Loss of visibility in the swimming pool environment

 GUIDANCE

What is visibility? 

Visibility is, in the swimming pool context, a state of having a line of sight from the allocated lifeguard position or patrol route to the location of a pool user within their zone of supervision. 

Why does losing visibility matter? 

The prevailing method of supervision for unprogrammed sessions is zone surveillance by means of scanning all areas of the zone of supervision for danger. This is due to the variable headcount that exists between points throughout the session, which substantially decreases the reliability of head counting as a method to identify a person in danger. Losing visibility in an unprogrammed session effectively leaves a zone of the pool unguarded. 

How might visibility be lost? 

Visibility may be lost due to: 

• Specular or diffuse reflection. 
• Poor water turbidity. 
• Buoyant obstructions such as floats. 
• Fixed obstructions such as pillars or a large inflatable. 
• Mobile obstructions such as pool users. 
• Loss or reduction in artificial or natural illuminance. 
• Change in the lifeguard position or patrol route. 
• Change in the eyesight of the lifeguard. 
• The distraction of the lifeguard from the zone of supervision. 
• Failure of CCTV display screen equipment. 
• Fogging or obstruction of poolside mirrors. 

How do the team determine when turbidity (water clarity) is insufficient? 

The team should determine that turbidity is insufficient in the same way they determine a loss of visibility by any other means. If the line of sight from the allocated lifeguard position or patrol route to the location of a pool user within their zone of supervision is lost, then visibility has been lost, and the pool must take immediate action to safeguard the safety of pool users. 

Turbidity, illuminance, and other quantifiable environmental conditions should not be relied on to determine whether visibility has been lost. They should be used to inform and prompt the assessment of conditions by a human being. 

How should the team respond where visibility is lost?

The standard of supervision will be in breach where scanning is the chosen method of ensuring pool users' safety in an unprogrammed session. Failure to maintain the standard of supervision results in an operator exposing pool users to a risk to their health and safety. Pool activities should cease with immediate effect until the operator's provision can once again meet the standard of supervision.

Where visibility has been lost, the following actions should be considered: 

• Temporary increase in lifeguard cover. 
• Temporary closure of all or part of the pool. 
• Modification to the lifeguard position or patrol route. 
• Deployment of additional warning signs and barriers. 
• Backwashing the pool water and/or increasing freshwater intake. 
• Replacement of filter medium.
• Deployment or defogging of mirrors. 
• Increase in artificial illuminance. 
• Removal of lifeguard distraction. 
• Removal or reduction in buoyant obstructions. 
• Repair of existing CCTV screens. 
• Deployment of additional CCTV display screen equipment. 

Citation: Jacklin, D. 2021. Loss of visibility in the swimming pool environment. Water Incident Research Hub, 28 December.