What is an ETAP?
When we talk about the management of drinking water, it is inevitable to wonder how water, from its different sources, reaches our homes converted into drinking water. As we mentioned in previous articles , supply systems collect water from different sources: rivers, streams, reservoirs, wells, springs, reservoirs, among others. Once that raw, untreated water is stored, that is when the ETAP .
When we talk about ETAP we refer to the Drinking Water Treatment Station, also known as the Potabilizadora. It is an industrial facility in which the appropriate treatments are carried out to precisely make all that water collected and stored from different sources become completely safe and suitable for human consumption.
How does an ETAP work?
Although its appearance at first glance is that of a perfect water to drink, the water that reaches the water treatment plants contains numerous pollutants that are harmful to health. These biological, chemical and even radioactive pollutants must be completely eliminated through the appropriate treatments.
Although there are various types of water treatment plants, normally, to achieve this end, they carry out a series of continuous processes whose generalized sequence is as follows:
- Pretreatment or pre-sedimentation: The water reaches a large deposits in which settleable solids are removed. The heavier particles fall to the bottom when the water movement stops.
- Flocculation: the coagulation or flocculation process consists of adding chemical additives to the water to promote the sedimentation of non-sedimentable colloidal matter or to accelerate the sedimentation through the formation of flocs. Flocs are groups of small particles agglutinated into larger particles with a greater sedimentation capacity.
- Sedimentation: Due to the effect of gravity, the flocs settle to the bottom of the tanks to be eliminated.
- Filtration: The water passes through a porous medium that is responsible for retaining the remaining impurities. Once this phase is finished, the water will be completely clean, although it will not yet be suitable for consumption.
- Disinfection: In this phase the bacterial load of the water is reduced. This treatment is carried out with different methods, either ozone or ultraviolet rays for its subsequent chlorination that will achieve clean water and, now, totally drinkable.
The arrival of water at home
After disinfection, before reaching homes, the water must pass strict controls that verify the real quality of the product obtained in the water treatment plant. Thus, in Spain, it is the National Information System for Drinking Water, the body in charge of this control and the collection of data on the characteristics and qualities of the water from the ETAP.
Once this quality is verified, the water is stored in tanks near the water treatment plants until it is transported to homes, receiving a contribution of chlorine that favors its conservation in those tanks.