The arrival of cholera in Portugal in 1833 killed 40,000 people - causing more casualties than the civil war being fought at the time, between liberals and absolutists. The bacterium had entered Europe only one year earlier, brought from the River Ganges, in India, via trade routes. In 1832 alone, it caused 20,000 deaths in Paris, and over 6,500 in London. And this first wave was followed by eight more epidemic waves, which were greatly exacerbated by the consumption of contaminated water and fresh produce, the concentration of infected people in confined spaces and a general lack of hygiene.


The last cholera epidemic broke out in 1974 in Tavira. According to the Expresso weekly newspaper, over 1,000 cases were recorded - in particular in Lisbon and in Porto. The precautions recommended at the time did not differ very much from the advice given during the current Covid-19 pandemic: the redoubling of hygiene standards, in particular hand washing; quarantine and isolation of high-risk groups. And in the case of cholera, of course, the disinfection of fresh foodstuffs and the boiling of drinking water.

Chemistry found the right response to combat outbreaks of cholera, whether on a local or an epidemic scale. And the solution found was Chlorine. Its sanitising potential was discovered during a typhoid epidemic in England at the end of the nineteenth century. But it was from 1902, in Belgium, that its application became common practice and, from then on, it spread around the world.

Chlorine possesses a strong residual potential, which guarantees that, after treatment, water remains drinkable until it is consumed. Even though there are problems involving the sanitation of contaminated pipelines or containers. This advantage, which offers additional protection to consumers, is coupled with the fact that the treatment of water with chlorine is cheap and easy to apply. 


The treatment of water with Chlorine and its by-products has not only helped to combat cholera. It has brought other benefits. One is that Chlorine has the potential to eliminate all pathogenic agents that my exist in water, whether germs, bacteria or viruses. As a result, its use has helped greatly in the reduction of infections such as typhoid fever, dengue fever, Ebola, legionella, leptospirosis and various types of hepatitis or gastroenteritis. In the case of typhoid, an epidemic disease, the treatment of water with Chlorine was a decisive step towards its eradication from Europe and many other regions of the globe.

However, the water that flows from the taps in our homes is not the only water purified with Chlorine. This chemical element is also used in the treatment of water used for recreational purposes or sports, such as swimming pools, and at waste water treatment plants. Its use is also common in the treatment of water for industrial use and for refrigeration. 


In Portugal, the Chlorine and Hypochlorite used in the drinking water we consume in our homes and in the purification of water used for recreational and industrial use is produced by Bondalti, at the Estarreja Chemical Plant, using the best available technologies. This guarantees environmentally responsible production with high standards of Safety and Quality.

Chemistry - and the constant development of scientific knowledge - has been decisive in combating diseases that have plagued Humanity for thousands of years. Just as it is proving useful in the current Covid-19 pandemic: the clearest proof of this is the Chlorine and Hypochlorite that is being used around the globe to disinfect streets and surfaces!