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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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