Researchers are examining the risk posed to sea swimmers and surfers by antibiotic-resistant superbugs which could cause life-threatening infections.
A team at NUI Galway are exploring whether recreational waters are carrying potentially deadly bacteria that is not routinely tested for.
The deadly superbugs are recognised as one of the greatest threats to human health.
While Ireland has some of the cleanest bathing waters in Europe, raw sewage is still being discharged at more than 30 locations.
The Antimicrobial Resistance and Microbial Ecology Research Group at the university is launching the PIER study (Public Health Impact of Exposure to antibiotic Resistance in recreational waters), funded by the Environmental Protection Agency (EPA).
Researchers are hoping to recruit 300 people to take part - one group of 150 people who regularly use the sea, lakes or rivers for recreation, and a second group of 150 people who rarely take to the water.
A key part of the project is to understand how superbugs get into human populations to help scientists learn how to control the spread of antibiotic-resistant bacteria.
Previous research carried out by the team found potentially lethal bugs in seawater around Galway.
Dr Liam Burke, co-investigator on the PIER project, said some superbugs are very common in the environment because of increased antibiotic use in humans the release of sewage, manure and effluent containing antibiotics and antibiotic-resistant superbugs, which can end up in Ireland's lakes, rivers and seas.
"Although bathing waters are routinely tested for some bacteria, they are not tested for antibiotic-resistant bacteria, so we don't really know to what extent they are present," Dr Burke said.
"PIER will look into whether people who regularly use Irish waters for recreation are at risk of becoming colonised with superbugs."
Dr Burke also warned about the dangers of heavy rainfall and its impact on beaches and sea swimming. He said that drains can overflow and then carry wastewater into seawater and lakes, leading to no swim notices being issued, like those in Co Clare recently.
"If hospital waste ends up in the sea, it will more than likely contain antibiotic-resistant bacteria or a slurry stream from a farm ends up getting into the water or river, then there is potential for that to contain a high level of antibiotic-resistant bacteria," he added.