Memorial Day weekend is when many pools and beaches open for the unofficial start to summer. It is important people know how they can protect themselves and prevent the spread of germs when swimmingDiarrhea is the most common cause of recreational water illness (RWI). Just one diarrheal accident in the water can release millions of germs. If other swimmers swallow a mouthful of the water, it can cause diarrhea lasting up to three weeks. Crypto (short for Cryptosporidium) is the leading cause of outbreaks linked to pools and water parks. Crypto can survive in an adequately chlorinated pool for more than one week. Other germs that can cause illness include Giardia, norovirus, Shigella, and E. coli. RWIs can also be caused by chemicals added to treat water. Other common RWIs include skin, ear, respiratory, eye, neurologic, and wound infections.