Protecting water; how water reaches our home

The first water pipes appeared about 6,000 years ago: water came to the city through clay pipes. In ancient Rome pipes ran across tall bridges called aqueducts; ancient Samarkand also had similar water pipes. In our region a system of connected wells, the kariz, was built to use groundwater. Modern city water arrives like this: 1) pumps draw water from a river or reservoir; 2) a substance is added that sticks tiny clay particles together so they settle; 3) the water passes through filters; 4) it is disinfected to destroy bacteria and viruses; 5) it reaches a storage tank and flows through pipes to homes. Where there is no suitable source, water is taken from artesian wells. Dirty water from homes goes into sewage pipes to a treatment plant: large rubbish and sand are removed, the water is left to settle, cleaned by bacteria, disinfected and only then released to a river or field. This work is done by engineers, water-treatment specialists and plumbers.