Drinking pool water can lead to diarrhea. This results from exposure to contaminants, including microscopic organisms and chemical irritants. Biological pathogens are often the primary cause, but chemical imbalances or byproducts can also irritate the digestive system.
Microscopic Culprits in Pool Water
Microscopic pathogens are the most frequent cause of diarrhea from ingesting pool water. These include parasites like Cryptosporidium (“Crypto”) and Giardia, as well as bacteria such as E. coli. These germs typically enter the water through fecal matter from infected swimmers; even tiny amounts can introduce millions of organisms.
Cryptosporidium is concerning because it is highly resistant to chlorine. While chlorine can kill many germs within minutes, Crypto can survive in treated pool water for over seven days. Ingesting a small number of Crypto oocysts can lead to illness, with symptoms like watery diarrhea, stomach pain, nausea, vomiting, and low-grade fever appearing two to ten days after exposure.
Giardia is another parasite causing giardiasis, found in contaminated pool water. While more susceptible to chlorine than Crypto, chlorine can take around 45 minutes to inactivate Giardia. Symptoms of giardiasis, including diarrhea, abdominal cramps, gas, and nausea, usually begin about two weeks after exposure. E. coli, a bacterium linked to fecal contamination, can cause severe diarrhea and stomach cramps. Some strains can lead to more serious complications.
Chemical Factors and Irritants
Chemical imbalances and byproducts in pool water can also contribute to digestive upset. Chlorine and other disinfectants react with organic matter like sweat, urine, and dirt from swimmers to form chloramines. High levels of chloramines can irritate the eyes and respiratory system, and if ingested, can cause gastrointestinal issues.
Drinking water with elevated chloramine levels can lead to symptoms such as nausea, vomiting, and diarrhea, particularly in individuals with sensitive stomachs. The irritation arises because these chemicals can affect the digestive mucosa. While chlorine is effective at killing germs, excessive concentrations or improper pH levels can also directly irritate the gastrointestinal tract, leading to stomach discomfort. This chemical irritation is generally less common as a cause of severe diarrhea compared to pathogen-induced illness, but it can contribute to general stomach upset after swallowing pool water.
Safeguarding Your Swim
Preventing illness from pool water involves proactive measures. Avoid swallowing pool water, as this is the main route for ingesting contaminants. Showering before entering the pool helps remove dirt, sweat, and other substances that consume chlorine and reduce its effectiveness. Even a quick one-minute rinse can significantly reduce microbes introduced into the water.
It is also important to stay out of the pool if you are experiencing diarrhea. Even after symptoms resolve, some pathogens like Cryptosporidium can still be shed for up to two weeks, posing a risk to other swimmers. For young children, who are more prone to swallowing water, encouraging frequent bathroom breaks and changing swim diapers away from the poolside can help prevent contamination. Additionally, observing the pool’s condition, such as water clarity and the absence of a strong chemical smell, can indicate proper maintenance and reduced risk.
When Symptoms Arise
If diarrhea develops after swimming, manage symptoms and know when to seek medical attention. Dehydration is the primary concern, so adequate fluid intake is essential. Drink water, clear broths, or electrolyte-rich beverages like sports drinks to replace lost fluids and minerals. Rest is also important for recovery.
Seek medical care if symptoms are severe or persistent. This includes diarrhea that does not improve after 24-48 hours, signs of severe dehydration such as excessive thirst, dry mouth, reduced urination, or dizziness. Other warning signs that warrant a doctor’s visit include a high fever (over 102°F or 39°C), severe abdominal or rectal pain, or bloody or black stools. Vulnerable individuals, such as infants, young children, pregnant women, and those with weakened immune systems, should consult a healthcare provider promptly if they experience symptoms, as they are at higher risk for more serious complications.