Every commercial pool will eventually have a fecal incident. The right response protects swimmers, defends the facility legally, and gets the pool back open as fast as safely possible. These are the CDC-aligned protocols.
The three categories (and why they're different)
| Type | Primary risk | Response |
|---|---|---|
| Formed stool | Giardia-class pathogens | 1 ppm FC for 25+ min (CT ≈ 25) |
| Diarrheal stool | Cryptosporidium | 20 ppm FC for 12.75 hrs (CT ≈ 15,300) |
| Vomit / blood | Bloodborne pathogens | Same as diarrheal — treat as worst case |
Formed stool protocol
- Instruct swimmers to leave the pool. Do not let anyone back in.
- Remove the stool with a net or bucket. Discard in a trash bag.
- Disinfect the scoop/net with bleach before reusing.
- Raise free chlorine to 2 ppm if below. Hold pH 7.2–7.5.
- Run circulation for 25 minutes minimum (enough for CT ≥ 50 ppm·min).
- Vacuum to waste any sediment.
- Document: time, operator, chlorine readings, action. Reopen.
Diarrheal stool protocol (the Crypto protocol)
This is the same as the Crypto hyperchlorination response — because you assume it contains Crypto until proven otherwise.
- Close the pool immediately. Post signage.
- Remove as much of the stool as possible.
- Reduce CYA to < 15 ppm if currently higher. Partial drain/refill.
- Adjust pH to 7.5 or below.
- Raise free chlorine to 20 ppm with unstabilized chlorine.
- Hold for 12.75 hours, testing and redosing every 2–4 hours.
- Replace or chemical-soak filter media during the hold.
- Lower FC to normal. Verify. Reopen.
Vomit or blood protocol
Vomit and blood can contain Norovirus, Hep A, Hep B, HIV, and other pathogens. Treat them with the same rigor as a diarrheal incident — the 20 ppm / 12.75 hr Crypto protocol. This is conservative, but the cost of under-responding to a bloodborne-pathogen exposure is unacceptable.
Documentation requirements
Every fecal incident must be logged with:
- Date and time of incident
- Incident type (formed / diarrheal / vomit / blood)
- Operator name
- Chlorine and pH readings at start, during hold, and at reopen
- Circulation verification (flow confirmed)
- Action taken, time of reopen, signage posted
Some jurisdictions require reporting diarrheal incidents to the county health department within a specified time window (often 24 hours). Know your local rule.
Preventing next time
- Enforce “no swim with diarrhea” signage and staff vigilance
- Swim-diapers required for children under 3 in kiddie pools
- Scheduled bathroom breaks for children's programs
- Pre-swim showers at all entrances
- Consider UV or ozone secondary disinfection for high-risk venues