Chlorine Disinfection Timetable
![Close-up of the element chlorine on the periodic table of elements.](https://webarchive.library.unt.edu/web/20121007145727im_/http://www.cdc.gov/healthywater/images/swimming/chlorine-periodic-table.jpg)
Timetable for killing common illness-causing germs
Free chlorine kills most bacteria such as E. coli 0157:H7 in less than a minute if it is maintained at proper disinfection levels (1-3 parts per million [ppm] free chlorine) and under ideal water conditions (pH at 7.5 or less; temperature at 77° F [25° C] or more) throughout the pool. However, a few germs are moderately (Giardia, Hepatitis A) to highly (Cryptosporidium) chlorine-tolerant. The table below shows the approximate disinfection times for these germs in chlorinated water.
Agent | Disinfectant Times for Fecal Contaminants in Chlorinated Water |
---|---|
E. coli 0157:H7 (Bacterium) |
less than 1 minute |
Hepatitis A (Virus) |
approximately 16 minutes |
Giardia (Parasite) |
approximately 45 minutes |
Cryptosporidium (Parasite) |
approximately 15,300 minutes (10.6 days) |
Notes:
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