Bacteria aren't the only microscopic organisms floating in the water that you want no part of. Viruses that can lead to a range of ear, eye, gastrointestinal and respiratory infections may also be floating all around you when you take a dip in the water.
A team of European researchers taking 1,410 samples from nine countries found the presence of viruses nearly 40 percent of the time. Adenoviruses, which can cause respiratory infections, ear infections and conjunctivitis, were detected in 36.4 percent of the samples. Noroviruses, responsible for causing gastroenteritis, turned up in 9.4 percent of the time.