NEA monitoring E. coli at Sentosa beaches; the bacteria is usually freshwater, not marine, quality marker, Singapore News

AsiaOne

17-07-2025

SINGAPORE — The National Environment Agency (NEA) has started monitoring levels of Escherichia coli (E. coli) at Sentosa's beaches, following news that swimming events at the World Aquatics Championships were twice delayed due to elevated levels of the bacteria in the waters.
NEA does not usually assess marine water quality based on E. coli levels.
Instead, it follows World Health Organisation (WHO) guidelines to determine the suitability of a recreational beach for primary contact activities, by measuring the levels of another group of bacteria, Enterococcus.
In response to queries from The Straits Times, NEA said that WHO recommends using only Enterococcus for assessing marine water quality. Epidemiological studies have shown a strong correlation between Enterococcus levels in marine waters and public health risks.
NEA said that its weekly water monitoring showed that the water quality at Sentosa beaches has been in the "normal" range in the past few weeks.
The recreational beaches are also graded every six months based on the past 100 samples. NEA said that the Sentosa beaches were graded "good" in the latest grading exercise in January 2025, and suitable for swimming and other primary contact activities.
While most strains are harmless, some can cause serious illnesses such as diarrhoea, urinary tract infections, pneumonia and sepsis.
Meanwhile, Enterococcus is another group of bacteria - also naturally found in the intestines of animals and humans - which can also cause urinary tract infections and gall bladder infections.
It can also sometimes be found in soil, water and plants. The bacteria can also survive longer in marine environments.
ST previously reported that World Aquatics adopts stricter water quality standards compared to guidelines set for recreational swimming, given the prolonged exposure faced by athletes during competition, with 10km races typically lasting around two hours.
The men and women's races were later again pushed to 1pm and 4pm respectively on July 16 as the results from a sample taken on Tuesday (July 15) morning showed that the levels are still above "acceptable thresholds" despite improvement.
The next open water swimming events are men and women's 5km races scheduled for July 18.
World Aquatics had said that regular water quality monitoring and testing continues throughout the competition period to ensure athlete safety, with the health and safety of all participants continuing to guide all competition-related decisions.
Associate Professor Yann Boucher, co-director for the climate, environment and health programme at NUS Saw Swee Hock School of Public Health, said that athletes are more at risk as the strenuous exercise can lead to swallowing more water as compared with recreational swimming.
"The length of time spent in the water can also contribute as the risk is proportional to how much water is swallowed," he added.
Experts said that potential sources could vary from animals and humans to wastewater discharge.
Professor Boucher said that the bacteria can come from various sources such as birds, humans swimming, wastewater leakage or discharge - which he said is often linked to the systems being overwhelmed by heavy downpours.
Professor Paul Tambyah, past president of the International Society for Infectious Diseases, said that it could also come from boats which are not properly disposing of human or animal waste.
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This article was first published in The Straits Times . Permission required for reproduction.