RIVM provides recommendations and conducts scientific research in swimming pools (bathing establishments).

Laws and regulations

The ability to swim and bathe in safe, hygienic conditions has been a source of specific government concern for several decades. To address that issue, the Act on Hygiene and Safety in Swimming Facilities was adopted in 1969; this law did not come into force until 1984 and has been amended and supplemented many times since its establishment. In 2000 its scope was extended and the name was changed to the Bathing Establishments and Swimming Facilities (Hygiene and Safety) Act (Whvbz). Together with the Bathing Establishments and Swimming Facilities (Hygiene and Safety) Decree (Bhvbz), this law regulates hygiene and safety in swimming pools. The provinces are the competent authority that enforces this legislation. A revised version of the legislation is currently under review, which will be incorporated into the Environmental Planning Act in the long term.

Research to substantiate law and regulations

To support the upcoming changes in the relevant decree, RIVM worked in conjunction with experts from the field to provide expert, evidence-based advice to various types of bathing facilities. The advice included recommendations for water quality parameters (including frequency of measurement and standard values) as well as the analysis methods to use in assessing water quality.

RIVM conducts research on water quality in swimming ponds in the Netherlands. These data are used to substantiate the proposed water quality parameters and standard values for this type of bathing facility. The results of the study are expected by the end of 2017.

  • Also see statutory requirements for water in swimming pools

Pseudomonas aeruginosa found on pool toys and teaching resources in swimming pools

Swimming pools are hot and humid; that is the perfect environment for growing various micro-organisms, such as the bacteria Pseudomonas aeruginosa.

RIVM researched the presence of P. aeruginosa on pool toys and teaching materials in swimming pools and found the bacteria everywhere. Inflatable and non-inflatable resources made from slick plastic or canvas, such as obstacle courses, floating devices and floating mats were more often contaminated than foam pool toys and teaching resources, such as swimming belts, arm floats and aqua belts. That might be due to the different methods used to store these resources and how often they are used, but it is also related to the type of plastic that was used to manufacture them. One thing was clear: when pool toys and teaching resources are put into storage while wet, there is a risk that P. aeruginosa will grow on these materials. When human skin comes into contact with contaminated toys and resources, it is possible to develop an infection caused by this bacteria, resulting in skin problems. RIVM therefore recommends that these materials are stored in such a way that they can dry properly after use. If this is not possible, for instance in the case of large inflatable objects, it is necessary to clean them thoroughly with water and soap before they are used again.

Fungal presence in swimming pools

Because fungi are omnipresent in the environment, RIVM, IHE Delft, Westerdijk Fungal Biodiversity Institute (previously KNAW Central Agency for Fungal Cultures) and Utrecht University conducted a pilot study to determine the quantities and types of fungi found in a typical Dutch swimming pool.

For that purpose, the researchers collected a large number of samples from the water in the swimming pools and from the surfaces around the pools and in the changing rooms. In total, 16 surface swabs and 6 water samples were tested by placing them on a combination of various culture media, allowing any fungi present in the sample to grow. The cultured fungi were identified by genetic analysis.

Fungi were found at most of the swimming pool locations that were sampled. The numbers varied per location: high concentrations in the water of the recreational pool and on the surface of foam playing materials, but low concentrations on a starting block, benches in the swimming hall and the changing rooms, and on the walls. The cultured fungi included various types and groups of fungi, some of which have on occasion caused infections in people, as evidenced by international research papers.

In other words, despite regular cleaning and disinfection with chlorine, fungi were still present at many places in the swimming pool. That did not come as a surprise since most of these fungi are omnipresent in the environment and do not cause infections in people. However, the presence of fungi that might cause an infection, especially in places where people walk barefoot, is not acceptable.

For that reason, the researchers planned an extensive follow-up study at multiple Dutch swimming pools in summer 2017. The focus here is on the following questions: are the fungi in different swimming pools found at the same types of locations? And are there any correlations between different cleaning regimes and the types and quantities of fungi present? The aim is to provide advice measures people can take to reduce the presence of fungi in swimming pools. The results of the research are expected by late 2017 or early 2018.