Know the “Un-cool” in your Pool!

“Welcome to our _ool. Notice the absence of “p” in it. LET’S KEEP IT THAT WAY.”

Since I was a kid, this was the ubiquitous message I often came across nailed to the nearby fences, walls or the toilet doors next to the swimming pools wherever I went. A plea to keep the germs out, to keep the pristine, chlorinated pool water sparkling clean.

Is our pristine pool water really clean?

It’s pool season, the grandest of all seasons, or so you might think. Other than becoming a most sort after place for a recreational cool off on warm days, jumping in the pool also helps you stay in shape. Being a non-weight-bearing exercise, swimming utilizes most of your muscles, making it effective for both cardio and muscle endurance.

However, public swimming pools are a bowl of health risks that can infect you and your family. According to a recent report from the Centers for Disease Control and Prevention (CDC), 493 recreational waterborne disease outbreaks were reported from 2000 to 2014 — causing at least 27,219 illnesses; most of them tracing back to hotel swimming pools or hot tubs.

Germs, germs, germs

Humans aren’t the only creatures that visit swimming pools. Just like us, the germs that enjoy hanging out in the recreational water come in all shapes and sizes. They include various pathogens such as viruses (hepatitis A and norovirus), bacteria (Shigella species; the nasty E. coli O157:H7) and parasites (Cryptosporidium and Giardia). Most of these can cause a range of gastric symptoms like diarrhea, nausea, vomiting or stomach cramps.

Swimmers are at risk of respiratory infections if they breathe in steam or mist from a pool that contains the harmful bacteria Legionella. It results in flu-like symptoms and can put you at risk of Legionnaires’ disease—severe pneumonia that would probably put a damper on the rest of your summer.

Infection with the bacterium Pseudomonas or certain fungi can result in skin rashes (dermatitis, folliculitis or athlete’s foot) and swimmer’s ear (otitis externa)—an infection in the outer ear canal that can cause pain and discomfort for swimmers.

How do they get into the water?

Obviously not by leaping from the diving board or clambering down the poolside ladder. They get into the pool by hitching a ride—on us. Many of these germs spread from person to person in swimming pool water via fecal transmission—by swallowing water that’s had poo in it.

These bugs live and multiply happily in an infected person’s gastrointestinal tract and are excreted in their poo. Surprisingly, there is actually a small amount of poo on most people’s bottoms—about 0.14 grams of feces on average, according to the CDC. This poo gets washed from their skin into the water, and the contaminated water is then swallowed by other swimmers, transferring the germs to their bodies. More drastically, a baby or toddler might poo in the water (called an accidental fecal release, or AFR), small amounts of which may then be swallowed by other swimmers.

If you’re pretty sure you don’t swallow the water when you swim, a 2006 study found that, during a 45-minute swim, adults swallowed, on average, 37 milliliters—that’s almost two tablespoons. Children swallowed twice as much. Once swallowed, germs live in their new host’s gastrointestinal tract until they’re pooed out, beginning the cycle again.

The hard to kill: Cryptosporidium and Giardia

If all this has you swearing never to go in a swimming pool again, don’t worry—viruses and bacteria are controllable by proper, regular disinfection regimes, including chlorination. Of course, if there’s been an ‘AFR’ (or if someone has vomited in the water), normal disinfectant won’t be enough to keep germs under control. The contaminated area may need an extra dose of chlorine;  the pool may need to be emptied, disinfected and refilled; or the whole pool may need to be closed and superchlorinated or given a shot of ultraviolet radiation or ozone.

Nevertheless, two bugs that are fairly resistant to pool chemicals (thanks to their hard outer shells) are the single-celled parasites Cryptosporidium and Giardia—the leading cause of pool-related infestations. They’re found in the fecal matter of fellow swimmers who are infected, and the spores can survive for days to weeks or even months in water. If you’re unfortunate enough to swallow water contaminated with either, you may experience a range of symptoms including acute diarrhea, bloating, fever, nausea, and vomiting for as long as two to three weeks. It can be particularly dangerous—even fatal—in children, pregnant women, or people with a compromised immune system who are undergoing chemotherapy or have AIDS/HIV.

Cryptosporidium, in particular, is highly infectious. Just one person infected with Crypto can pass enough germs to contaminate a large pool, and you don’t need to swallow much-contaminated water to become ill. (To put some numbers on it, an infected person can shed up to 100 million Cryptosporidium germs in one bowel movement—and you only have to swallow 10 germs to get sick). 

Worried about wee?

One out of every five people going for a swim pees in the pool, says a survey conducted by the Water Quality and Health Council. It is known to contain bacteria—and particularly high levels of bacteria in people with urinary tract infections, which are fairly common. However, it’s unlikely you’ll get sick from swimming pool water that’s had wee in it as the bacteria in urine are likely to be tackled by chlorination.

Pee in your pool can cause other problems, however, which, in turn, can allow bugs to flourish. When the ammonia in urine reacts to chlorine, free chlorine is used up, contributing to the creation of chemical irritants called chloramines. Not only do chloramines reduce chlorine’s effectiveness, but they can also make us sneeze, sniffle and cough. If you’ve ever found yourself with streaming eyes or a runny nose at the pool, chloramines are probably the reason.

The strong smell which you might encounter at some pools and think of as ‘chloriney’ (germ-busting) is actually not the smell of chlorine, but of chloramines. It’s a sign that there’s a fair amount of muck (including urine and sweat) going into that pool.

Is chlorine enough to keep our swimming pools safe?

The unhealthy behavior of pool-goers has put swimmers at a whopping increase in the risk of developing recreational water illnesses (RWI). Poor practice of pool compliances, such as the lack of maintaining appropriate disinfectant and pH levels, make swimmers and, especially kids, sick.

To help protect swimmers from pathogens, proper pool maintenance is essential.

Chlorine is the most sought after disinfectant used to keep bacteria and viruses at bay. (Click here to know how). However counter to the popular belief that chlorine kills germs instantly, in fact, it actually takes different times for the same amount of chlorine to work, depending on the microorganism. Chlorine will kill bacteria such as E. coli in under a minute, but around 16 minutes to kill the hepatitis A virus. It’ll need 45 minutes to kill Giardia, and (wait for it) up to 10 days to kill Cryptosporidium. Appropriate levels of chlorine are equally important. While a higher concentration can give you an itchy rash, make your hair dry and brittle or give you red and itchy eyes; lesser amounts would be just not sufficient.

Pathogenic microorganisms can also be inactivated by other chemicals such as bromides, or physical filtration methods, such as treatment with UV radiation or ozone systems.

Also, it’s important to get the water’s pH level right (that is, how acidic or alkaline it is). It determines how much chlorine is available to kill germs. While a higher pH makes the disinfection less effective, a very low pH can corrode swimming pool’s pipes, and can (as can high pH) irritate eyes and skin. A water pH between 7.2 and 7.8 is just perfect.

If you have your own pool, you have a responsibility to maintain it so that it does not present a health hazard to those enjoying a splash.

How to avoid getting sick after a dip?

  • Swim only in well-maintained pools with clean surfaces devoid of any slimy biofilms, where pathogens like Legionella and Pseudomonas can flourish.
  • It’s also important to check facilities’ functional filtration systems, inspection scores, ask facility operators about their maintenance practices, and avoid facilities that aren’t properly maintained.
  • The most important thing is to be sure the pool is chlorinated. If you do not smell chlorine, do not get into the pool. A crowded pool means more chlorine is needed to maintain safe water chemistry. Try to go swimming in the morning and evening, when the pool is not too crowded. To help protect swimmers, facility operators should check chlorine levels regularly, especially when the facility is busy.
  • Avoid swallowing water from pools and other recreational facilities.
Shower before swim. (This one is borrowed from a poolside wall)
Shower before a swim. (This one is borrowed from a poolside wall)
We all need to pitch in our bit too for keeping germs out of the pool in the first place, by taking a few commonsense measures such as:
  • avoid swimming while sick.
  • staying out of the water for at least two weeks after the disappearance of symptoms if we’ve recently had a gastrointestinal infection or diarrhea.
  • taking small children for frequent loo breaks when using the pool.
  • using swim nappies for babies who are going in the pool, and changing them often (in the change room, not poolside).
  • using the toilet before getting inside the pool and never pee in the water.
  • having a shower before going into the pool to make sure that we wash off any dirt, excess bacteria, or even skin oils and suntan lotion, which can tie up the chlorine that’s used in pools to kill the germs. (Wearing sunscreen in the pool can actually bind the chlorine to your sunscreen, and it’s not available to kill the germs.)
  • Wear a bathing cap while in the water.

Take home message? Check out your public pools, and choose one that’s well maintained, doesn’t have a strong chlorine smell, and has showers and baby change areas. It’s also a good idea if it has a separate swimming area for babies and toddlers; lest there is an AFR, the offending pool can be emptied out and treated without affecting the main pool.

Yes, there could be something lurking in the water and the threat of illness is real, but overall as long as the pH and chlorine levels in the pool are being maintained, the disinfectants will kill off most germs that could make you ill.

We all share the water we swim in. Keep poop, pee, sweat, and dirt out of it!


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