POLLUTED waters off Pasir Ris beach could be caused by storm-water runoff, activities in rivers there, and indiscriminate discharges from industries and construction sites, said Environment and Water Resources Minister Yaacob Ibrahim.

Non-domestic activities in the open seas also cannot be ruled out, he added.

He said this in a written reply to Mr Charles Chong (Pasir Ris-Punggol GRC), who sought an update on the investigation into the cause of pollution there.

Last month, the National Environment Agency (NEA) declared the waters unsafe for swimming, because high levels of bacteria normally found in human and animal faeces were discovered.

But Dr Yaacob pointed out that the water quality had not deteriorated. Rather, Singapore had adopted a higher water-quality standard based on World Health Organisation guidelines.

The new guidelines require at least 95 per cent of the water samples to have enterococcus levels of below 200 counts per 100 ml, which Pasir Ris beach did not.

Dr Yaacob pointed out that the premises along Pasir Ris beach are also connected to sewers to ensure sewage is channelled to the used water network and properly treated.

NEA is undertaking a detailed consultancy study to better understand the specific sources of pollution affecting beachers here, and to determine if other measures can be adopted, he said. The study is expected to be completed early next year.