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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 .

Convert stored water into drinking water

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:

  1. 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.
  2. 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.
  3. Sedimentation: Due to the effect of gravity, the flocs settle to the bottom of the tanks to be eliminated.
  4. 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.
  5. 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.

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Why is chlorine used in water and how does it affect health?

Chlorination is one of the processes that are carried out to treat water and its objective is to carry out a disinfection of all kinds of bacteria and pathogenic organisms. The ultimate goal of these treatments is to obtain drinking water that can be consumed by humans without risk to their health. But, is there any risk in the fact that this chemical has a presence in the water we drink? We will analyze it below.

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How does a wastewater treatment station work?

One of the bases of correct water management lies in its adequate reuse once it reaches the final phase of the cycle. At this point, it requires a process and treatment before being returned to the natural environment in optimal conditions, which is carried out precisely in the WWTP: Industrial water treatment. Dumping wastewater into rivers without carrying out the corresponding treatment implies generating an environmental impact with fatal consequences. Next we will see what this process consists of.

Clean water and sanitation

Institutions such as the UN point to clean water and sanitation as one of the Sustainable Development Goals of their Development program. To meet this objective, the treatment plants carry out this work of cleaning and treating wastewater to be able to return it to nature free of waste harmful to the environment.

What is wastewater?

They are the waters coming from homes, businesses, industry and agriculture, once they have been used for the purposes that each place requires. Thus, the water discarded from the washing machine at home, or that used to cool the turbines of a factory, is directed through the sewage network to some collectors that finally end up in the purification station. Domestic wastewater contains organic and suspended pollutants while industrial wastewater can also add heavy metals and hydrocarbons. In this way, these waters with toxic substances of inorganic nature are forced to undergo a previous treatment in the facilities where they are generated before going to the municipal collectors.

Once the domestic and industrial wastewater passes to the collector, the water purification phases will begin, which aim to eliminate organic residues such as oils, fats, sand and sedimentable solids as well as chemicals such as ammonia and phosphorus. In addition, in the last steps, the retained waste will be transformed into stable sludge that will also be reused.

How does a WWTP work?

In the treatment plant, the water will go through four well-defined phases:

  1. Pretreatment: After entering the station, larger waste is removed through screening grids that retain garbage and other bulky items; later on, it goes to tanks in which suspended sand and grease are removed thanks to mechanical processes. From here it will go to the primary decanter to continue with the process.
  2. Primary Purification: In this decanter, the water will remain at rest to favor the deposit of the heaviest residues at the bottom. These residues will generate a sludge that will be separated from the water and stored in a sludge digester prepared for this purpose.
  3. Secondary Treatment: The water passes into tanks to which oxygen bubbles are added to promote the proliferation of microorganisms that will be responsible for removing the dirt that remains. This biochemical process will eliminate organic matter such as ammonium which, if it remains, will consume the dissolved oxygen available for aquatic fauna and flora once the water is returned to the natural environment. In this phase, new sludge is created that will separate from the water and go to the sludge digester.
  4. Tertiary Treatment: In this phase a settling, filtration and disinfection of the water is carried out. After this process, the water is returned to the natural environment in the best conditions so that it can continue its cycle.

What happens to the waste after the process?

The wastewater treatment process, as we have detailed, generates sludge that is collected through the different phases of this process. This matter and its biological reactions are reused for different purposes. On the one hand, when stabilized and extracted, this sludge produces biogases that are used as energy, and even as biofuel for vehicles. On the other hand, the sludge itself generated is used as organic fertilizer, replacing in many cases chemical fertilizers that are harmful to the environment. Finally, the algae and other microorganisms that proliferate in the process are also used to generate biomass, among other uses.

This interesting video helps us to understand in detail this process of collecting and treating wastewater as well as the subsequent management of this waste.

Thus, with the treatment of the water that we discard every day, we not only contribute to returning to nature that resource so necessary for our daily life, but it also arrives in perfect condition so that it can contribute to the environmental balance that we need.

The treated water returns to the natural environment, but is also used in:

  • Urban uses: street cleaning, irrigation, sanitary uses, etc.
  • Industrial uses: for example for the cooling of machines.
  • Agricultural and livestock use: cleaning, irrigation of crops, etc.
  • Other functions such as golf course irrigation, aquifer recharge, etc.

The largest treatment plants in the world

Atotonilco WWTP (Mexico)

It is the largest Wastewater Treatment Plant in the world, which treats all the waters of the Valley of Mexico destined to irrigate 80,000 hectares of land.

Stickney WWTP (Cicero, Illinois, United States)

Its 230 hectares of surface supply the entire city of Chicago and other areas and its water pumping station, lifts them from a system of tunnels to almost 100 meters deep

Bailonggang WWTP (Shanghai, China)

The main wastewater plant on the Asian continent with 24 hectares of surface, is responsible for the purification of a third of the waste that is dumped daily into the waters of the Yangtze River.

The importance of wastewater treatment

In summary, the Wastewater Treatment Stations contribute to reducing the waste generated. The recycling of wastewater minimizes waste, to which it is convenient to contribute with responsible use so that our future generations can continue to have the water resources necessary for life.

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The water footprint and environmental impact

Water is one of the most important resources for the survival of living beings, not only as a basic good, but also as a raw material or auxiliary element to produce many goods and services. What impact does water use have and how to control it? The concept of “Water Footprint” responds to this and other questions about the sustainability of water use.

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Hydration and Health

We all know that when the heat hits it is very important to stay hydrated. High temperatures invite our body to ingest liquids to satisfy the loss that we suffer when the thermometers rise, with a clear signal such as thirst. But what other symptoms can we have with dehydration? And most importantly, how important is hydration to our health, both in summer and winter? Next, we will answer all these questions.

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Why is there so little drinking water?

Our planet is made up of three quarters of water. But, nevertheless, in the so-called Blue Planet the scarcity of water is an increasingly pressing problem. Know the causes.

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Washing dishes

What is the water supply system of a municipality like?

In our day to day we make use of numerous services and systems without asking ourselves how they are managed. But do we know what the water supply system we consume is like? In this post we will tell you briefly

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What water purification methods are there?

We already know some facts about the water problem in the world. On the one hand, we know that only a small percentage of the planet’s water is fresh (around 2.5%). In addition, it is estimated that of this percentage only 0.3% is on the surface in the form of rivers, lagoons or aquifers. And to this is added that most of these water reserves are so contaminated that they cannot be consumed directly.

The water purification systems are one of the solutions to alleviate the problem of lack of water, so in this post, we will know in depth all the details about this problem and its possible solutions.

Human activity as the basis of water pollution

Much of this water pollution comes from human activity, such as agriculture, livestock, industry, mining, poor management of urban solid waste (garbage) or urban wastewater discharged without adequate treatment.

We also commented in a previous post that the main pollutants that we can find in water can be classified into:

  1. Microorganisms: bacteria, viruses, protozoa, etc. (they cause diseases such as cholera, typhus, hepatitis, etc.)
  2. Inorganic: sulfates, sulfites, nitrates, phosphates, etc.
  3. Organic: hydrocarbons, phenols, cyanide, etc.
  4. Metals : chromium, nickel, iron, aluminum, lead, cadmium, mercury, etc.
  5. Emerging pollutants: medications, steroids, etc.

This great variety of pollutants that can be present in surface and groundwater makes their purification very complicated and expensive, since on many occasions specific treatments must be provided for each one of them.

Another additional difficulty is the fact that the composition of water pollutants can vary throughout the year. Thus, the origin can come from sporadic industrial discharges, rains in some hydrographic basins that carry certain types of substances, etc. For this reason, it is necessary to analyze the water periodically to know its composition, propose a suitable purification method and adjust it constantly.

But, what methods of water purification exist ? What degree of purity do they reach? When are one or the other applied? What advantages and disadvantages do they have?

Although these questions cannot be answered quickly or understood without a good scientific basis, as they are in fact the subject of specific professional courses and masters, we give you a few brief strokes that can clarify them.

Water purification and purification methods

Depending on the origin and state of the water, and depending on its final destination, various treatment stations or plants are used. Although we have observed that in different countries they receive slightly different names, most of the time they respond to these names and acronyms:

They are large facilities that collect water from relatively clean rivers, lakes or aquifers. Through physical processes (such as decantation or filtration) and chemical (such as the addition of reagents to cause flocculation, chlorination, etc.) they make the water drinkable, preparing it for consumption.

Its main characteristic is that it is composed of a large number of round or rectangular pools through which the water passes. During this journey, they are removing or reducing the concentration of each of the pollutants that it can bring. They are very expensive and are designed to supply large and medium-sized populations.


Although not all these plants achieve an optimal level of purity, it can be said that they are the ones that leave water more suitable for human consumption.

These facilities take urban or industrial wastewater and treat it enough to be able to discharge it into rivers, lakes or seas. In this way they still contain contaminants, but less than before their treatment.
In its process, physical methods are also used: sandblasting, roughing or removal of solids such as paper or wet wipes, sedimentation, degreasing, etc .; chemicals, also by adding chemical products to cause flocculation, oxidation or absorption of the main pollutants; and biological. The latter consists of the passage of water through pools or beds where there are certain bacteria and microorganisms that feed on biodegradable organic substances.
Its size and cost depend on the volume and condition of the water to be treated and the existing regulations. This regulation establishes the degree of purification necessary before its discharge. Thus, stations of this type can be very large and expensive, or relatively small and more affordable.

They carry out a subsequent and additional treatment to the WWTP or WWTP. With it, it is possible to reuse the regenerated waters, instead of dumping them into nearby rivers, lakes or seas. This tertiary treatment usually consists of using disinfectants to reduce the concentration of microorganisms.

Reclaimed water is normally used for irrigation of parks and gardens, or for some industrial applications.


It is a physical-chemical process that basically consists of passing water at a very high pressure through a semi-permeable membrane. This membrane ensures that the water that manages to cross it leaves behind salts, molecules, etc. In this way, it is ready for use, normally after chlorination processes, etc.
For years they have been used mainly for the desalination of sea water. However, many of the desalination plants have been closed due to their high energy cost and the high pollution they cause. The current of water that cannot cross the membrane drags a higher concentration of pollutants that deplete underwater life wherever it is discharged. In addition, it wastes large volumes of water.
The water obtained with this method is of an acceptable quality for general use. However, its chemical qualities (absence of beneficial mineral salts for the body) and organoleptic qualities (mainly flavor) mean that most users do not consider it suitable to be drunk.

Water purification: a vital challenge

In summary, there are various industrial means for the water purification . Its use depends on various parameters, such as volume, origin, destination, available budget, etc. Furthermore, they are not fixed treatments, but rather allow a greater or lesser degree of purification.

In future posts we will deal with each of these plants or stations in more detail, as they are of great interest to know the type of water we consume and the environmental impact of its use.

As we have already commented, the treatment of surface waters allows to have large volumes of water, but they are usually expensive and complex methods due to the large amount of possible pollutants present in them.

The main advantage of Rain of Life atmospheric water generators is that they start from a very homogeneous water (the condensation water of the humidity of the air is practically the same anywhere in the world and at any time of the year) and without pollutants. Therefore, after the appropriate purification process in which, for example, beneficial mineral salts are added to the body, it is optimal for drinking and cooking.

In this way, RoL generators coexist perfectly with others Water treatment systems , such as ETAP, PTAP or reverse osmosis. These systems offer large volumes of water but on many occasions of a clearly insufficient quality for human intake.

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Taking care of water: one of # Water2me’s commitments

Taking care of water is one of the objectives of # Water2me, a United Nations ‘s campaign to raise awareness about the importance of water.

Water Day

The Water Day organized by the United Nations is celebrated every March 22. It is an initiative that seeks to raise awareness about the importance of this essential element for life. Although the surface of our planet has more than 70% of surface covered with water, only a very small percentage is fresh water.

More specifically, reference is made to 0.025% of that total is drinking water, which shows that taking care of it is an important commitment that must be faced as humanity. This covers not only the future, but also the present, as a mismanagement of this resource will result in unequal access to the liquid.

The problem of water scarcity

Water scarcity is one of the most important problems of humanity. This is a major crisis, as it involves a problem of the inappropriate use of the different sources found throughout the planet, one of the causes of which is the lack of awareness about the use of this liquid.

The demand for the different water sources accelerated thanks to the growth of the world population. This means that, per person, in developed countries an average of approximately 300 liters of Water up to date. However, in less developed countries this amount decreases to an average of 100 liters of water per day. Without a doubt, water, although it must satisfy the demand of the population, also generates strong inequalities throughout the planet.

If there are regions that have high concentrations of water, others lack it. For example, by 2025, 26 African countries are expected to have access to this essential resource for life.

Furthermore, not having equitable access to safe drinking water can cause the death of more than 4,500 children per day around the world, especially in the poorest regions.

Therefore, an environmental responsibility must be acquired, knowing that every action has its consequence and we must take care of it. In fact, awareness about saving water should be considered one of the priorities of our day to day.

Access to drinking water

According to the United Nations, some 2,200 million people (28% of the world’s population) do not have an absolute guarantee of access to drinking water directly.

This means that they must obtain what they need to survive through different mechanisms, such as community wells, where thousands of families must travel long distances to fill tanks or buckets.

The fact that people cannot access equitably to this natural resource means that, sometimes, they must prioritize its use. For example, it has been seen that in the most remote tribes of Africa there are many people who decide not to bathe frequently to have water to hydrate.

Although most readers will have access to this natural resource without any effort, just by turning on the tap and paying for the service, the truth is that in all parts of the world this situation is not the same. Although there are regions where there are rivers in good condition and flows where it reaches different populations, there are others where droughts can be a problem.

Appeal to sustainability

This campaign organized by the United Nations seeks appeal to sustainability in the short, medium and long term. While there are efforts by states and businesses to implement measures that can help solve this problem and guarantee access to the entire planet, consumers must take action on their own.

In that sense, some actions that involve a conscious use of this vital liquid should be implemented. Here are some essential ideas that can be put into action:

  • Close the tap when not in use . This applies to different daily actions: brushing teeth, showering, washing dishes, etc. Sometimes, we let the liquid run while we do another action, but this is completely harmful, since we can waste many liters.
  • Rationalize irrigation , for example, installing drip irrigation.
  • Avoid small losses . By that, it refers to all leaky pipes or faucets. They may look like tiny droplets, but accumulated, they can be large amounts of wasted water.
  • Use more efficient appliances , such as state-of-the-art washing machines and dishwashers with savings programs.
  • Install thermostatic or electronic faucet in kitchen and bathrooms.
  • Place aerators or flow reducers in the taps, which achieve great water savings.

Should the majority of the population take these sustainable measures, large changes in water availability , which would allow a more optimistic future to avoid scarcity and inequality.

Rain of Life atmospheric generators are a simple and modular solution to the lack of drinking water, as they guarantee the availability of several liters per person per day of excellent quality water, ideal for drinking and cooking.

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The benefits of using rainwater: in search of balance

Natural resources have always been a source of inspiration for our ancestors who lived finding alternatives to the lack of technology or developments to survive.

Currently there are indigenous populations that even continue to use ancestral systems of natural resource management for their day to day. The use of rainwater is one of the most versatile and ecological actions that the environment offers us and that little by little we forget to put into practice.

Water and Life.

Water is the most important natural resource for any living being. It is the vital element that ensures the development of biological processes necessary for the proliferation of life on our planet. A valuable resource, necessary, but not always given the importance it deserves. It is a staple good that constitutes more than 80% of most living organisms and that plays a leading role in mechanisms such as photosynthesis, essential for the balance of the ecosystem.

Despite knowing all these details, human beings have for years lost the perspective of their true dependence on this vital element, becoming a mere consumer product.

Now we realize again that, without water, there is no life.

How much water do we need?

Although there are variations in water consumption depending on geographical locations, on average the human being consumes 1.5 liters of water per day. In addition, to cook we need between 6 and 8 liters and for other necessities (personal hygiene, washing machines, washing dishes, etc.) each person has been consuming more than 170 liters of water daily.

Rainwater: the gift from heaven

Our ancestors were already clear that rain was a gift and as such they used it for different uses: cleaning, sewage, etc. Collecting rainwater was an integrated process in the life of human beings throughout our planet, since with it solutions were sought on a day-to-day basis. Washing, watering and even personal hygiene were the destination of those drops that accumulated in more or less archaic tanks for the collection of that water. Cisterns from the Arab world are the forerunners of current rainwater storage systems. These, in turn, descend from the monumental cisterns that were built in the Roman Empire to deposit that rainwater, which would later be used in agriculture and other uses.

The ancient Mayans, for their part, had their chultunes, their own cisterns in which they kept both water and corn and were built as underground chambers.

Industrialization gradually began to cause adverse effects on the quality of rainwater, being detrimental to human consumption due to its content of polluting elements harmful to health.

Most of the planet’s waters have physical-chemical and bacteriological pollutants that prevent their direct intake. Surface and underground water sources that were reliable yesterday are now heavily polluted:

  • Fertilizers used in agriculture,
  • Over-exploitation of livestock,
  • Irregular mining,
  • Lack of purification of urban, industrial wastewater, etc.
  • There are various means of purifying water, after which the water can be used for personal hygiene, but in many cases not for drinking and cooking.

The current purification systems mean that we can even treat that rainwater to consume it with all the guarantees.

rain water

Collecting rainwater: a wise decision.

The scarcity of water due to global warming is a reality, and that is why taking advantage of natural resources in a sustainable way is the guarantee for the future of our planet.

That is why collecting rainwater for domestic use is an interesting option, especially when we use it for irrigation. The stored rainwater does not contain chemicals or other elements that are harmful to plants. Similarly, its use in sewerage systems reduces the carbon footprint helping us to care for the environment.

Rainwater is practically distilled water, but without the minerals that are necessary for us. In addition, when we store it, it can become contaminated if, for example, the tank is not perfectly clean. To make rainwater drinkable, we must have adequate equipment that allows us to eliminate impurities and also provide that water with the necessary minerals so that it is totally suitable for our consumption.

That is why Rain of Life has developed equipment that performs the function of collecting rainwater, which is stored in a tank, keeping it in perfect condition until it is purified and consumed. In this way, both in homes or small businesses and in larger offices and schools, the RoL50 and RoL1.000 atmospheric water generators can be located with their solar kits that carry out the channeling and purification of the collected rainwater.