Drinking Water

1.227 km of water supply network

Responsible for the intake, treatment, conveyance, and distribution of water to the municipality of Braga, AGERE operates various equipment for this purpose. Daily, approximately 32,000 m³ of potable water are provided under conditions of excellence and safety.

The supply system consists of 4 stages

Production

Water is captured from the Cávado River and treated at the Water Treatment Plant (ETA) located at Ponte do Bico.

Transportation

Conveyance, through an elevated pipeline, from the Water Treatment Plant (WTP) to the main reservoir of the municipality, located in Montariol.

Storage

Water storage is distributed across various reservoirs in the municipality.

Distribution

It includes the network that delivers water to the consumer.

Water Treatment

01

02

03

04

05

06

07

Phase 01

Grading

Raw water is captured directly from the left bank of the river through two free-entry channels leading to two intake wells, one upstream and one downstream. This initial phase, known as grading, allows for the separation of large solids such as logs or plastics. The upstream well is equipped with two lift pumps, one with a capacity of 200 l/s and another with 400 l/s. The downstream well has three lift pumps: two with 200 l/s capacity each and one with 400 l/s capacity.

Phase 02

Tamisation

After elevation, the raw water undergoes a screening process. This system, composed of vertical continuous screens, allows for the separation of smaller solids such as leaves, branches, or algae.

Phase 03

Pre-oxidation with chlorine gas

Next comes pre-oxidation, which is carried out with water previously chlorinated (using chlorine gas) in an amount sufficient to promote the oxidation of all suspended organic matter, including microorganisms present, thereby preventing their proliferation in the filtration bed.

Phase 04

Coagulation/Flocculation with a polyaluminum chloride

Coagulation takes place in the rapid mixing chamber, where a polyaluminum chloride is used as a coagulant. This process aims to remove colloidal organic matter by forming flocs, which will then be retained during the rapid filtration phase through sand filters.

Phase 05

Direct Filtration in Sand Filters

After coagulation and flocculation, the water passes through a channel that feeds a battery of open filters with calibrated sand. The water to be filtered is distributed through distributors across the eight AQUAZUR-type filters. This process aims to retain the flocs formed in the previous treatment stage and the suspended matter.

Phase 06

Remineralization with lime water and carbon dioxide

There is a need for remineralization because the waters from the northern area are slightly acidic (pH between 5.5 and 6), poorly mineralized, and thus aggressive towards the pipes. This process aims to adjust the water and involves correcting the water's aggressiveness and pH by adding lime water and CO2. Calcium hydroxide (lime) and CO2 are used because they do not introduce foreign elements into the natural composition of the water and are harmless to health.

Promotes the formation of calcium bicarbonate, leading to the stabilization of the pH to a value close to neutral (pH=7).

Phase 07

Final disinfection with chlorine gas

Finally, with the final disinfection (carried out with chlorinated water), the aim is to ensure microbiological quality and maintain a residual disinfectant level in the water that reaches consumers.
After treatment, the water is pumped through the supply pipelines to the Pintacinhos and Montariol reservoirs, with capacities of 4,000 m³ and 32,000 m³, respectively.