Summary: Essential pool contamination procedures protect health, ensure compliance, and minimize downtime from fecal, vomit, or blood incidents.

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The reality of working in pools is that sometimes, things just happen that are out of your control. This includes contaminations in your pool water, whether it’s a fecal incident, vomit, or blood contamination. However, being prepared to respond and carry out the proper pool contamination procedure is essential to protect public health, number one, avoid non-compliance, and minimize the extent of the damage and downtime. 

In this post, we'll outline what pool contamination means, common types of contamination, and step-by-step procedures every pool owner or manager should follow in the event of a contamination incident.

Understanding Pool Contamination

Pool contamination refers to the presence of harmful substances or organisms in the water that could pose a health risk to swimmers.

This includes, but is not limited to:

• Fecal matter (any kind)
  
  
• Vomit
  
  
• Blood
  
  
• Chemical spills or imbalances

Each type of contamination carries its own level of risk and requires a specific response. The CDC’s Model Aquatic Health Code (MAHC) and your local health department guidelines should be your primary references for procedures, but for your convenience, we’ve put together a summary of widely accepted protocols (based on the MAHC).

Why Prompt Action is Essential for Addressing Pool Contamination

While contaminants like leaves and debris can create an easy breeding ground for algae, human contaminants can carry disease. Their presence in the water can spread Recreational Water Illnesses (RWIs), including Cryptosporidium, Giardia, E. coli, and norovirus. Even with properly chlorinated water, some pathogens like Cryptosporidium are highly chlorine-resistant and can survive for multiple days without appropriate treatment.

A delayed or inadequate response to pool contamination can result in:

• Illness outbreaks
  
  
• Temporary facility closures
  
  
• Legal liabilities
  
  
• Reputational damage

Step-by-Step Pool Contamination Procedures

1 - Immediate Pool Closure

As soon as a pool contamination event is identified, it’s important to :

• Clear all swimmers from the pool immediately. Explain clearly why pool closure is necessary, as this will help minimize guest frustration.
  
  
• Close off access to the affected pool (including splash pads, spas, etc.).
  
  
• Document the time and nature of the incident, as well as the chlorine concentration and pH at time of incident. This is an important compliance step and it will also help you throughout your contamination response process, as you document the steps taken and changes in water chemistry.
  
  

2 - Respond Based on the Type of Contamination

Your next steps will depend on the type of contamination:

Formed Stool

Because germs are typically contained inside formed poop, this typically poses a lower risk than diarrhea. However, this also means the germs are protected from chlorine’s disinfecting ability–and the longer it sits in pool water, the worse the impression on your pool guests.

Formed Stool Pool Contamination Procedure:

• Put on disposable gloves and remove the fecal material using a net or scoop. Do not vacuum.
  
  
• Disinfect any equipment used during cleanup.
  
  
• Raise chlorine levels, or maintain at, 2 ppm and pH to 7.5. Water temperature should ideally be at 77℉ during disinfection.
  
  
• Maintain the pool at these levels for 30 minutes.
  
  
• Check to ensure the filtration system is working properly, then backwash the filter once chlorine and pH levels have been maintained for 30 minutes. Discharge directly to waste and follow local and state requirements. Do not return the backwash through the filter, and replace the filter if necessary.
  
  
• Reopen the pool after the 30-minute contact time and once chlorine levels return to normal (1–3 ppm for most pools).

Diarrheal Incident

This is a high-risk event due to the likelihood of pathogens like Cryptosporidium, which is chlorine-resistant. If you have pool stabilizer (cyarunic acid) in the water, you should follow steps to hyperchlorinate the water. 

Diarrheal Incident Pool Contamination Procedure:

• Put on gloves and remove as much of the material as possible with a scoop or net. Do not vacuum.
  
  
• Maintain pH between 7.2 and 7.5.
  
  
• If pool stabilizer levels concentration is between 1-15 ppm, you have a few options. Use unstabilized chlorine (liquid chlorine) to:
  • Raise free chlorine to 20 ppm and maintain for 28 hours,
  • Raise free chlorine to 30 ppm and maintain for 18 hours, or
  • Raise free chlorine to 40 ppm and maintain for 8.5 hours.
    
    
• If pool stabilizer levels are above 15 ppm, drain water partially and add fresh water (without stabilizer) to lower the CYA levels to below 15 ppm. Then, follow the steps to hyperchlorinate.
  
  
• Check to ensure the filtration system is working properly, then backwash the filter once chlorine and pH levels have been maintained for 30 minutes. Discharge directly to waste and follow local and state requirements. Do not return the backwash through the filter, and replace the filter if necessary.

Return chlorine to normal levels before reopening.

Vomit

Vomit happens when pool guests are sick, but it can also happen when they accidentally swallow too much water. While this scenario is less likely to contain germs, any vomit that contains stomach contents such as previously eaten food may contain norovirus or other pathogens.

Vomit Pool Contamination Procedure:

• Treat similar to formed stool unless blood is visible or vomiting was preceded by illness symptoms (in which case follow diarrheal procedure).
  
  
• Remove debris.
  
  
• Maintain chlorine at 2 ppm for 30 minutes.
  
  
• Reopen once levels are restored.

Blood

Bloodborne pathogens are not easily transmitted via properly chlorinated pools, as the chlorine effectively kills germs found in blood, such as hepatitis B. However, it can still be a good response to follow a clean up procedure similar to vomit or poop.

Blood Pool Contamination Procedure:

• If water chemistry is within ideal range (chlorine ≥1 ppm, pH 7.2–7.8), no closure is necessary.
  
  
• Remove visible blood with scoop or vacuum if needed.
  
  

Continue Normal )perations

• 5 tablespoons (1/3 cup) of bleach per gallon of room temperature water or
• 4 teaspoons of bleach per quart of room temperature water

Add the household bleach to the water and gently mix them together.

Gently pour the bleach solution on the contaminated surfaces and leave there for 20 minutes. Wipe up bleach solution with paper towels; throw away paper towels and gloves. Disinfect any cleaning materials that cannot be thrown away and leave to air dry. Double bag any trash. 

*Note: After all pool contamination procedures, staff should thoroughly wash hands with soap and water.

Communication and Documentation Regarding Pool Contamination Procedures Above

A critical but often overlooked component of contamination response is recordkeeping and communication:

• Log every incident in your operation manual or incident report log, noting:
  
  
  • Time and date
    
    
  • Type of contamination
    
    
  • Chlorine and pH levels at the time
    
    
  • Remedial actions taken
    
    
  • When the pool reopened
    
    
• Inform your local health department if required by law.
  
  
• Consider posting signage or informing patrons if an extended closure is needed.
  
  

Pool Contamination Prevention Strategies

While no pool is immune to contamination, you can reduce the frequency and impact by implementing the following:

• Pre-swim showers: Encourage or require patrons to rinse before entering. Post signs with this recommendation/requirement, and make showers easily accessible near the pool entrance.
  
  
• Swim diapers: Swim diapers should be mandatory for infants and toddlers.
  
  
• Signage and education: Remind patrons not to swim while sick, especially with diarrhea.
• Implement regular adult swim periods: Make an announcement at each one encouraging parents to check and change diapers and take children to the restroom.
  
  
• Regular staff training: All staff should know how to identify and respond to incidents.
  
  
• Water testing: Frequent testing (ideally hourly) helps catch chemical imbalances early.
  
  

Final Thoughts on Pool Contamination Procedures

Pool contamination procedures are critical protocols that protect public health and keep your facility in compliance. As a commercial or public pool operator, having a well-documented plan, trained staff, and the right equipment on hand can make all the difference in turning a potential crisis into a controlled situation.

Maintaining balanced pool water, including cyanuric acid levels, can also make a difference in your ability to respond quickly and remediate water. The Pool Shark H2O app makes it quick and simple to test water and adjust chemicals. It automatically performs complex pool chemical math equations for you, eliminating guesswork and forgery risk. Pool managers can receive automated alerts when pools need attention or tests are missed, reducing your number of physical visits to your pools while ensuring pool water is safe, maintained, and 100% Health Department compliant. Pool logs are automatically locked and archived, and Pool Shark H2O also provides the essential Pool Contamination Incident Report Logs you need to stay compliant and ensure your pools are safe to reopen.