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Water covers 75% of the Earth’s surface. Of this total, 97.4% is salt, and is present in the seas and oceans. Fresh water, therefore, does not reach 3%, with 90% of that volume corresponding to glaciers and only the rest is in rivers, lakes and groundwater. Hence the importance of preserving water sources.

In order to be consumed, without presenting health risks, that is, to become potable, water must be treated, cleaned and decontaminated. Water treatment is a set of physical and chemical procedures that are applied to the water so that it is in conditions suitable for consumption, that is, so that the water becomes drinkable. The water treatment process frees it from any type of contamination, preventing the transmission of diseases.

Concessionaires draw water from rivers and streams by means of pumps. This water is conducted, through the raw water mains, to the water treatment plants, also called ETAs. There it is transformed into clean and healthy water.

Usually at a Water Treatment Plant, the process follows the following steps:

 – Coagulation: when water in its natural (raw) form enters the WTP, it receives, in the tanks, a certain amount of aluminum sulfate. This substance serves to agglomerate (join) solid particles that are found in water, such as clay.

 – Flocculation – in concrete tanks with moving water, the solid particles agglutinate into larger flakes.

 – Decantation – in other tanks, by gravity, the flakes with impurities and particles are deposited at the bottom of the tanks, separating from the water.

 – Filtration – the water passes through filters formed by coal, sand and stones of different sizes. In this step, impurities of small size are retained in the filter.

 – Disinfection – chlorine is applied to water to eliminate disease-causing microorganisms.

 – Fluoridation – fluoride is applied to the water to prevent the formation of tooth decay in children.

 – PH correction – a certain amount of hydrated lime or sodium carbonate is applied to the water. This procedure serves to correct the PH of the water and preserve the distribution pipeline network.

When water is taken from underground sources, through wells, it is usually not treated in an ETA. It usually receives dosages of chlorine and fluorine in the reservoirs where it is stored.

The drinking water system is a set of structures, equipment and instruments designed to produce water for human consumption in order to deliver it to users in adequate quantity and quality, having a continuous service at a reasonable cost. Water supply systems generally contain the following components: collection works, treatment plant, distribution networks and household connections.

Producing drinking water is a constant challenge. Major investments are needed to build treatment plants and buy the necessary supplies to purify it, in addition to constant laboratory analysis to ensure that quality standards are being met. In the laboratories of the concessionaires, thousands of monthly analyzes are carried out in the parameters of Color, pH, Turbidity, E. coli and Bac Heterotrophic.

It is recommended that the consumer clean the water box in his home every 06 months, checking that the pipes in his home are in good condition, and without leaks.

Domestic sewage is made up of all the water and waste that it carries through the plumbing of houses, offices and commercial establishments. In other words, it can be said that it is all the garbage we produce using water, which goes down all the sinks and toilets, in addition to the shower and drains scattered throughout the house. Rainwater flowing down sidewalks and gutters is also mixed in sewage networks.

But where does all this sewage go? Unfortunately, most of it is not treated and ends up being deposited in rivers and seas. In Brazil, 49% of sewage is collected by treatment networks, but only 10% of all sewage produced is, in fact, treated.

Treatment is carried out at Sewage Treatment Plants (ETE). These places are able, through chemical and biological decomposition processes, imposed by the health standard of CONAMA Resolution No. 357/2005, to treat sewage.

Sewage is basically made up of 99.9% water, 0.1% solids and numerous living organisms, such as bacteria, viruses, worms and protozoa, which are released along with human waste. Even so, sewage decomposition is a process that requires several days and, therefore, a relatively expensive process, with an investment of 0.04% of the national GDP of the Federal Government.

The treatment of domestic sewage is also very important for the preservation of the environment. Sewage contaminates rivers, lakes, dams and seas because they have excess sediments and microorganisms that can cause diseases, such as schistosomiasis, leptospirosis, cholera and pyoderma.

Thus, it can transform nearby areas, unbalancing the region’s ecosystem. Rivers and beaches undergo silting up process, which is nothing more than the increase of sediments (solids) at its base, causing an increase in the water level and, consequently, floods. Sewage can also contaminate water sources and places that serve as a source of drinking water for the population. The most affected are the fish, whole species can be extinct from the place where the domestic sewage is thrown. Besides them, aquatic and riverside vegetation may end up dying. The stench is also a dangerous consequence of domestic sewage thrown into the wild.