This is what happens to your body when you swallow water in the pool

It's summer, it's very hot, and swimming in the pool is a favorite activity for the whole family, especially for children. In Spain, these common recreational areas with water are typically disinfected with chlorine (although some substitute it with salt), a condition that is checked frequently and, in theory, protects us from bacteria and microorganisms.

But this is only theoretical, since the chlorine in swimming pools and the chemicals used to make the water crystal clear don't completely eliminate certain bacteria, which become resistant and silently threaten us without us even realizing it. If we swallow water, we compromise our digestive health due to bacteria, chlorine, and other bacteria. What can happen to us?

"It's okay, I just swallowed a little water in the pool."

This phrase, which we've all been able to utter at some point in our lives, actually carries far more risks than we might expect. Indeed, the chlorine and chemicals used in the pools we all swim in keep the water clean and free of (some) parasites ... but not all!

Obviously, swallowing a little water shouldn't have serious consequences, but it all depends on the bacteria and microorganisms present in the water , which chlorine can't kill. Even chlorine itself, when ingested, can cause unwanted discomfort.

If the intake was very small, we shouldn't worry, but we should watch out for symptoms related to stomach upset, such as vomiting or diarrhea, after a few hours. Normally, the consequences aren't immediate; they take hours to take effect. However, swallowing a large amount of water should get our attention and that of a doctor, just in case.

This is what happens to your body if you swallow water in the pool.

As we explained earlier, there are a number of bacteria that chlorine cannot eliminate and that can enter our bodies when we swallow pool water. Escherichia coli, Giardia, Shigella, and Cryptosporidium are microorganisms that are particularly immune to the effects of chlorine.

For those wondering where these parasites come from, they should know that they are not naturally present in the water, but rather come from fecal matter and end up being passed into the pool water imperceptibly by swimmers who have had a gastrointestinal illness and have not fully recovered. This doesn't mean that they defecate in the water, but rather that traces remain in their bodies, which can become part of the pool.

In fact, research conducted by the University of Arizona in the United States establishes that the amount of fecal matter we could all "carry on us" if we inadvertently enter a pool is 0.14 grams.

What are the symptoms if we swallow infected water?

If you ingest these microscopic fecal remains, and others associated with urine, symptoms could range from unexplained digestive discomfort to vomiting, diarrhea (with or without blood), and abdominal cramps. When in doubt, the best option is always to see a doctor to stop any germs from spreading.

In addition to the bacteria that could enter our bodies by swallowing water that is never 100 percent disinfected in the pools where many people swim, there is also the possibility of contamination by ingesting chlorine itself.

In large amounts, this chemical (chlorine) can cause burning in the mouth, sore throat, and swelling , as well as stomach problems, higher than normal blood pressure, acid in the blood, and, in severe cases, difficulty breathing. Dry drowning occurs when a small amount of water enters the lungs, causing respiratory spasms.

References

Gerba, CP 'Assessment of Enteric Pathogen Shedding by Bathers during Recreational Activity and its Impact on Water Quality'. Quantitative Microbiology 2, 55–68 (2000). Consulted online at https://link.springer.com/article/10.1023/A:1010000230103 on July 20, 2025.