It is dirty and has lots of things living or floating in it.
We clean the water to take the colour and the dirt out of it and to remove any germs. The germs that can be found in unclean water could cause diseases like typhoid, cholera and diarrhoea. It is these diseases that cause nearly 6000 children to die everyday in the developing world. Even at the beginning of the 20th century these diseases were killing people in this country.
There are four main stages in water treatment:
Filtering the water to trap anything floating in it
Disinfection killing any germs
Although the water looks very clean it still contains germs, which are the most important things we need to get rid of as they can make us very poorly. We use a chemical called chlorine to kill the germs.
At all points along the way the water is continuously tested and monitored to ensure the right amount of chemicals are being added and that the water is flowing smoothly. Now the water is clean and safe to drink it can be sent down the water pipes to our homes, schools, businesses, leisure centres, etc.