Managing Bathing Loads and Circulation Rates in Commercial Swimming Pools: Rationale and Perspective from UK and Europe

Circulation of pool water via a treatment plant is critical for maintaining pool water in a condition that is a safe and attractive for bathers. It is also one of the pool operations that is most costly in terms of energy used and associated carbon footprint. In this study, we compare and contrast circulation rate guidelines developed for the UK and for other northern and southern European countries and, where possible, provide an explanation of the underlying rationale. We focus on the management of turbidity-forming material and Cryptosporidium oocysts. We reveal that the parameters used to assess safe operational bathing load are relatively consistent across Europe, based on physical space requirements for bathing and other constraints such as lifeguarding. Circulation rate, on the other hand, is based on either rule-based turnover times, or a more flexible approach based on the volume of water to be treated per bather. The latter offers scope for innovation and energy savings, with the proviso that safe water is maintained for bathers. The guidance in several countries suggests reducing circulation rate when the pool is not being used by bathers. We conclude that a more progressive risk-based approach to pool management, building on these findings, offers significant opportunities for pool operators to run pools better and should be a priority for future research.