SINGAPORE - Members of the public have been advised against drinking water without treatment from the wells and taps on Pulau Ubin.

Recent findings show that the quality of water from wells used by retail food outlets at Pulau Ubin has deteriorated, said a joint press release on Monday (Dec 21) by the National Environment Agency (NEA), PUB, Singapore Land Authority, and National Parks Board.

The eateries are now required to use bottled water, PUB water from the mainland, or boil the water drawn from the wells for at least one minute continuously before using it to prepare food and drinks for sale, the statement said.

Pulau Ubin residents have been advised to do the same for water that they consume, or use to brush their teeth and wash crockery with.

There was an earlier advisory in March 2014 after unsatisfactory water samples were obtained from the taps of the retail food outlets, the statement said.

The Straits Times understands that the water quality has deteriorated progressively.

When asked about the cause of the decline in water quality, the agencies said: "There could be a few possible causes for the deterioration in the well water quality at Pulau Ubin. For example, the water may have been contaminated with animal or human waste or surface runoff from contaminated soil."

Many of Pulau Ubin's residents use well water for their daily needs.

There are signs put up in the public toilets reminding the public not to consume the water from the taps, as the water is drawn from wells and is thus not potable without further treatment.

More public signs will also be put up.