How Hygienic Are Public Swimming Pools? | Parasites & Bacteria Risks

With intestinal parasites and skin infections, health experts say public swimming pools can be, in effect, giant soups of pathogens if the water is contaminated and hygiene standards are not met.

The Most Common Pool Water Villains
For the last 25 years, the sites most associated with waterborne diseases on England and Wales have been swimming pools. The biggest threat? Cryptosporidium, a tiny parasite that can bring days of terrible stomach problems, including diarrhoea, vomiting and stomach pain.

Infected swimmers can unwittingly spread the parasite even after their symptoms subside. A study from Ohio found that adults swallowed an average of about 21 milliliters of pool water every hour, and children about 49 milliliters; those are more opportunities for infection that can be amplified in a crowded pool.

Cryptosporidium isn't the only concern. Bacterial threats like Staphylococcus, for instance, Staphylococcus, can result in skin infection, while fungal infections are known for playing havoc with wet changing rooms. Others include.

Swimmer’s ear: An outer ear infection from water that hangs around too long

Infections in the eye can lead to blindness.

Legionella: when inhaled in pool mist, can cause Legionnaires’ disease
How Pools Work Against You, and How You Can Fight Back: The Role of Chlorine
Chlorine, the primary chemical used to disinfect pools, helps keep most of these risks at bay. Originally introduced in 1903, bleach is still the first line of defense against pathogenic bacteria, including common culprits like Campylobacter, Shigella, and Salmonella as well as norovirus.

However, chlorine’s effectiveness depends on:

Good pH and alkalinity of the water
How many people use the swimming pool (more bodies = more demand for chlorine)
Frequent cleanings and working filters
Nevertheless, outbreaks can and do happen, often when chlorine levels in pools decline or equipment breaks. Regulations differ from country to country: in the UK, operators must follow existing general health and safety laws, in the US CDC’s pool safety code is not mandatory, and varies between states.
Staying Safe While Swimming
Most public pools are safe, experts stress, thanks to strict hygiene and water treatment protocols. Still, swimmers can help by:
Showering before entering the pool
Not swimming when ill, especially with diarrhoea
Not swallowing pool water
With proper attention and public awareness, pools can be a place of health, not harm.