Some filters could pose health risks, expert warns

When most of us think about safe water, we think of “clean” and base that on the superficial metrics of the water being clear and odourless, but water safety is more than what you see.

According to water treatment professional and Crosslink Aquatic managing director Alex Goh, clear water does not necessarily mean healthy water due to something less visible: Chemical byproducts that form during water treatment.

Speaking to theSun, Goh explained that public water systems treat raw water so that it does not carry diseases, with chlorine being the go-to disinfectant for a long time.

“To deal with the issue of bacteria, chlorine began to be added to treated water,” he said, referring to how chlorine would kill harmful bacteria and pathogens, which were responsible for causing major outbreaks of typhoid, cholera and diarrhoea early last century.

The wide adoption of chlorination is credited with saving countless lives, but there is an unfortunate catch, as Goh explained that cancer rates began to increase in the areas with chlorine in the water.

“Cancer rates began to shoot up in the areas with chlorine in the water, which led to research discovering that a byproduct of chlorine is trihalomethane”.

Why THM matters

Trihalomethane, or THM, is a disinfection byproduct and a chemical compound formed from the reaction between chlorine and organic matter in the water – such as decaying leaves or insect carcasses. Not only is THM colourless, odourless and invisible in the glass, Goh pointed out that the compound is also carcinogenic.

That sounds alarming but according to Goh, it is expected, as municipal water treatment plants are duty-bound to comply with the World Health Organisation’s (WHO) recommendations, where THM control is a primary concern.

“Fortunately, our tropical rainforest climate provides an abundance of fresh and surface water for raw water intake, keeping organic content relatively minimal. Combined with standard municipal treatment system design, proper operational control and thorough, frequent filter cleaning, the accumulation of organic matter is effectively minimised, thereby preventing the build-up of THM levels”.

However, Goh said, if households, shops and so on use filters that generate organic materials, the free chlorine may increase THM but users may not know it because it is not tested once it comes out the faucet.

“If the water is or looks a bit dirty, there are actually less carcinogens in it, but once filters make water much cleaner, they increase the carcinogen content. Your filter actually makes your water less healthy.

“The possibility of clear and odourless toxins present in the water are complicated, thus most consumers assume that the cleaner the water means healthier it should be,” he said.

How filters can make things worse

Goh also said he has seen businessmen capitalise on the misconception to profit off it, with the variety of single, dual, outdoor and indoor water filters, which he also claimed is unnecessary.

Instead, his advice is for consumers to be savvy with basic scientific knowledge and to make sure they do not install water filters that generate carcinogens such as THM.

“Certain water filters, particularly activated carbon media, are highly effective at removing chlorine and absorbing toxins, including disinfectant byproducts and other contaminants, provided they are properly designed and maintained. The carbon media must be adequately protected against premature exhaustion”.

However, Goh explained that once the carbon becomes oversaturated, it may begin to release or “vomit” previously captured contaminants back into the filtered water, resulting in the water still appearing clear but may now contain concentrated toxins that pose potential health risks.

“Water professionals often prefer the term ‘adsorb’ rather than ‘absorb’, because carbon binds contaminants onto its surface and stores them within its pores but this storage capacity is limited. Once the adsorption sites are fully occupied, the media can no longer retain additional toxins and may release accumulated contaminants on top of the original toxin load.

“Therefore, beyond removing existing contaminants, it is crucial to prevent unintentionally generating additional toxins that overload the carbon media beyond its designed capacity”.

Safe drinking water is not just about appearance. It is also about understanding what is in it and how treatment affects health. As Goh stressed, knowing the science helps you make smarter choices.

He also said that Malaysians should question whether the widespread installation of household water filters that are not maintained in accordance with proper standards, particularly the failure to ensure thorough and frequent cleaning, could be contributing to broader public health concerns.

“Malaysia has been reported as one of the countries with relatively high cancer risk rates. Within national statistics, Chinese Malaysians appear to record higher cancer incidence rates compared to other ethnic groups, despite being a minority population. At the same time, Chinese households are also widely known to have one of the highest adoption rates of household water filtration systems,” he noted.

Correlation certainly does not equal causation here – Goh admitted this is merely a speculative observation on his part based on publicly discussed statistics but one that is worth noting regardless.

“As of now, no formal scientific study has been done to conclusively verify a direct link between improperly maintained household water filters and cancer incidence rates. Further independent research would be required to establish any definitive connection,” he said.

For more information, please contact Goh, water treatment system design engineer, for free water services through WhatsApp at 017-3399533.

 The Sun Malaysia