Many houses in large cities receive piped water from rivers or dams. This water is subjected to special treatments to eliminate impurities and health-damaging microbes.
First, water from the river or dam is carried through thick pipes, called water mains, to water treatment plants. Once purified, the water is taken to large reservoirs and then distributed to the houses.
At the treatment plant, water passes through cement tanks and receives products such as aluminum sulfate it's the calcium hydroxide (hydrated lime). These substances make the fine particles of sand and clay present in the water come together, forming larger particles, the flakes. This process is called flocculation. As these particles are larger and heavier, they gradually settle to the bottom of another tank. settling tank. In this way some solid impurities in the water are retained.
After a few hours in the settling tank, the water that is above the impurities, which is cleaner, passes through a filter formed by several layers of small stones (gravel) and sand. As the water passes through the filter, any unpaved sand or clay particles get trapped in the spaces between the sand grains. Some of the microbes also get stuck in the filters. It is the step known as filtration.
But not all microbes that can cause disease deposit at the bottom of the tank or are trapped by the filter. Therefore, water receives products containing the element chlorine, which kills microbes (chlorination), and the fluorine, an important mineral for teeth formation.
Water is then carried through underground pipelines to houses or buildings.
Even those who receive water from the treatment plant must filter it for consumption. This is because there may be contamination in the water tanks of buildings or houses or leaks in the pipes. Water tanks should always be well capped and cleaned at least every six months. In addition, at certain times when the risk of waterborne diseases increases, additional care must be taken.