Having an essential resource such as drinking water “at hand” has become a given for people and economic operators in industrialised countries. But the apparent simplicity is, perhaps, inversely proportional to the complexity that lies upstream. It is thanks to extraordinary technological and scientific advances, established over decades, that millions of people around the world are now able to safely consume water.


However, this facility raises questions as to the sustainability of this resource. It is a scientific truism that there is a shortage of fresh water as a natural element and increasing pressure on water resources. There is therefore a growing need to restore this element to nature after use and treatment, using sophisticated technological means, whether in a social or industrial context. This is the only way to offset the direct extraction of this element from nature, which, despite involving a long, time-consuming and complex cycle, ensures the sustainability of something so essential to life. 


Despite the extraordinary progress in this regard, there is a long way to go in order to guarantee universal access. Looking at current data, according to UNICEF and WHO, there are more than 2.2 million people, i.e., more than a quarter of the world's population, who still do not have access to purified water. It is therefore far from being a benefit for all.


The importance of this topic led the UN to recognise water as a human right in 2010, irrespective of social, economic or cultural status, gender or ethnicity. Reinforcing this initiative, as part of the establishment of the Sustainable Development Goals, the organisation adopted the aim of “Ensuring the availability and sustainable management of drinking water and sanitation for all”, to be fulfilled by 2030.

Water treatment is a complex process that involves various steps. Like many other achievements with a major impact on society, this one was also achieved by the need to find solutions to significant social dysfunctions that occurred at certain times in history.


Thus, it was due to the observation that the ingestion of water without any type of treatment was directly related to a higher incidence of diseases such as diarrhoea, typhoid fever, hepatitis A, leptospirosis, cholera and intestinal infections, in relation to which important measures have been taken over recent centuries.


The first documented methods of treating water were observed in articles written by the Greeks, around 2000 BC, which suggested heating water by boiling it over a fire, heating it in the sun, or even using a piece of red-hot iron dipped into a container with water inside. The basic principles that were used for centuries by various peoples to improve water quality were conceived here.


In Rome, in the first century BC, the first steps were taken in the distribution of treated water to the population. If the “drink” was vital for the men, then it was necessary to send it clean to the houses and public fountains, where the most disadvantaged used buckets to collect water. This is how they began to worry about the quality of the pipes, favouring those made of ceramics rather than lead. It was also the Romans, a few centuries later, who would build the first aqueducts, which represented a great advance in terms of distribution.


In the middle of the final phase of the Industrial Revolution, the first large-scale water treatment was carried out in London, in 1829, and included a filtering system, with sand, to collect water from the River Thames.

Attention to water quality was redoubled when it was confirmed, in the mid-nineteenth century, that it transmitted cholera. Treatment became mandatory in many cities through the addition of chlorine, a key chemical element for ensuring the suitability of water for human consumption and thanks to which it has been possible to save millions of lives. 

The water used on a daily basis and obtained through the supply networks comes from surface collection in large lakes or dams, or deep water, through aquifers. It is subsequently sent to Water Treatment Plants (WTP), where it undergoes a complex treatment process that makes it potable and “consumable” for people or for the widest range of economic activities, by correcting its physical, chemical and bacteriological characteristics. Today, the process is heavily digitised and is even controlled using artificial intelligence.


The initial phase is called screening, during which the existing impurities are removed, namely tree leaves, branches, suspended matter, sand and microorganisms.


This is followed by flocculation and decanting. At this stage, a reagent is applied, which will promote the formation of flocs through the aggregation of residues that are still present in the water. Due to their weight, volume and consistency, these flocs are deposited at the bottom of the tanks by gravity. Decanting then takes place, the resulting solids being subjected to a thickening and dehydration process before final disposal in a sanitary landfill.


The remaining water, known as clarified water, is transferred to the next treatment stage, which is filtration, which retains smaller solid particles. Today there are various technologies for this purpose, namely Reverse Osmosis, Ultrafiltration, Multimedia Filtration, Activated Carbon, among others, about which you can find out more here.


Finally, disinfection takes place to eliminate microorganisms (bacteria) that could be harmful to human health, namely using chlorine.

As a result of the growing environmental awareness witnessed in recent decades, ways have also been established of treating wastewater, whether resulting from use by populations or from industrial processes, driving companies and public entities to make large investments for the common good.


Wastewater is collected and sent to Wastewater Treatment Plants (WWTP). Depending on their origin and purpose, they are subject to different types of treatment and may, in particular and more demanding situations, also be disinfected.


After being treated at the WWTP, part of this water is reused for watering or washing public spaces or is returned to nature under environmentally safe conditions. The objective is to ensure the replacement of water in water resources without compromising public health and ecosystems, protecting nature and biodiversity.


With regard to the treatment of industrial process water, this is a specific field, and the technology employed depends on the industry and the type of pollution associated with it. It may involve biological depollution (in the livestock sector, for example), physical/chemical purification (chemical or pharmaceutical industry) or precipitation (metallurgy).

Bondalti, the largest Iberian producer of chlorine, has played a very important role in this area over the last few decades, through the production and supply of that chemical element, which is crucial for the success of these processes and which has a great positive social impact.


Reinforcing this connection to the water sector and its Iberian vocation, it recently created a business unit called Bondalti Water, made up of the companies Enkrott (of Portuguese origin) and AEMA (of Spanish origin), which have decades of experience in the treatment of water for the most diverse sectors. By developing and employing the most advanced technology available, they base many of their systems on the concept of circularity, promoting re-assimilation and reuse, with broad economic and environmental benefits.