Are swimming and bathing pools or natural swimming ponds a possible source of infection for the transmission of the novel coronavirus SARS-CoV-2?
The water in conventional swimming pools (outdoor or indoor) is subject to constant treatment. Compliance with the generally accepted rules of technology offers extensive protection, even against unknown organisms and chemical substances. Filtration and disinfection are effective methods for the inactivation of registered microorganisms (e.g. bacteria and viruses). The water in baths with biological treatment does not contain any disinfectants, so there is a certain risk of infection in such baths, which the bather should generally be made aware of on site.
The morphology and chemical structure of SARS-CoV-2 is very similar to that of other corona viruses, for which studies have shown that water is not a relevant transmission route. These enveloped viruses are easier to inactivate by disinfection procedures than noroviruses or adenoviruses.
Water treatment in conventional baths
Bath visitors can transmit infectious pathogens via smear infections, through droplet infections or via direct entry into the bath water. Basically, people suffering from an acute respiratory infection or diarrhoea should not visit swimming pools in order not to endanger other bath visitors. This applies regardless of the potential pathogens involved. Regular cleaning and disinfection measures in the area around the pool and in the sanitary facilities will reduce any potential pathogens (bacteria and viruses) that may be introduced. A disinfectant (usually chlorine) is added to the pool water itself, which inactivates or kills potential pathogens introduced into the pool water. Enveloped corona viruses are particularly easy to inactivate. In conventional swimming pools, the Federal Environment Agency's recommendation "Hygiene requirements for pools and their monitoring "2 should be observed overall.
Water treatment in baths with biological treatment (Natural swimming ponds)
The water in baths with biological treatment contains no disinfectant. There, the concentration of introduced bacteria or viruses is reduced by natural cleaning and degradation processes as well as by filtration. Potential pathogens introduced therefore survive longer in the water than in a conventional bath. For baths with biological treatment, the Federal Environment Agency's recommendation "Hygienic requirements for small bathing ponds (artificial swimming and bathing pond systems) should be observed.
According to the current state of knowledge, the novel coronavirus SARS-CoV-2 is mainly transmitted via direct contact between people or contaminated surfaces. The probability of infection in swimming pools is therefore comparable to other places in public spaces. Swimming and bathing pool water in Germany is treated and disinfected in accordance with the generally recognised rules of technology. In the case of pools that are built and operated in accordance with standards, in which the water treatment corresponds to the generally recognised rules of technology and in which, in particular, the flow, treatment and operational control are carried out in accordance with standards, it can be assumed that a hygienically perfect water quality is achieved and that the swimming and bathing pool water is well protected against all viruses, including corona viruses. However, care must be taken to ensure that the cleaning and disinfection measures in the swimming pool are strictly adhered to.
Compared to conventionally treated pools, pools with biological treatment generally carry a higher risk of infection, which the bather should be made aware of on site.