Swimmers in the United States who took a dip in pools last year may have inadvertently been wading in poo, a revelation that sent ripples of disgust through swimmers here.
Nearly six in 10 pools tested in a study by the Centres for Disease Control and Prevention in the US were found to be contaminated with the Escherichia coli, or E. coli, bacteria, an indication that human faeces had made its way into the water.
Although only pools in Atlanta were surveyed, the report stated that results were likely to apply across the country. Pools here, however, have been given a clean bill of health.
The National Environment Agency (NEA), replying to questions from The Sunday Times, said no swimming pool water has been found to be contaminated with E. coli, which can cause diarrhoea, in the past three years.
Still, the US findings were viewed with some concern here.
Swimming is one of the most popular sports in Singapore, and it is reflected in the growing number of pool licences.
In 2010, there were around 1,600 swimming pools run by the Singapore Sports Council (SSC), hotels, condominiums and private clubs. By last year, there were nearly 1,900.
Going by a Sunday Times poll of 45 swimmers, parents and coaches, cases of defecation in pools are not unheard of, though they are rare.
Mr Alvin Lee, a swimming coach with 14 years of experience, said he has seen stool at the bottom of training pools where children swim.
Such incidents are usually accidents since children are less able to control themselves, said another coach, Mr Lim Kim Seng, 62. He added kids sometimes use diapers which can leak.
Cleaning a pool of stool, however, is not as simple as scooping out the offending material.
Freelance pool cleaner Chris Rajoo Jayakrishnan has been in the industry for 30 years. He said that a pool has to be closed for at least six hours when faeces is found.
"We have to add soda ash, chlorine and acid, which will kill the germs. It will take about an hour. Then we let the water run," he explained.
NEA imposes a stringent system of checks to ensure hygiene. At least once a month, pool water has to be tested by laboratories for chemical and bacteriological quality.
The agency also conducts spot checks to make sure regulations are followed. Pool operators can be fined up to $2,000 for each transgression.
The SSC, which runs 25 swimming complexes, performs a daily regimen of vacuuming, chlorination and filtration before opening pools to the public.
At least once a week, pool decks and walls are also jet washed.
Describing cases of swimmers defecating in pools as "anti-social unhygienic acts", Mr Andy Tan, senior director for sports and recreation centres at SSC, said the council would refer perpetrators to the relevant authorities.
But such incidents were "very rare", he added.
Swimmers interviewed agreed, with most saying that the most unhygienic thing they have seen swimmers do is spit into the water.
Others complained of those who jump in without showering to wash off the sweat or tanning oil residue on their body.
Showering can reduce the impurities typically found on bodies, such as stool residue, which a swimmer could otherwise bring into the pool, said Dr Ling Moi Lin, director of infection control at the Singapore General Hospital.
It also cuts the risk of waterborne illnesses like diarrhoea and skin infections.
When The Sunday Times visited the Toa Payoh Swimming Complex on a weekday evening, only 15 out of 53 swimmers, in the space of an hour, were seen taking a shower before going into the pool.
But most swimmers interviewed felt the chemicals in the pool would kill any germs.
University student Yee Kai Ming, 27, said: "Sometimes the water gushes into my mouth and I have to spit it out, but I try to do it in the drain. I think it's OK, because the chemicals in the pool will clean the water."