PWTAG has published a lot over the years – books, technical notes and guidance, a code of practice, posters, articles, even a history of its 50 years – but never in the formal scientific press. Until now. Published this week in Water, an open-access, peer-reviewed journal from the Multidisciplinary Digital Publishing Institute (MDPI) is an important article that draws on and extends PWTAG’s work [1]. Three of its twelve authors are PWTAG council and industry forum members and their 24-page article examines in considerable detail the importance of circulation rate guidelines.
Looking from the UK, the article finds that the determination of bathing load is relatively consistent across many European countries. They all look first to the physical space required for safe pool activities. But circulation rate calculations are much more variable. They fall into two camps:
- rule-based, based primarily on turnover times, with recommended values for different types of pool – eg Spain, France, Italy, Greece
- based primarily on bathing load, focused on removing each bather’s contaminants – eg UK, Germany, Norway, Denmark.
Circulating pool water accounts for about a third of all a pool building’s energy use – about the same as heating the water. So this study was interested in exploring the possibility that the second method offered more opportunity for savings through risk-management. – even if that is more of a challenge for relatively unskilled pool operators. Cryptosporidium oocysts, as well as turbidity, were used as a measure.
The paper notes that the German DIN standard and the more rule-of-thumb approach of PWTAG guidelines both arrive at similar, satisfactory figures for bathing load. There is much more detail here about all this.
[1]Managing bathing loads and circulation rates in commercial swimming pools: rationale and perspective from UK and Europe. Water 2025, 17, x.
Interestingly, the Netherlands has recently moved completely from rules to risk-based management on the plan-do-check act concept. New legislation encourages pool operators to combine healthy swimming with sustainable operation. The Water paper favours this concept, which allows a more flexible approach to reducing circulation rate when the pool is closed, as well as the use of variable speed pumps.
This detailed review is important confirmation of the approach to safe pool water management employed by PWTAG and other influential European authorities. But it also indicates areas that further research could usefully follow. Further, despite its length and detail, there is much in it for anyone professionally concerned with running pools. Dive in.
Website: https://www.mdpi.com/2073-4441/18/6/713
PDF Version: https://www.mdpi.com/2073-4441/18/6/713/pdf