The first-ever reported case of Pseudomonas aeruginosa in float water has shed light on whether floatation tanks pose a potentially higher health risk than hot tubs or other recreational water facilities.
The case, investigated by Vancouver Coastal Health, hints that a certain mix of filtration failure, weakened disinfection, or salinity shifts could quietly set the stage for pseudomonas to take hold.
Pseudomonas, also nicknamed “hot tub rash,” likes warmer water. This type of bacteria causes skin irritations alongside other symptoms, like fever, headache, sore throat, swollen lymph nodes, fatigue, and ear infections. It is often used as a test bacterium here at NSF when we test for the efficacy of disinfection equipment, like a UV or ozone system.
An illness like pseudomonas is triggered by skin contact; unlike other GI disorder-causing bacteria, it does not have to be ingested. And contamination by skin-irritating bacteria in float facilities is more likely simply because it is hard to swallow the amount of saltwater required to fall ill from, say, E. coli or giardia.
The case describes a customer who was placed in a float tank that had been non-operational for a couple of weeks. This individual developed a serious case of pseudomonas beyond a simple rash and had to go to the hospital and go through multiple rounds of antibiotics to kick it.
The researchers noted that there was a lack of vigilance and several infractions in the management of the float facility.
First, the filtration system on this tank did not run for two weeks, nor was the tank properly disinfected. While British Columbia requires chlorine, the facility operators didn’t put any chlorine in during that time. This means the customer sat in stagnant float tank water for 60 minutes.
The investigators were able to establish that the person’s illness was linked to the float tank by looking at the window of time before symptoms developed and ruling out any other venue that could have gotten them sick, like a pool, hot tub, water park or hotel room bathtub.
The results of the float tank water testing revealed very high levels of pseudomonas, though they could not exactly match the strain from the float tank to that found in the person. But the sampling was done after antibiotics, and pseudomonas strains do mutate.
The person who got sick also reported an inability to float freely in the tank, which might be related to low magnesium levels. The water activity of a float tank with adequate magnesium sulfate (Epsom salt) will kill pseudomonas naturally on its own.
The health authorities of British Columbia have one of the most robust sets of float tank regulations in North America. Yet the study authors concluded that the float center had been poorly managed and failed to ensure adequate safeguards against pseudomonas in the float tank.
Rules on filtration SOPs are vital to keep pseudomonas in check in recreational water facilities. This includes taking measures to ensure that filtration units are not broken or undergoing maintenance when clients are placed in a float tank.
The section 5.12.10.8.1 of the Model Aquatic Health Code recommends one volumetric turnover of a floatation filtration and disinfection system at opening and four after the last user at the end of the day, as well as a minimum of three volumetric turnovers in between users.
This case also demonstrates the importance of inspections and audits of these facilities by public health authorities and/or certifiers, to address the present-day challenges of float tank operators.
