THE PWTAG CONFERENCE concluded that well treated pools can run safely de
THE PWTAG CONFERENCE concluded that well treated pools can run safely despite Covid-19.

PWTAG’s first online conference ran as smoothly as the deadly virus, Covid-19, which was its theme. It was an ambitious programme: reports and research from across Europe and the US. And an ambitious format: presented live (much of it recorded in advance but taking questions live) with paper sessions and live interactive workshops run in parallel – and a live ask-the-experts session at the end. Between and at the end of sessions, there was a never-ending queue of eager questioners. £40 can still buy you access to all 14 papers and other reports (

The overall message was clear and one hopes unsurprising. Yes, pools can run safely despite Covid, provided disinfection is scrupulously attended to and particular care taken with ventilation, hygiene and distancing. In the US, CDC’s Model Aquatic Health Code is a suprisingly democratic affair. Subscribers get to vote on contentious issues. This year’s MAHC update is the subject of controversy on such issues as cyanurates and swimming ponds. Talking of cyanurates, the MAHC’s specialist on it, Richard Falk, emphasised the importance of controlling its ratio with free chlorine. It got complicated, but the bottom line (Covid in faeces) was a risk of about 1 in 180 million. Professor Spica’s paper on the Italian experience (no pool-related outbreaks) had 70 Covid references from 2020/21 – none from the UK.

The news from Austria was a revelation. Legislation dictates filtration, dye testing, chlorine residuals, pH, redox – and a 4-log reduction of Pseudomonas aeruginosa within 30 seconds. They favour process control to end-product control. Dutch researchers have a very direct appoach. Jan Bakker observed, Covid-tested and health checked swimmers. The only problem was the misbehaviour of young swimmers. This despite disinfection issues, including high chlorate. Maarten Keuten’s team measured aerosols directly. Recreational equipment could quadruple aerosol levels; upping outside air and fan speed could half it again. Christiane Holler reported on the political pressures to reopen pools in Bavaria: when they did, in June last year, distancing was difficult to enforce and there were two Covid cases linked to a spa. Greece was challenging too. Athena Mavridou and colleagues surveyed pool managers: half found hygiene measures difficult to apply and had often failed to install screens.

Poly Water Treatment Advisory Group