Given that Singapore’s tap water is one of the cleanest in the world, does this country need a water filter? Will they do more harm than good? Talking Point plans to investigate.

Singapore: From filter cloth filters priced at 30 cents each to S$100 water filter tanks, and even countertop systems worth thousands of dollars, the sales of water filters have been growing over the years.

Despite the fact that Singapore’s tap water is one of the cleanest in the world, the National Water Authority PUB conducts rigorous tests on samples from the source to the tap water to ensure that the water is always clean.

Proponents of water filters say the water is cleaner and healthier, with impurities removed and minerals added. The Water Filter and Alkaline Water Company also advertised a list ranging from improving gastrointestinal health to detoxification and even cancer prevention.

But can these claims stand the test? Can I remove substances such as chlorine and fluoride through a filter, and add minerals such as magnesium, zinc, and calcium to the water?

To find out, Talking Point plans to send two water samples collected from the same place-one from the tap and the other through a filter with a reverse osmosis mechanism-to the laboratory.

With the help of Raymond Ong, manager of SGS Testing and Control Services Laboratory, Talking Point host Steven Chia found that the concentration of chlorine remained constant at 0.1 milligrams per liter (mg/l).

However, the filtered water contains less fluoride: 0.1 mg/L, while the fluoride in tap water is 0.5 mg/L.

Ong pointed out that although this is indeed the case, the allowable level of fluoride in Singapore’s water is 0.7 mg/L. "As long as it does not exceed that, it is safe," he said.

As for the added minerals, the test found that the zinc content in the filtered water did not change significantly, while the magnesium content increased by 1 mg/L.

However, the calcium content increased from 13 mg/l in tap water to 1 mg/l.

"If we add up all three minerals observed in the report, the overall mineral content will actually decrease," Ong said. This means that the filter removes more minerals than added minerals.

What about marketing claims?

During the investigation, Talking Point also asked food scientists about the authenticity of several marketing campaigns. In particular, filtered water can improve gastrointestinal health, make it easier to be absorbed by the body and cure cancer.

For example, alkaline water is said to help neutralize stomach acid, says Leong Lai Peng, a senior lecturer in food science and technology at the National University of Singapore.

"The problem is that acid is used to help digestion. If you neutralize it, then it won't be digested anymore," she pointed out. "There is no reason anyone wants to neutralize the acid in the stomach."

As for the claim that the filtered water molecules are smaller and easier to absorb, she said that the size of the water molecules will not change, "regardless of whether they pass the filter or not."

"Water is water. There should be no difference between filtered water and ordinary tap water," she added. "Both can help you hydrate."

She also said that "there is no evidence" that filtered water can prevent cancer.

Nonetheless, she said that filtering water can benefit certain groups of people—for example, people with weakened immune systems and people undergoing cancer treatment—because some filters can filter out harmful bacteria and viruses.

In fact, although a water filter company contacted by CNA Insider stated that they received positive feedback on its products from customers suffering from diseases such as eczema, they pointed out that most of their customers did not buy them for medical reasons. The product.

Joel Lim, managing director of Ruhens, stated that his company does not focus on medical benefits because it believes that "purified water is the best."

"Through our filter, customers can drink pure water to remove rust, chlorine or other particles that may be present in the water," he said.

There are many types of water filters on the market, from simple water tanks to elaborate installations under the sink. However, in the end they boil down to two categories: those that remove pollutants from the water, and those that claim to change the water.

Watch: Can a water purifier really purify your water? (23:52)

There are two common types of filters in the latter category: ion exchange filters and alkaline filters.

Kwok Chen Ko, who runs a blog named Water Quality in Singapore, said that ion exchange filters can be used as "softeners" for hard water.

Hard water contains a lot of calcium and magnesium. The ion exchange resin of the filter captures these calcium and magnesium and releases soft water in the process.

This kind of soft water is valued by coffee lovers, who believe that lack of minerals can prevent the buildup of limescale from clogging the coffee machine.

On the other hand, alkaline filters convert water by passing current through the water. Many people think that the alkaline water produced is healthier.

In another category, filters that remove contaminants in the water use activated carbon, which is a common component in many filters.

However, as Guo pointed out, there is a problem: Over time, filters may allow bacteria to grow in them, and those with activated carbon are "especially worrying."

"It adsorbs organic matter and serves as food for bacteria," he said. "So we are talking about bacteria growing on the filter and entering the water."

A test conducted by Talking Point showed that filtered water may indeed be dirtier than tap water.

In the test, five households using filters provided two water samples: one from the faucet and the other through the filter. Although filters contain different types of filter media, they all contain activated carbon.

The results showed that the counts of bacteria in the tap water drawn from four of the households were below 500-a safety limit set by the Singapore Food Authority.

But when it comes to filtering water, the number of bacteria in the three households ranges from 9,000 to 25,400.

Guillaume Drillet, the SGS regional manager in charge of the test, pointed out that the filters used in the households with the highest bacterial counts were replaced one month after the deadline.

"The longer you let the filter run, the more likely it is that bacteria will re-grow," he said. "Therefore, it is very important to follow the schedule proposed by the manufacturer."

Chia's family also participated in the test. He changed the filter one month before the test, but even the water in the filter had 9,000 bacteria.

"Bacteria regenerate very fast. Therefore, once there are nutrients and the surface... a biofilm is formed," Drillet said.

"That's why, technically speaking, water from PUB is safer because there is control. The water you receive...has been treated with PUB and contains chlorine to prevent regeneration.

The filter may remove some of the chlorine and act as a place where bacteria can start to grow again.

Although the test was not conducted with filtered water from Ruhens, the company noted that bacteria can accumulate "almost anywhere", so it is important to ensure that the filter is replaced as planned.

Ruhens also stated that the use of a tankless water filter—the parts of which can be disassembled and cleaned—rather than storing the water in a tank after filtration can reduce the risk of bacterial growth.

Watch this episode of Talking Point here. The show is broadcast on Channel 5 every Thursday at 9.30pm.

Editor's note: After the company clarified, the reference to the Hydroflux managing director in an earlier version of this story has been deleted.

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