internal monitoring swimming pools can be challenging when it comes to choosing a measurement method, but the German swimming pool standard DGfdB R 94.04 can provide guidance. It offers detailed guidelines for hygiene inspections in public swimming pools and includes instructions for using Dipslide contact plates a testing method.
Swimming pools, public baths, and other aquatic facilities are environments where pathogens such as bacteria, viruses, and fungi can easily spread due to moisture, heat, and dirt from bathers. This makes thorough cleaning essential to minimize the risk of infection, especially since visitors are often barefoot or come into direct contact with various surfaces.
The standard’s recommendations include conducting a thorough inventory of all surfaces and areas in the swimming facility and establishing cleaning schedules. Cleaning methods, the selection of chemicals, and disinfection methods should be tailored to each surface. Cleaning equipment must be selected with care and kept in good condition. In addition, staff must receive annual training on the proper use of cleaning chemicals.
Purity Testing Using contact plates
An important part of self-monitoring is ensuring cleanliness through sampling usingcontact plates. The standard recommends pressure plates with CSA medium, such asTP Dipslides (i.e., if the focus is on testing for Pseudomonas aeruginosa), but other agar variants also work; if the purpose is solely a general cleanliness check, an agar for total count also works well. It is also possible to use a so-calledcombo plate, which hasagar for total count on one side andPseudomonas,E. coli/coliform, or Enterobacteriaceae agar on the other side. Combo plates are practical and more cost-effective to use compared to traditional single-agar contact plates testing for more than one hygiene indicator.
The standard specifies various levels of cleanliness and actions to be taken if the targets are not met. This helps the business maintain high hygiene standards and avoid health risks.
The standard describes a four-step scale for the number of bacteria (total count) as follows:
- Target value (Z) 100 cfu/100cm²(Green, Green)
- Tolerance limit (Z+1) 200 cfu/100 cm² (Green, Yellow)
- Warning threshold (Z+3) 400 cfu/100 cm² (Yellow/Orange)
- Action level (Z+7) 800 cfu/100 cm² (Orange/Red)
Of a total of 10 contact plates at least 5 contact plates show a “tolerance value” of no more thanZ+1 (i.e., 2 cfu/cm² or 20 cfu as the average of two sides, if one side measures 2 cm x 5 cm). If three samples fall within the Z+7 range (8cfu/cm² or 80 cfu as the average of two sides) ,further testing is required.
If this is not achieved, measures must be taken in accordance with the established self-monitoring plan. The extent of the measures is proportional to the results shown in the table above. In cases where growth is very high (German: sehr hoch or rasen!), the action plan will be more comprehensive.
At the bottom of the table are two rows: “Gesamtkeimzahl” translates to “total bacterial count” (non-specific bacteria). “Fäkalkeime” translates to “fecal bacteria” or “fecal coliforms.” This row should also be applicable toPseudomonas aeruginosa,even though the bacterium is not classified as a coliform. However, the standard is not entirely clear on what is meant here, and this is open to discussion. For surface cleaning inspections, we recommend using a contact plate for total bacterial count, or a combination plate if you also wish to test for coliforms, for example. Regarding the analysis ofPseudomonas aeruginosa ,however, weagree with the Public Health Agency of Sweden thatregular water sampling is sufficient.
The annex to the standard recommends conducting test prints on the following surfaces, for example:
- at least 3 pressure tests on cleaning machines/cleaning equipment
- shower room floor
- seating surfaces in wheelchairs
- walking areas in the swimming pool (floor and stairs leading down to the pool)
- seating areas in the swimming pool
- handles and handrails
- starting blocks (stools, springboards, trampolines)
- massage tables
- changing table and changing pad
- sauna door handle
- sauna floor
Documents
- GfdB R 94.04 Hygiene, Cleaning, and Disinfection in Baths (PDF, 4 MB)
- Summary of the standard in Swedish (142 KB)
- See alsothe Public Health Agency of Sweden’s general guidelines on swimming pools (HSLF-FS 2021:11)
Please contact us ifyou have any further questions.