Every year, the CDC documents thousands of recreational water illness (RWI) outbreaks. The 2013 inspection blitz found 1 in 8 public pools had to close immediately for health violations. Nearly every RWI outbreak is preventable — if the operator knows what to look for and has the playbook ready.
This pillar is the CDC- and MAHC-aligned RWI reference. How pathogens enter pools, which ones chlorine handles easily and which ones don't, and the exact response protocols when contamination happens.
The RWI threat model
Two categories of RWIs matter to operators:
- Fecal-related: Cryptosporidium, Giardia, E. coli, Shigella, Norovirus, Hepatitis A. Spread by swallowing contaminated water.
- Non-fecal: Pseudomonas (hot tub rash, swimmer's ear), Legionella (Legionnaires', Pontiac fever), MRSA, HP, molluscum, athlete's foot. Spread by aerosols or surface contact.
Why chlorine alone isn't always enough
Chlorine kills E. coli in under a minute at 1 ppm. It needs 16 minutes for Hep A, 45 minutes for Giardia, and over 15,000 minutes (10 days) for Cryptosporidium. Different pathogens require different responses, and Crypto needs a totally different protocol than every other RWI.