Swimming water quality and blue-green algae

Environmental Services monitor the hygiene and water quality of 25 public beaches in Helsinki during the swimming season 15 June–31 August. You can check the swimming restrictions and up-to-date swimming water survey results on this page. Information on the blue-green algae status can be found online on the Outdoor Exercise Map.

On this page

Blue-green algae status and swimming water quality

The quality of swimming water is monitored throughout the swimming season.

See the blue-green algae status on the Outdoor Exercise Map service (summer season)(Link leads to external service)(Link leads to external service)

See the summer 2023 survey results on swimming water quality (pdf)

Check from the sampling plan 2023 (pdf) when the water will be sampled and at which beaches.

Why are beaches subject to swimming restrictions?

In 2023, the Helsinki Environmental Services recommended that people do not swim at the Iso Kallahti, Marjaniemi and Rastila beaches, because their water quality has been determined to be poor based on the sample results. Water samples taken at the beaches have from time to time contained elevated amounts of intestinal bacteria.

Based on the swimming water sample results, the swimming water quality at Iso Kallahti, Marjaniemi, Rastila and Pikkukoski beaches has been classified as poor in 2023. The classification is based on the logarithmic average of the sample results from the previous four swimming seasons. If the swimming water is classified as poor, the municipal health protection authority must give instructions to avoid swimming, or swimming must be prohibited at the beach in question, either temporarily or permanently, for at least one bathing season. 

The municipal health protection authority assesses and classifies the swimming water quality at each beach on the basis of the results of controls after the end of the swimming season. The classification is made only for public beaches (so-called EU beaches) where beach users are estimated to be at least 100 per day during the swimming season. The classification is not made for small public beaches. 

Blue-green algae on beaches

Almost every summer, blue-green algae, which can be poisonous, is found at beaches. The amount of blue-green algae typically increases in July when the water temperatures rise, and the blue-green algae situation can change very quickly.

Signs of blue-green algae include green water and green algae stripes visible on the beach. A small amount of blue-green algae is visible in the water as small stick- and nugget-like formations.

What to do when there is blue-green algae in the water:

  • Avoid swimming. 
  • Do not allow small children or pets into the water. Make sure that children and pets do not drink water that has blue-green algae.
  • Do not use water containing blue-green algae as washing water or sauna water.
  • If you swim or wade in water containing blue-green algae, immediately rinse your skin with clean water.

Hygiene at the beach

You can get sick at the beach if a person with a stomach disease spreads norovirus, for example. Do not go to the beach if you have symptoms of a cold or stomach disease.

Maintaining good hygiene is important at the beach as well. Wash or disinfect your hands after going to the toilet. Children’s diapers may not be changed and children’s bottoms may not be washed in the swimming water.

Do not swim if you have wounds or if the surface of your skin is otherwise broken. Bacteria enter a swimmer’s body through broken skin and can cause an infection. Swimming is not recommended for people who have a skin infection as the bacteria can spread in the water.

Report harmful water

If you suspect that swimming water has caused illness or harm, you can report the case in the Ilppa service. 

Notifications received through Ilppa are not processed on a daily basis. In case of an acute emergency, inform the lifeguard or call the emergency number 112.

Report harmful water in the Ilppa service (in Finnish)(Link leads to external service)

Please note that the Ilppa service is not for reporting algae sightings. Algae sightings can be reported in the Vesi.fi map service.

Report an algae sighting in the Vesi.fi map service (in Finnish)(Link leads to external service)

You can also find this page at hel.fi/swimmingwater.