Recreational Water Illness (RWI) Fecal Incident Response Log

Documents pool closure, hyperchlorination, contact time, and reopen approval following a formed or diarrheal fecal incident. Supports compliance with CDC Model Aquatic Health Code (MAHC) fecal incident response guidelines.

Incident Identification and Initial Response

• Date and time fecal incident was discovered
  Record the exact date and time the incident was first observed by staff.
• Name and role of staff member who discovered the incident
  Enter the full name and job title (e.g., Lifeguard, Pool Operator) of the staff member who identified the incident.
• Pool or aquatic area where incident occurred
  Specify the pool name or zone (e.g., Main Pool, Kiddie Pool, Lap Lane Area, Splash Pad).
• Incident classification
  Classify the incident type per CDC MAHC guidance. Formed stool and diarrheal incidents require different hyperchlorination targets. Vomit incidents follow a separate protocol.
• Pool was immediately closed to all bathers upon discovery
  All swimmers must be cleared from the affected pool immediately. Do not allow re-entry until the full disinfection protocol is complete and reopen criteria are met.
• Fecal matter removed from pool using a net or scoop (do not vacuum)
  Remove as much fecal material as possible using a net or scoop. Dispose of material in a sanitary waste container. Do NOT use a pool vacuum, as this can spread contamination. Disinfect the net/scoop after use.

Pre-Hyperchlorination Water Chemistry Baseline

• Baseline free chlorine (FC) level — pre-treatment
  Measure and record the current free chlorine concentration in ppm before adding any hyperchlorination chemicals.
• Baseline pH level — pre-treatment
  Record the current pH. CDC guidance requires pH to be adjusted to 7.5 or lower before hyperchlorination to maximize disinfection efficacy. At pH 7.5, chlorine is approximately 50% in the active hypochlorous acid (HOCl) form.
• pH adjusted to 7.5 or below prior to hyperchlorination
  If baseline pH exceeds 7.5, add pH-decreasing chemical (e.g., muriatic acid or sodium bisulfate) and retest before proceeding. Document adjustment in comments.
• Cyanuric acid (CYA) / stabilizer level — pre-treatment
  Record CYA level. Note: CDC MAHC recommends that pools with CYA present use higher chlorine targets or drain/dilute, as CYA significantly reduces chlorine disinfection efficacy against Cryptosporidium. If CYA > 15 ppm, consult your state/local health authority.
• Water temperature at time of incident
  Record pool water temperature. Temperature affects CT (concentration × time) calculations. Cooler water may require extended contact times.

Hyperchlorination Protocol

• Hyperchlorination target free chlorine level based on incident type
  Select the CDC-recommended target free chlorine level for this incident type. Formed stool: 2 ppm. Diarrheal: 20 ppm. These targets assume pH ≤ 7.5 and no cyanuric acid.
• Type and amount of hyperchlorination chemical added
  Record the chemical name (e.g., liquid sodium hypochlorite 12.5%, calcium hypochlorite granules, trichlor), concentration, and quantity added (gallons or pounds). Include lot number if available.
• Date and time hyperchlorination chemical was added
  Record the exact time hyperchlorination began. This is the START time for CT (concentration × time) calculation.
• Confirmed free chlorine level reached after chemical addition
  Test and record the free chlorine level after chemical addition and circulation. Must meet or exceed the target level (2 ppm for formed stool; 20 ppm for diarrheal) before starting the contact time clock.
• Confirmed pH level after chemical addition
  Retest pH after adding hyperchlorination chemicals. Must remain at or below 7.5 throughout the contact time period.
• Circulation/filtration system confirmed running during entire contact time
  The pool recirculation and filtration system must run continuously during the full contact time period to ensure uniform distribution of the disinfectant throughout the pool volume.
• Pool filter backwashed after contact time is complete (diarrheal incidents)
  For diarrheal incidents, CDC recommends backwashing the pool filter after the contact time is complete to remove Cryptosporidium oocysts captured in the filter media. For formed stool incidents, backwashing is recommended but may not be required by all jurisdictions — confirm with local AHJ.
• Additional notes on hyperchlorination process
  Document any deviations, challenges, or additional steps taken during hyperchlorination (e.g., multiple chemical additions, equipment issues, partial pool treatment).

Contact Time Verification (CT Value)

• Required minimum contact time for this incident type
  Select the minimum contact time required based on incident classification and CDC MAHC targets.
• Contact time start — date and time
  Record the date and time when the target free chlorine level was confirmed and the contact time clock officially started.
• Contact time end — date and time
  Record the date and time when the required contact time was completed.
• Total elapsed contact time (minutes)
  Calculate and record the total elapsed time in minutes from contact time start to end. Must meet or exceed the required minimum (25 min for formed stool; 765 min for diarrheal).
• Free chlorine level confirmed at or above target throughout contact time
  Confirm that free chlorine was tested at regular intervals during the contact time and remained at or above the target level (2 ppm or 20 ppm). If chlorine dropped below target at any point, the contact time clock must be restarted.
• pH confirmed at or below 7.5 throughout contact time
  Confirm that pH remained at or below 7.5 for the entire contact time period. pH above 7.5 reduces disinfection efficacy and may invalidate the CT calculation.

Post-Treatment Water Chemistry and Reopen Criteria

• Post-treatment free chlorine level
  Measure free chlorine after contact time is complete. Pool must not reopen until free chlorine is reduced to the safe operating range (typically 1–10 ppm for most jurisdictions; confirm with local AHJ). Excess chlorine may require dilution or dechlorination.
• Post-treatment pH level
  Confirm pH is within the safe operating range (7.2–7.8 per CDC MAHC) before reopening.
• Post-treatment combined chlorine (chloramines) level
  Record combined chlorine level. Should be below 0.4 ppm per CDC MAHC. Elevated combined chlorine may indicate incomplete disinfection or need for breakpoint chlorination.
• Post-treatment total alkalinity
  Record total alkalinity. Acceptable range is typically 60–180 ppm. Alkalinity outside this range can destabilize pH control.
• All post-treatment water chemistry parameters are within acceptable limits for reopening
  Confirm that free chlorine, pH, and all other required parameters are within safe operating ranges per CDC MAHC and local health authority requirements before authorizing reopen.

Reopen Authorization and Record Retention

• Local health authority notified of diarrheal incident (if required by jurisdiction)
  Many state and local health codes require notification of the health authority for diarrheal fecal incidents. Check your jurisdiction's requirements. If not applicable (formed stool only), select N/A and document in comments.
• Health authority notification date, time, and contact name (if applicable)
  If the health authority was notified, record the date, time, method of notification (phone, email, online portal), and the name of the health authority contact.
• Pool reopened — date and time
  Record the official date and time the pool was reopened to bathers after all reopen criteria were confirmed met.
• Name and role of staff member authorizing pool reopen
  Enter the full name and role (e.g., Certified Pool Operator, Aquatic Director, Health Inspector) of the person who authorized the pool to reopen.
• Photo documentation of post-treatment water chemistry test results
  Attach a photo of the test kit or digital reader showing post-treatment free chlorine and pH readings. This provides visual evidence for health department audits.
• This log will be retained on file for a minimum of 2 years (or per local AHJ requirement)
  Confirm that this completed log will be stored in the facility's records system for the required retention period. Confirm the retention period with your state/local health authority.
• Inspector / Pool Operator Signature
  Signature of the Certified Pool Operator (CPO) or responsible aquatic staff member completing this log.