water look different colours because the particles in water can absorb, reflect or scatter light. Glacial lakes are a beautiful turquoise because they contain finely ground rock from the glaciers. Some rivers are brown because they are filled with soil that is washed in by rain. Algae growing in the water will make it green, blue or even pink. Clouds’ shadows and water depth help change the water colour too. However our drinking water from the tap is clear. This is a result of the water treatment process. Humans like to drink water that has no colour, no smell and no taste and these are removed through the filtering, disinfection and other stages at the Water Treatment Plant.

On average a person uses 180 to 225 litres of water a day. That is 20 to 25 buckets. We only drink about 2 litres a day so the rest is used for cooking, showering, washing, flushing, cleaning, gardening and other things in our daily living.

H20 is the chemical formula of water. It shows that one molecule of water consists of one atom oxygen and two atoms of hydrogen.

When water evaporates it is changing from a liquid to a gas called water vapour. Heat (energy) is necessary for evaporation to occur. The energy from the sun makes the water molecules in a lake or the ocean move faster and faster. This breaks the bonds that hold those water molecules together and allows some to escape into the air. Evaporation is an essential part of the water cycle.

When you heat water in the kettle or a pot, water vapour bubbles form at boiling point. This happens because the heat (energy) makes the water molecules move faster and faster. The water molecules get enough energy to break the forces that hold them together. They can then move around freely in the gaseous state and gas bubbles rise and break through the surface into the air.

Oxygen dissolved in water means fish and other aquatic creatures can breathe and live underwater. They have also developed ways to live with high salt levels. For example fish's kidneys pump excess salt into their urine. Albatrosses have salt glands just behind their eye sockets. These drain a salty solution out through the tip of their beak. And a gland in the shark's digestive system gets rid of excess salt.

Although you don’t see it, just about everything we eat, own or use daily has water in it or water was used to make or produce it. Water is used in the production processes to cool, mix, heat, wash and dye things as they are made in factories. For example paper, plastic, metal and fabric depend on water to make and clean their product. We grow our food with water and most foods have a high water content. The term “water footprint” has been develop for us to find out how much water is in our goods and products and to really understand the cost and dependency we have on water, more information at www.waterfootprint.org

About 75% of our bodies are actually water; it is in our blood, lungs, cells and bone. Water is essential for our bodies: It helps to regulate our internal body temperature; metabolises and transports carbohydrates and proteins (food) in our bloodstream; flushes out our wastes (urine), acts as a shock absorber for our brain and spinal cord and lubricates our joints. We breathe, wee and sweat water out so it is vital we drink every day to avoid dehydration and maintain a healthy body.

The air is full of water. Most of the time water vapour in the air cannot be seen unless it collects and condenses to form a cloud. When you look into the sky and see a cloud, it is actually moisture you are seeing. The water molecules in the air collect on surfaces like dust from volcanoes, cars, sea spray or fires. As the temperatures decrease, the water vapour condenses changing from gaseous water to liquid water and becomes a cloud.

When water evaporates it changes from its liquid form to its vapour form. This means the water is transferred from land to the atmosphere. How quickly this happens will be affected by how windy, hot or humid it is. The most evaporation will occur on days with high wind speed, high temperature and low humidity.

Our planet has billions and billions of litres of water but most of it is salty, only 1% is fresh and available for our use. People are already living in areas that have low rainfall, droughts or where the water has been polluted; they are living in areas of high water stress. Therefore water is a very important issue for us all but if we work together we won’t run out. Everyone must help to save water, even on the rainy days. At home we can take small actions to save water like having a quick shower. Local governments can apply water restrictions. State government have rules for new homes to be built with rainwater tanks and water efficient taps and toilets. Also Inventors and Scientists are coming up with a range of technologies that help deal with water wastage, clean dirty water and turn salty water into fresh water.

I don’t think we will run out of water but we all know a lot of water is wasted every day. Firstly it is the responsibility of everyone at home, at school, at work and during recreation to use water wisely for today and for the future. Secondly it is hard to imagine, but how water is used today will be very different to how it is used in 100 years’ time. New technologies for homes, farms and factories will be developed to use the water we have more wisely and ensure we never run out.

Without water our body would stop working properly. Water makes up more than half of our body weight and we can't survive for more than a few days without it. It helps to carry nutrients and oxygen to the cells in our body and to carry away waste products from the body. We need water to digest our food and lubricate our joints. Water also helps regulate our body temperature by absorbing heat generated by metabolism and eliminating excess heat through sweating. As well it provides a moist environment for ear, nose and throat tissues.We should be drinking about 8 glasses of water a day.

This is a great question because it shows that we don’t know everything.  It is one of the wonderful parts of understanding our world that sometimes some things may never be known.

The most common element in the universe is called hydrogen (H). This is one of the two elements that make up water (H2O). H is the first element known to have existed since the formation of the universe. Oxygen (O) is thought to have formed in the process of supernova. Supernovas are massive explosions of old stars.

The Earth itself appears to have taken a long time to form. This is because it accumulated over time from the particles and elements left over by the supernova and pulled together by gravitational attraction. It is probable that by approximately 9 000 000 000 to 10 000 0000 000 years ago the Earth had become a round shaped planet.

Water itself was probably not present in the early stages but the elements H and O may have been present chemically contained in minerals on the young planet.  At some point OH- formed. Either the energy from the young Sun and from the nuclear decay of radioactive elements in the Earth bonded H and O together to form OH. Or OH- in minerals contained in comets may have added water to the earth when they collided with the Earth.  OH- is chemically unstable compared to individual O and H elements in minerals and it is therefore relatively easy to add an extra H atom to OH- to become H2O. Because of the heat of the early earth the water would have been present mostly as a vapour (steam) but as the earth cooled more and more would have become liquid. The presence of steam actually helped to create the Earth’s atmosphere too and acted as an insulator that helped to stabilise massive temperature fluctuations in the atmosphere, just as it does in our atmosphere today.

Without water our body would stop working properly and remember we are breathing, weeing and sweating it out during the day. Health experts say we should drink about 8 glasses of water a day to keep hydrated. Even mild dehydration can drain your energy and make you tired. But sometimes we may need more if we are doing a lot of exercise or it is very hot.

Water evaporates because when it is heated, the water molecules move faster and faster until they break free from the bonds that hold them in place as a liquid. As these H2O molecules escape they have turned from a liquid to a gas and are invisible to us.

Some scientists say evidence shows that comets brought water vapour to Earth. Different scientists think that the very first atmosphere of the Earth must have been made of gasses such as hydrogen and oxygen which are the atoms in the water molecule.  And another theory is magma in volcanic activity put water into the atmosphere. Whichever theory, once the water vapour could cool into a liquid, collect on land, evaporate into vapour again, the never ending, ongoing water cycle was underway.

Think about water lying in a puddle with the sun shining down. As this liquid water is warmed, the water molecules move faster and faster. Evaporation happens as some of the water molecules at the surface of the puddle are moving fast enough to break the bonds with other water molecules. As they escape they are changing from a liquid to a gas.

Everything is made of atoms and atoms join together to form molecules. A water molecule has three atoms: two hydrogen (H) atoms and one oxygen (O) atom. That is why water is called H2O. Oxygen has a negative charge and the hydrogen a positive charge. A molecule that has (+) and (-) poles act like a magnet. The (+) end of the one water molecule attracts the (-) end another molecule's. This arrangement holds water molecules together.

Water appears to us as many colours but very small amounts of water are colourless. Water looks blue because of the way white light is absorbed and scattered. White water is due to tiny air bubbles being dispersed through the water. This can occur in a water fall or coming out of a tap with an aerator. These are a common water saving tap model.

Water is formed when two hydrogen atoms bond to one oxygen atom - H2O.

Water exists in three different states; as a solid, liquid or gas. When water is in its solid state (ice) the water molecules are packed close together in a lattice pattern. When ice is warmed it melts and becomes liquid water. Now the attractive forces between the molecules weaken and can slip and slide around one another. Water as a liquid takes the shape of the container it is in. In its gaseous state (water vapour) the water molecules can move very rapidly and are not bound together. Although we cannot see water in its gaseous state, we can feel it in the air on a humid day.

Water is cleaned during the water cycle; it is filtered by trees and sand and strong sun light, (UV light rays), kill bacteria, viruses, moulds and spores. Water is also cleaned, filtered and disinfected at Water Treatment Plants. Look up your local water authority on the web to find out the processes that make the water in your taps come out clean and healthy.

Each person needs to drink about two litres of water a day. With 365 days in a year that would be 730 litres or about 81 buckets.