Chlorination against bacteria, viruses and mould

The Covid-19 pandemic is making us all hyper-hygienic. But are chlorine-based products still the right choice for disinfection?

Thanks to the Covid-19 pandemic, we’re all a lot more conscious of the need to keep our domestic and workplace environments clean. It isn’t surprising; Covid-19 is a highly contagious and deadly disease, with an estimated fatality rate of between 0.5 – 1%.

Some organisations and companies are promoting chlorine as the disinfectant of choice for surface disinfection in our homes and workplaces. More recently, chlorine is being promoted as the ideal legionella control disinfectant for buildings opening up again after lockdown.

But how sensible is this? Let’s take a closer look at chlorine.

All About Chlorine

Chlorine was first discovered by Karl Scheele in 1774. Its introduction into water in the early 1900s has virtually eliminated the threat of water borne diseases such as typhoid and cholera from Europe and the United States since that time. Arguably water chlorination is one of the greatest public health achievements of the 20th century. Almost all UK water supplies are disinfected using chlorine.

When added to water, chlorine forms several by-products, as many as 700 depending on which water is being analysed. Chlorine is very reactive and reacts with the low level or organic materials found in almost every water supply. The most common are tri halo methanes (THM’s).

Many of these by-products are carcinogenic, toxic, or both. They are present in our drinking water at trace levels only, but they can still present a health risk to certain individuals. The World Health Organisation (WHO) indicates that the risk to health from chlorine by-products is extremely small in comparison with the risks associated with inadequate disinfection.

Chlorine risks: toxic and carcinogenic by-products

While there is a recognised risk, it isn’t often talked about. This will always be the case where large companies have a vested interest in preserving the use of a chemical. Water treatment companies across the globe are quick to minimise the risk associated with the use of chlorine.

There have been countless studies on the effect of chlorination by-products. Some of these studies were based on the observed effect on real populations, while others were laboratory-based studies on the by-products formed and their likely effect on people.

These studies seem to indicate that chlorine by-products in water are responsible for between 5% and 8% of all bowel cancers across the world. There are indications that they may be responsible for other cancers, particularly rectal cancer. Some papers offer compelling evidence, but the science is still insufficient to offer certainty – something that seems inconceivable for research into a chemical invented in 1774.

New toxic chlorine by-products are still being discovered

Researchers at Johns Hopkins University in the United States have recently discovered two new chlorine by-products. These products 2- Butene -1,4 Diol (BDA) and Chloro-2 – Butene 1,4 Diol (BDA + chlorine).

Corden Prasse, the leader of the study, states: “There’s no doubt that chlorine is beneficial; chlorination has saved millions of lives worldwide from diseases such as typhoid and cholera since its arrival in the early 20th century.

“But that process of killing potentially fatal bacteria and viruses comes with unintended consequences. The discovery of these previously unknown, highly toxic by-products raises the question of how much chlorination is really necessary.”

Electrochlorination is being used to replace bleach in certain situations. The chlorine and associated products produced by electrolysis of salt produces different and, according to some sources, even more toxic by-products than chemical addition.

Do We Really Need Chlorine in Our Drinking Water?

It is possible to have a potable water supply that does not contain any chemicals. For instance, Amsterdam’s water supply meets EU potable water standards but contains no chemicals. The cost of plant to achieve this is high so it is unlikely that chlorine will be removed from UK potable water any time soon.

Chlorine is, of course, the chemical of choice for building water disinfection. It is recommended in both BS 6700 and HSG274 Part 2, where the reaction of 50 ppm chlorine with localised biofilm could generate excessively high chlorine by-products.

Unfortunately, as well as reacting with water, chlorine also reacts with the biofilm that forms inside water pipes to form even more toxic by-products. More importantly, the chlorine is used up as it reacts with the organic material, so it cannot remove or even penetrate the biofilm.

It’s what makes chlorine such a poor choice of disinfectant for building water services.

Replacing chlorine as a water disinfectant

Around 40 years ago, a man named Hans Hungerbach started a project designed to produce a biocide to replace chlorine as a water disinfectant. The chemical produced was Huwa-San (HUngerbach WAter SANitiser). It is the most stable silver-stabilised hydrogen peroxide in water, because it is designed to mitigate the reaction between chloride in the water and the silver ion.

The invention of silver-stabilised hydrogen peroxide means that building water services no longer need to rely on chlorine for protection against legionella and other bacteria, viruses and mould. Huwa-San is much more effective at disinfecting water and removing the biofilm inside water pipes.

Before we set up SafeSol, we spent years using chlorine and chlorine dioxide in our roles in the public and private sector. We have made a conscious decision not to promote chlorine-based disinfectants… because we know that silver-stabilised hydrogen peroxide is a much more effective and safer option in almost all circumstances.

SafeSol have worked with Huwa-San for over 20 years and have more than 75 years experience in water treatement. We are happy to help with any queries and provide technical support .

Call 0191 4478008 or