Team GB marathon swimmers in Paris will be vaccinated for typhoid and hepatitis A amid ongoing concern over water quality in the Seine, according to reports.

Approximately 1.4 billion euros (£1.2billion) are believed to have been spent to upgrade the French capital’s sewage system and water treatment capabilities ahead of the competition at this summer’s Olympic Games, which would see some of the first swimmers take to the river since the activity was banned due to health risks in 1923.

Team GB swimmer Hector Pardoe, a former Whitchurch and Ellesmere swimmer,  said: “We’re going to have a typhoid and hepatitis A vaccine beforehand and be on antibiotics after the race, regardless of what the water samples show.

“I haven’t had to take precautions like this before, but the last thing AquaticsGB wants to do is to put any of us in jeopardy, so they are being really cautious in the run-up to Paris.”

Triathlon swimming legs at both the Olympics and Paralympics are also scheduled to take place in the Seine, from which the Surfrider Foundation has been taking bimonthly samples for the last six months.

Of the 14 samples taken, its report said “only one enabled our team to conclude that the quality of the water in the Seine at this particular point was even satisfactory… it is therefore clear that the athletes who will be taking part in the Olympic and Paralympic events planned for the Seine will be swimming in polluted water and taking significant risks to their health.”

E coli can cause a range of serious infections and other side effects.

There remains a possibility that water testing during the Games could still force events to be postponed or, in a worst case, cancelled.

Paris 2024 president Tony Estanguet said: “When we decided to have this competition in the Seine we knew it will be a big challenge.

“We are still confident that the triathlon will be based in the Seine because we have contingency plans. We can postpone for rainy conditions. Because it’s programmed at the beginning of the Games we can wait for better conditions. So we are confident that it will be possible to use the Seine.

“We change the date and postpone from one day to three days until it’s OK. And there is a final decision where we could not swim – it’s part of the rules of the International Federation. It’s what we want to avoid, of course.”