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Health problems associated with bathing waters

Description

Bathing waters include waters in natural environments (beaches, lakes, rivers) and artificial pools such as indoor and outdoor pools and spas. All bathing waters may contain microorganisms (blue-green algae and other bacteria, viruses, parasites) or other pollutants, depending on the bathing spot. 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.

Health problems associated with bathing waters

Health problems associated with bathing waters mainly appear when a person swallows contaminated water. Some microbes can cause gastroenteritis.

Health problems can also be caused:

  • when the body comes into contact with contaminated water. This can cause infections or irritation
  • when a person breathes in contaminants in the surrounding air

In pools and spas

Bathers are the main source of microbes and organic matter in the water (feces, sweat, urine, skin products, such as cream).

To avoid microbial diseases, the water in pools and spas must be filtered and disinfected with chlorine (or bromine). The water quality of public pools and spas must be tested and meet standards to protect health.

Chlorine can react with organic matter in the water and produce toxic substances called “chloramines”. Chloramines spread in the air and cause the characteristic chlorine smell of indoor pools.

A large quantity of chloramines can cause irritation (eyes, skin or airways).

Legionella bacteria can grow in poorly maintained spas, end up in the air and cause legionellosis (lung infection).

In natural environments (beaches, rivers, lakes)

There are many potential sources of pollution by microbes or other contaminants. The quality of the water is often unknown and can change quickly. Rain events can alter water quality for at least the next 24 hours.

Be vigilant when bathing and doing certain water activities. More cases of drowning occur in natural environments.

In addition, aquatic activities in natural environments can cause:

  • swimmer's itch caused by contact with cercariae, small larvae found in some lakes
  • health problems caused by blue-green algae blooms

Symptoms

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

The main health problems are:

Swimmer’s itch

The main symptoms of swimmer's itch are:

  • small red spots that become swollen, similar to those of insect bites
  • itching which can last 1 to 2 weeks

Gastroenteritis

The main symptoms of gastroenteritis are:

  • Diarrhea
  • Stomach ache
  • Nausea
  • Vomiting

Legionellosis

There are two types of legionellosis:

  • the benign form called ‘Pontiac fever’, the symptoms resemble flu symptoms
  • the more serious form, Legionnaires' disease, which leads to a lung infection (pneumonia) and usually occurs 2 to 10 days after contact with Legionella bacteria​

People at risk of developing complications

Some people are more at risk of developing health problems related to bathing waters:

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

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.

Complications

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.

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.

Last update: June 18, 2026

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