Virtually all rivers and lakes in Switzerland are safe to swim in, in terms of water quality. Thanks to various protective measures and major advances in wastewater treatment in recent decades, the water in Swiss rivers and lakes is now very clean.
Bathing water quality is an indicator of the state of water in rivers and lakes. Microbiological testing is used to assess whether there is a health risk from bathing water. For example, water that is contaminated with pathogenic microorganisms can lead to stomach problems and diarrhoea.
Surveys by cantonal authorities
Cantonal authorities monitor the quality of bathing water in rivers and lakes. During the bathing season, they are responsible for carrying out regular checks of public bathing areas and other places by rivers and lakes that are frequently used for bathing. Checks of river and lake bathing areas are mainly based on measurements of faecal pollution indicators (E. coli, intestinal enterococci), which point to contamination by domestic wastewater or animal manure. The appearance of the water and other quality-related parameters are also taken into account.
The cantonal measurements at bathing sites, which are sampled uniformly in accordance with the EU Bathing Water Directive, are sent to the FOEN, which prepares them for longer-term, national and international assessments. These assessments are published the year following the bathing season.
National assessment of bathing water quality
The assessment of the selected bathing sites sampled in accordance with the EU Bathing Water Directive shows that the bathing water in Swiss lakes and rivers is of very good quality. More than 97% of the bathing waters assessed are of at least sufficient quality, while only a small fraction of bathing waters were classified as 'poor'. These values have been stable for years.
Survey and assessment in accordance with the EU Bathing Water Directive
Survey and assessment in accordance with the EU Bathing Water Directive
As a member country of the European Environment Agency (EEA) and the European Environment Information and Observation Network (Eionet), Switzerland participates in certain parts of the reporting required by the European Bathing Water Directive (2006/7/EC). The EU directive does not apply in Switzerland, but Swiss participation in reporting allows for international comparison and the presentation of Swiss data in EU publications.
In order to facilitate this, the FOEN analyses the data on bathing water quality in accordance with the EU directive, while the cantonal authorities often use other methods (e.g. the 1991 recommendations from the then Swiss Agency for the Environment, Forests and Landscape SAEFL). In contrast to the SAEFL method, the EU assessment requires at least four samples per bathing season and at least four years' worth of measurements. Insufficient data leads to the bathing water being classified as 'no rating possible'. In rare cases, the different assessment methods can also result in different quality classifications for the same bathing area. The public should follow the information from the cantons. The EU classification is only used for international comparison.
The methods for surveying and assessing bathing water quality in accordance with the EU directive are set out in the FOEN's enforcement aid on bathing water assessment (available in de, fr, it).
The national assessment does not include all bathing waters in Switzerland, but the additional information published by the cantonal authorities also shows that very few bathing waters are of poor quality. The ones that are of poor quality are mainly located along the large rivers of the Swiss plateau or in places near wastewater treatment plant discharges or similar facilities.
Water protection measures paying off
The various water protection measures taken in recent decades have significantly improved the state of Swiss rivers and lakes compared wtih the 1980s. Some regions built and upgraded wastewater treatment plants with an eye to improving bathing water quality for the benefit of the general public and tourism. The quality of bathing water is not directly related to the water's chemical or biological state. Nevertheless, efforts to improve bathing water quality also have a positive effect on the condition of the entire aquatic ecosystem.
Local bathing water quality
Cantons and communes inform the public about the current bathing water quality of rivers and lakes on their websites (see below). The FOEN does not have information on local bathing water quality.
Bathers should comply with the local authorities' recommendations and instructions. If the conditions for bathing are inadequate, the authorities must provide information and take measures both to protect bathers and to improve water quality. Warnings or bathing bans can be issued if necessary.
It is best to avoid bathing after heavy rainfall or during floods, as these can cause rainwater overflows from the sewage system or wash away farmyard manure and thus increase pollution by pathogenic microorganisms.
Blue-green algae and swimmer's dermatitis
Some lakes experience rapid growth of cyanobacteria, known as blue-green algae, during hot periods. The toxins produced by blue-green algae can be harmful if swallowed and also cause skin rashes, which is why local bathing bans are often issued when there is a blue-green algae bloom.
Swimmer's dermatitis, also known as duck fleas, duck itch or swimmer's itch, is a skin condition caused by the larvae of a waterfowl parasite and can occur after bathing in a warm lake. Cantonal websites provide information on what you can do to avoid swimmer's dermatitis.
The cantons, usually the cantonal medical services and the cantonal laboratories, are responsible for health issues.
Further information
Last modification 23.05.2024
