Poop in the Pool

The germs that cause recreational water illnesses (RWIs) can be spread when swallowing water that has been contaminated with fecal matter (poop). How? If someone has diarrhea, that person can easily contaminate an entire aquatic venue. The water is shared by all swimmers. It’s communal bathing water. It’s not sterile. It’s not drinking water.

The good news is that most germs causing RWIs are killed by chlorine within a few minutes. However, chlorine doesn’t kill everything right away. It takes time to kill germs and some germs, such as Cryptosporidium (or Crypto for short), can live in properly treated water for days. This means even the best maintained aquatic venues can spread germs.

Time to Kill or Inactivate Germs in Chlorinated Water *

Time to Kill or Inactivate Germs in Chlorinated Water
Germ Time
E. coli O157:H7 Bacterium Less than 1 minute
Hepatitis A Virus About 16 minutes
Giardia Parasite About 45 minutes
Crypto Parasite About 15,300 minutes or 10.6 days 1

Aquatic staff should document each fecal incident in an aquatic venue by recording date and time of the event, whether it involved formed fecal matter or diarrhea, and the free chlorine concentration and pH at the time or observation of the event. Download a template log by clicking on the links below:


  1. Shields JM, Hill VR, Arrowood MJ, Beach MJ. Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions. J Water Health 2008;6(4):513–20.

* 1 part per million (ppm) free chlorine at pH 7.5 or less and a temperature of 77°F (25°C) or higher.

Page last reviewed: April 2, 2022