However, "you can't always tell by looking at pool water if it is properly disinfected", according to Hvalsa.
Crypto can also be spread by swallowing contaminated water from water parks, interactive fountains, water play areas, hot tubs, lakes, rivers, springs, ponds, streams, and oceans. One of the suggestions include not allowing children to use the pool if they have diarrhoea.
The parasite has a high tolerance for chlorine and can live in a pool for up to a week.
Cryptosporidiosis, a diarrheal disease caused by Cryptosporidium parvum protozoan.
The greatest single source for the outbreaks was contaminated chlorinated water, such as pools and water playgrounds, the CDC said.
Outbreaks of cryptosporidiosis rose an average of 13% every year from 2009 to 2017, according to a report published by the CDC last week.
It's also worth noting the one death from cryptosporidiosis came in the sole instance in which the parasite was transmitted in a hospital setting.
Between 2009 and 2017 there was a 12.8 percent increase in crypto cases, most of which were reported in July and August, according to the CDC.
Norovirus, which causes vomiting and diarrhea that lasts for up to 72 hours, is another virus that can be found in pool water, though occurrence is more rare than other RWIs, and it is the leading cause of acute gastroenteritis (intestinal infection) among American children under the age of 5.
The number of summertime parasite outbreaks continues to grow, public health officials say, and most people catch the bug in pools and water playgrounds.
Outbreaks of crypto are most common in the summer, the report says, and anyone with diarrhea should not swim or enter public pools or playgrounds. It typically causes up to three weeks of watery diarrhea. Michele Hvalsa, chief of CDC's Healthy Swimming Program, recommends making sure the drain at the bottom of the deep end is visible before getting in.
Crypto can easily cause outbreaks because it only takes a few germs to make someone sick and there can be millions of Crypto germs in poop, the CDC reports.
Test strips could be purchased from hardware stores to look for adequate chlorine or bromine levels as well as correct pH of the water.