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What’s being done to clean swimming pools and what you can do, like showering

Singapore’s public pools are generally safe, but swimmers may take hygiene for granted as chlorine is used as a disinfectant. Even not showering before a dip can have a negative impact. The programme Talking Point dives in to investigate.

What’s being done to clean swimming pools and what you can do, like showering

What's in the pools can affect children as some are more susceptible to skin irritation than adults.

SINGAPORE: In 2019, there were more than 6.5 million visits to Singapore’s public swimming pools. In today’s post-COVID-19 world, the visitor figures are about 60 per cent of monthly capacity.

Some things have not changed, however; for instance, a number of people think it is acceptable not to shower before entering the pool, the programme Talking Point finds out in a series of vox pops.

Others may even pee in the pool, thinking that chlorine is used to disinfect the water.

The problem, however, is that urine and sweat contain ammonia, which reduces the effect that chlorine has on the water.

So what is being done to keep the pools sufficiently clean to protect swimmers from bacteria and viruses, which can enter the water? And what is the principal reason why one should shower before swimming?

WATCH: The real reason why you should shower before swimming (2:00)


Marchwood Laboratory Services technical manager Tan Thuan Piang, who has sampled Singapore’s pool waters with his team for over 15 years, noted that ammonia in pools, though mainly from sweat and urine, also comes from sunscreen lotion and cosmetics.

While the amount of ammonia in Singapore’s pools is usually “minute” — low enough to escape detection — a possible reason for this is that ammonia “reacts very fast” with chlorine in the water to form the by-product chloramine, he said.

When there is a “heavy chlorine smell”, it is usually tri-chloramine, a type of chloramine formed as the ammonia level rises and “not the chlorine we really want”, cited Nanyang Environment and Water Research Institute executive director Shane Snyder.

“It’s a nuisance,” said the professor, who has studied water quality and safety for more than 20 years. “As the chlorine forms chloramine, there’s less chlorine there. So we have to … add more chlorine to keep the level safe.

“If we don’t practise good hygiene, the amount of chlorine in a swimming pool will drop quickly and make it less safe … The more hygiene we have, the less ammonia there’ll be and the cleaner the pools stay.”

More visitors in pre-pandemic times, but hygiene matters as much today, if not more.

This is why he “always” advocates showering before entering the pool — to minimise the amount of chemicals it needs.


Chloramine can also have a more direct effect on swimmers.

National Skin Centre consultant dermatologist Lucinda Tan, who handles two to three patients a month for swimming-related conditions, said chloramines can “irritate and dry the skin” by stripping away the skin’s natural protective oil.

“This allows dust, bacteria (and) allergens to enter and cause irritation. A normal person with normal skin … may get away with that,” she said.

(For) a patient with eczema or very dry skin … what happens is that it becomes very itchy. The patients end up scratching badly.

“You break a lot of the skin barrier, and you allow a lot of germs to enter, and then you can get bad infections," she added.

“If your immune system is compromised … and (you have) a small cut and whatnot, you can still pick up an infection that can potentially worsen with time.”

She noted that all exposed parts of the body, including the hair and eyes, can be affected. People may also end up with a dry and itchy throat if they swallow “a little bit more” pool water.

And some children may be more susceptible to dry, irritating skin than adults.


To maintain safety, there are national standards for the chlorine level in Singapore’s swimming pools: It must be between one to three parts per million.

“Too little chlorine (and) it’d encourage algae to form. Too much chlorine (and) you’d feel the itch and discomfort on (your) skin,” said Jonas Su, operations director of pool maintenance company Anwill.

Normally, at the end of a servicing, his team adds chlorine even if the pool passes muster, as the reading would drop.

“By adding a little bit more, probably it’ll shoot up … still within the ideal range,” he said. “It’ll last for a few days before we come again.”

Standard pool maintenance includes using pool vacuums weekly to remove sediment on the floor.

Other parameters for testing pool cleanliness include the pH value, colour and turbidity (cloudiness) of the water.

By regulation, the pH value — which shows the level of acidity or alkalinity — should be between 7.2 and 7.8.

But when Talking Point submitted samples from 10 public pools — in Ang Mo Kio, Bedok, Bishan, Clementi, Jalan Besar, Jurong East, Kallang Basin, Queenstown, Tampines and Yishun — to Marchwood for testing, half of them were not within this range.

“It’s not a concern,” said Marchwood’s Tan, who described the readings of 8.1 to 8.3 as “slightly higher”. “But any pH that’s above nine will cause some skin irritation.”

Marchwood also tested the samples for faecal bacteria, namely E. coli and the coliform count.

By the National Environment Agency’s standards, there should not be more than 200 bacteria per millilitre of water. And all the samples met this standard as well as the other test parameters.

WATCH: Clean or not? We test 10 public swimming pools in Singapore (2:13)


Besides adding chlorine to pools, the cleaning process includes scooping up debris and vacuuming the bottom of the pools. This can be a laborious task.

What swimmers can do for personal hygiene on their part is relatively simple, however, like having a quick rinse before entering the pool to get rid of dirt, as well as applying moisturiser and sunblock if needed.

Although moisturisers would contribute to the formation of chloramine, Tan the dermatologist said their use would help buffer the effects of chlorine or chloramine on skin.

There are “two broad groups” of moisturisers: One has the “building blocks” of skin to repair the skin; the other acts as a protective barrier. “So it depends on a patient’s preference and the skin conditions,” she said.

“Generally, you’d want something slightly oilier because you want the moisturiser to last for the duration of the swim … The ones that are more water-resistant would help as well."

WATCH: The full episode — How clean are our public pools? (21:55)

She also recommended having a rinse immediately after leaving the pool to “get rid of all the chlorine”. She added: “If possible, use a gentle cleanser (for) a more complete removal.”

For extra assurance, swimmers can even get a test strip online that shows the pH and chlorine levels of the water on the spot.

Watch this episode of Talking Point here. The programme airs on Channel 5 every Thursday at 9.30pm.

Always shower before using the pool and preferably afterwards too.
Source: CNA/dp


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