Bermuda’s beaches are safe for swimmers, Government said last night.

And Minister of Health and Environment Trevor Moniz said that periods of contamination on the south shore of the Island involved limited areas, lasted for short periods and only happened under specific weather conditions.

Mr Moniz went on the defensive after the US Consulate in Bermuda issued a warning to its citizens about water quality off the Island’s beaches — which might cause infections and gastroenteritis.

The warning notice also said Americans might want to consider Hepatitis A and typhoid immunisation before swimming in Bermuda’s waters.

The advisory came after a study last year by the University of Laval in Canada, the Bermuda Institute of Oceanic Studies (BIOS) and Government departments of the waters around Bermuda, which found evidence of high levels of contamination from sewage under certain weather conditions.

But last night Mr Moniz played down health concerns, saying: “Research has demonstrated that once these circumstances change, the water completely corrects itself within hours.”

He added that the Department of Health had set up an automatic weather notification system, which alerts staff when wind and weather conditions combine to increase contamination risks.

And he said that a survey of the causes of food and waterborne infections that cause gastroenteritis carried out in 2011-12 “ultimately found that people were not at risk of gastroenteritis from swimming”.

Environmental health staff monitor Bermuda beaches and take water samples for quality testing twice at week at major beaches and around the Hungry Bay sewage outfall and nearby Grape Bay in Paget.

A statement by the Ministry said: “The results of these samples continue to meet the US standards for acceptable bathing water quality.”

The four page statement, issued last night, added that “greaseballs” had been washed ashore in July, April and May of this year, when the winds were easterly and swells brought grease onshore from the sewage outfall.

But the statement promised: “The Bermuda Government will notify the public if there is another situation of this nature in the future.”

It added that environmental health officials and the Corporation of Hamilton had met restaurants in a bid to improve grease traps and grease management in kitchens.

The statement added that extra investment in the treatment of sewage at the Tynes Bay plant would improve the handling of waste, while the King Edward VII Memorial Hospital would have a new sewage treatment plant this year, which would help cope with the 500,000 gallons of waste a day produced by the City of Hamilton.

Improvements will also this year be made at the Bermuda Land Development Corporation’s sewage treatment plant, which is pumped out to sea around 1km off Clearwater, while the Dockyard sewage treatment plant, which delivers waste to a borehole, will soon treat sewage from Boaz Island as well.

The statement added: “While we understand the US Consulate desires to protect its citizens, we have to reiterate that bathing in Bermuda’s waters does not pose a health issue.”

Stuart Hayward, chairman of environmental campaign group BEST, said: “This is a situation where we’re caught between the devil and the deep blue sea, somewhat literally.”

But he added that weather conditions that lead to pollution problems from the Seabright sewage outfall were “not common” and that, to the best of his knowledge, “sewage-related diseases have occurred rarely, if ever”.

Mr Hayward pointed out that Bermuda was the most densely populated ocean island on earth and that waste management would continue to be a problem.

And he said that Bermuda would have to look at the “carrying capacity” of the Island and how many people it could support without environmental damage.

Mr Hayward added: “Sure, we could wish that the message had been a little softer, a little kinder. We could also wish that our waste policymakers had done a little more, a little sooner.

“But we can’t make the results of the study disappear. Neither can we fault the US Consul’s discharge of his duty to his homeland’s citizens.

“The best we can hope for is rapid movement to further improve the way we handle sewage, followed by some reflection of that improvement in an updated message from the Consul General to his fellow Americans.”

Deputy Governor Ginny Ferson added: “It is the responsibility of consular staff across the world to provide travel advice to nationals visiting the country in which they are based.

“This may from time to time include health and safety factors such as water quality issues.

“However, it is also worth bearing in mind that the report which is cited makes clear — and the US Consulate General’s bulletin acknowledges — that the problems with water quality arise only in certain places and for relatively short periods.

“For much the greater part of the Island’s shoreline and the vast majority of the time, Bermuda is a great and safe place for all kinds of water sports, including swimming and diving.”