July 1, 2019 — That crystal clear swimming pool looks so inviting as the thermometer climbs this summer. But the CDC is warning that danger lurks in many of America’s pools. Outbreaks of diarrhea-causing cryptosporidium are increasing 13% each year, and 7,465 cases of crypto infection were reported from 2009 through 2017. The number of outbreaks reached 444, according to the agency’s report released last week. But it’s not just crypto that swimmers have to be wary of. The CDC says 493 outbreaks of some kind of bacteria, parasite, or chemical between 2000 and 2014 were associated with recreational facilities, including pools, hot tubs, and playgrounds, and caused 27,219 cases and eight deaths. Most of those deaths were caused by bacteria or other pathogens, and 6% by chemicals. Just last month, about 50 people were exposed to chlorine gas after a pump malfunctioned at a public swimming pool in Utah. The pump shot too much chlorine out of a jet in what local police called a “freak accident.” Of the outbreaks caused by bacteria and viruses, 58% were caused by cryptosporidium, which causes diarrhea that can last for up to 3 weeks. Thirteen percent were from pseudomon...