According to the CDC, there has been a substantial increase in the number of outbreaks associated with swimming. Cryptosporidium, the usual culprit, is chlorine-tolerant, surviving for up to 10 days in properly chlorinated pools. Additional microorganisms such as E. coli, Giardia, Shigella and norovirus contribute to recreational water infections, albeit less due to chlorine susceptibility.

To prevent infection, water goers are encouraged to shower prior to swimming, avoid swallowing pool water and avoid swimming altogether if experiencing symptoms of infection, especially children. Chlorine levels should be maintained at 1.0 – 3.0 ppm and checked regularly.


In addition to chlorine, bromine, ozone, and ultraviolet light are all effective pool sanitizers.  Chlorine is most popular because it is inexpensive and low residual levels provide protection against microbial growth, including algae.


If your company is interested in registering an antimicrobial agent for use in pools, EPA will require testing per AOAC 956.13, which compares efficacy of the candidate antimicrobial to carefully prepared chlorine standards.  In addition, the Agency may require long-term field studies.  Texas has a long pool season, so Antimicrobial Test Laboratories is well suited to help.