Pool operators need to establish two different types of bather load for swimming pools:
Instantaneous bather load
This is maximum number of bathers in any given instance (e.g., public swim).
The typical starting point for determining this is to allow at least 3 square metres of water surface area per pool user. But this is only a guide. The risk assessment should take other factors into account, e.g.:
- Swimming ability
- Age of swimmers
- Visibility
- Lifeguard provision
Example:
Length x Width = 300 sq. metres
300 sq. metres / 3 = max. bather load of 100
Total daily bather load
This is maximum number of bathers the pool and treatment system is designed to cope with per day.
Pool operators need to establish sensible limits on the maximum number of bathers that can use the pool on a daily basis.
To work this out, you take the instantaneous bathing load (see above), take 25% to 50% of it and multiply by 12 (or, the number of daily opening hours).
Pool operators should only go to the upper end of the range if they are confident that the pool plant system can handle it and maintain good water quality. If in doubt, the advice would be to stay in the bottom half of the range.
Example:
25% to 50% of max. bather load of 100 = 25 to 50 bathers
25 to 50 bathers x 12 = 300 to 600 bather per day