This material was created within the european E-classes project under the Erasmus+ program. Water treatment and water pollution. Water is a fascination topic to discuss. Did you know that water is the only substance that is found naturally on Earth in three forms: liquid, gas and solid? Did you know that 90% of the Earth water is salty, 2.1% is locked up in polar ice caps and less than 1% is available as fresh water. Did you know that hot water freezes faster than cold water? This is known as Mpemba effect and no one knows why it happens. Why is water important? Water is essential to life. We can live without anything except air and water. More than 60% of our body is water. Water covers over 70% of the Earth surface. All plants and animals must have water to survive. If there was no water, there would be no life on Earth. Our body uses water in all its cells, organs and tissues to maintain bodily functions. Apart from drinking it to survive people have many other uses for water. These include cooking, washing their bodies, clothes and cooking utensils, keeping houses and communities clean or recreation such as swimming pools. Water is also essential for the healthy growth of farm crops and farm animals and it is used in the manufacture of many products. Water is a source of life and beauty. In spite of this we pollute our waters. Some of the most common water pollutants are: domestic waste, chemicals, fertilisers and plastic. What are the effects of water pollution? They are visible on people and our environment. Water pollution is harmful to human health. Garbage dumped in waters kills animals and plants. What about the water we drink? Do you know where you get your drinking water from? What are your sources of water? Of drinking water? Well, I do. If you live in Iasi Romania, you get your drinking water from this lake: Chirita lake. Well, don’t worry: a lot happens to this water before we drink it. Before we drink it the water from lakes and rivers is treated in a treatment water plant. Pumps draw raw water from the lake to the treatment water plant. The water treatment process begins here. The first step in the cleaning process removes big sediments from the water. Then water is filtered through layers of sand and coal. The water is not completely clean yet. It is filtered but it may be infected with bacteria, germs or viruses. The next step, disinfection, removes them with the help of chlorine and ozone. Now water is ready for distribution. We monitor our water quality by having it tested regularly. This is an important part for maintaining it safe and reliable. It is important to test if our water is suitable for its intended purposes: whether it is livestock watering, irrigation spraying or drinking water. Let’s take care of our water resources! Without water conservation we won’t go very far. It is central in making sure the world has better access to clean water. It means being aware that water is a limited resource, taking care of it and managing it responsibly.