Handling a Fecal Accident in a Chlorinated Swimming Venue

 

NOTE: These guidelines do not apply to the use of nonchlorinated disinfectants, since there is only limited data on pathogen inactivation using these agents.

 

Types of fecal accidents:

(1) formed (nonliquid) stool

(2) diarrhea (liquid stool)

 

General Response to All Fecal Accidents

 

(1) Direct everyone to leave the pool. No one should be permitted to use the pool until the disinfection process is complete.

(2) Remove as much fecal material as possible using a net or scoop. Dispose of this in a sanitary manner. Vacuuming is not recommended.

(3) Raise the free available chlorine concentration to the recommended level based on the type of soiling. The pH should be maintained in the range 7.2 to 7.5. Samples for testing should be taken at 3 widely spaced locations away from the return water outlets.

(4) Ensure that the filtration system is operating while the pool reaches and maintains the proper free available chlorine concentration during the disinfection process.

(5) Establish a fecal accident log and document the event, giving the date, time, type of accident, free chlorine concentration and disinfection treatment time.

 

Formed Stool

 

(1) The usual target for free available chlorine is 2 mg/L. This will limit the pool closure time to 25 minutes. If the free chlorine level differs, then the period for disinfection will vary according to the table below.

(2) Once the time period has elapsed, the pool may be reopened for use.

Concentration of Free Available Chlorine in mg/L or parts per million (ppm)	Pool Closure Time in minutes
<= 0.4	105
0.6	72
0.8	55
1.0	45
1.2	39
1.4	34
1.6	30
1.8	28
2.0	25
2.2	24
2.4	22
2.6	21
2.8	20
3.0	19

 

Liquid Stool

 

(1) The goal of disinfection after a liquid stool accident is to be able to destroy Cryptosporidium.

(2) The CT (concentration of free chlorine • time in minutes) value to inactivate Cryptosporidium is 9,600. The usual target free chlorine concentration is 20 mg/L which will disinfect the pool in 8 hours.

 

duration to close pool in minutes =

= 9600 / (concentration of free chlorine in mg/L or parts per million)

 

(3) Backwash the filter thoroughly after reaching the CT value. The effluent should be discharged directly to waste. Do not return the backwash through the filter. Consider replacing the filter media.

(4) Once the disinfection period has been completed, the level of chlorine should be reduced to normal before swimmers can be allowed to use the facility.