Swimming water quality and blue-green algae

Environmental Services monitor the hygiene and water quality of 26 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)

See the summer 2024 survey results on swimming water quality (pdf)

Check from the sampling plan 2024 (pdf) when the water will be sampled and at which beaches.

Why are beaches subject to swimming restrictions?

Swimming not recommended at beaches along the Vantaa River during heavy rain

The City of Helsinki Environmental Services recommend that you avoid swimming at the Pikkukoski, Pakila and Tapaninvainio beaches during heavily rainy weather. It has been observed that water quality temporarily becomes worse at these beaches along the Vantaa River during heavy rain. This is due to surface run-off and rainwater. Rainfall in the entire catchment area of the Vantaa River affects the water quality at the beaches along the river. The swimming restrictions aim to protect swimmers from potential health hazards.

Water quality at Marjaniemi beach improved

In the previous years, swimming at Marjaniemi beach has been restricted due to poor water quality. However, analysis from the 2023 swimming season showed that the water quality has improved, and the swimming restrictions are no longer in place.

We carried out surveys and corrective measures in cooperation with various operators: A cruciform joint of a property's stormwater and sewage pipelines was found and repaired along the Mustapuro brook located close by, on the east side of Ring Road I. The sewage pipeline along the brook was also replaced.
The measures reduced the risk of water contamination so that we no longer need to take the results from previous years into account when classifying the water quality. Instead, the determination of water quality will begin with the data from 2024.

Even in Marjaniemi beach, heavy rain may temporarily make the water quality worse. More information on the water quality risks at Marjaniemi beach is available in the Marjaniemi beach profile (PDF, in Finnish).

The municipal health authority assesses and classifies the water quality at each beach based on the quality control results at the end of the swimming season. The classification is only done for the public 'EU' beaches that have at least a hundred swimmers per day during the swimming season. The classification does not apply to small public beaches. For example, of the beaches along the Vantaa River, only Pikkukoski beach is an 'EU beach,' and it is classified as 'poor.'

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.