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Health problems associated with bathing waters


Bathing waters include beaches, lakes, rivers and artificial pools such as indoor and outdoor pools and spas. Bathing waters may contain microorganisms (blue-green algae and other bacteria, viruses, parasites) or other pollutants. People can also contaminate bathing waters with their secretions, urine, feces or products such as sunscreen.

Chlorine is used for disinfection of water in pools and spas to prevent contamination with disease-causing microorganisms. However, chlorine can react with organic matter in water to produce toxic substances called ‘chloramines’. These chloramines spread in the air and give the characteristic chlorine smell of indoor pools. Chloramines can also cause irritation of the respiratory tract.

Bathing in contaminated water can cause certain health problems:

  • Swimmer's itch (skin irritation caused by contact with small larvae called ‘cercarias’, which are found in some lakes)
  • Gastroenteritis
  • Eye, ear and throat infections
  • Health problems caused by blue-green algae blooms
  • Legionellosis (an infection caused by the bacterium Legionella, which is especially prevalent in spas)


In most cases, health problems associated with bathing waters appear 24 to 48 hours after contact with contaminated water.

The following are signs and symptoms of some of these health problems:

  • For swimmer’s itch:
    • Small red spots that become swollen, similar to those of insect bites
    • Itching, which can last 1 to 2 weeks
  • For gastroenteritis:
    • Diarrhea
    • Stomach ache
    • Nausea
    • Vomiting
  • For legionellosis:
    There are 2 types of legionellosis. The benign form is called ‘Pontiac fever’. The more serious form, which is rare in Québec, is called ‘Legionnaires' disease’. The 2 forms of the disease cause different symptoms:
    • ​Symptoms of the benign form of legionellosis are similar to those of the seasonal flu
    • Legionnaires’ disease causes a lung infection (pneumonia), which generally occurs within 2 to 10 days after contact with the bacteria

When to seek medical help

Most often, you do not need to see a doctor because most of health problems associated with bathing waters heal themselves without treatment.

However, if you have symptoms that persist or worsen, call Info-Santé 811 or see a doctor. Mention that you bathed, and specify where. 


Most health problems associated with bathing waters do not require treatment.

Legionellosis must however be treated with antibiotics.


Most health problems associated with bathing waters do not result in complications.

Legionnaires' disease can, however, result in the following complications:

  • Respiratory distress
  • Acute renal failure
  • Multiple organ failure

Legionnaires' disease can also cause death in 10 to 15% of cases, depending on the age and health condition of people who catch it.

People at risk of experiencing complications

People with a weakened immune system are more at risk of experiencing complications following a health problem associated with bathing waters. 


Health problems associated with bathing waters appear especially when a person swallows contaminated water.

They may also be the result of:

  • Skin coming into contact with water contaminated, for example, by blue-green algae blooms or cercarias
  • Breathing contaminants in the surrounding air, such as chloramines or droplets containing the bacterium that causes legionellosis

Protection and prevention

No matter where you bathe, you can take some precautions. Thus, you avoid exposing yourself to microorganisms or contaminants into bathing waters or having health problems. To learn more, read the Preventing health problems associated with bathing waters page.

People at risk

Some people are more at risk of presenting health problems associated with bathing waters. They include:

  • Children
  • Seniors
  • People with chronic illnesses, especially when their immune system is weakened

Last update: June 13, 2023


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