Is it really cleaner to swim in a pool or the lake?
Warning: This article contains numerous references to poop, pee, and other bodily functions. If you’re grossed out by the topic, you may prefer to read our recent post on why you should tote an "I am Lake Ontario" tote bag."
Underwater swimming. (Photo by Dave Robertson.)
After learning about the possibility of contracting illnesses and infections from a trip to the beach, many people ask us if it “safer” to swim in pools.
Waterkeeper’s expertise focuses on natural waterways such as lakes, rivers, and ponds so we turned to the experts at the Centre for Disease Control (CDC).
Recreational water illnesses (RWIs) are caused by swallowing, breathing in mist, or having other contact with contaminated water in both treated and untreated water. RWIs include a wide variety and severity of illnesses and infections including gastrointestinal, skin, ear, respiratory, and eye infections.
What is treated water?
This is water that is disinfected with chlorine to kill and oxidize harmful bacteria and germs.
Swimming pools, hot tubs, water parks, spas, and splash pads all use treated water.
There is a common misconception that chlorine begins working immediately. In reality, it takes about an hour for chlorine to kill the bacteria that can make you sick. In fact, parasites like Cryptosporidium can live in a chlorinated pool for as long as 10 days. Therefore, it should come as no surprise that Cryptosporidium is the number one bacteria that causes RWI and is the top cause of people getting sick in treated waters.
How do bacteria, parasites and viruses get in the water?
From people.
40% of people don’t shower before going swimming. So chances are you are swimming in someone else’s perspiration, lotions, and fecal matter.
The CDC estimates that, on average, people have about 0.14 grams of feces on their bodies which can contaminate pool water. And a study done by the CDC in 2013 found that one in eight public swimming pools in the United States, violated public health and safety protocols.
Even if you showered in the morning, this doesn’t mean you are clean. Chances are you have gone to the bathroom at least once throughout the day. When people enter pools without showering, their bacteria, sweat, and lotions interact with the chlorine, and ultimately render it less effective.
Additionally, when chlorine mixes with our bodies organic matter it can create a more toxic agent called halogenated by-products (HBPs) which are not good to breathe in. Even if you are just going swimming in a friend’s backyard you should shower beforehand, since bacteria doesn’t know the difference between a public or private pool. As the CDC notes “the pool is only as clean as we are.”
Fun Fact: Be aware of strong chlorine smelling pools as a well-chlorinated pool should have little odour.
What about untreated water?
Marine and freshwater beaches, lakes, rivers, and ponds can be contaminated with a number of things. Bacteria, chemicals, and other pollutants from sewage bypasses, combined sewer overflows, human and animal feces, urban runoff – can all pollute and contaminate waterways.
Along with sweat, lotions, and sunscreen, you can also bring in trace levels of fecal matter and associated pathogens into the water. Keep in mind, the water in lakes and rivers are not disinfected by chlorine. Swallowing even a small amount of water contaminated with feces can make you sick.
According to the U.S. Environmental Protection Agency (EPA), an estimated 3.5 million people get sick each year after swimming in natural water bodies containing harmful bacteria and pollution.
You are most at risk after rainfall, swimming at posted beaches, and swimming near sewer outfalls, wastewater treatment plants, and the mouths of rivers and creeks.
Healthy swimming starts with us. Keep the pee, poop, sweat, and dirt out of the water!
Here are some tips to keep yourself and others from getting sick from enjoying a day at the pool or the lake.
- Stay out of the water if you have diarrhea
If you have diarrhea and go swimming you can give diarrhea to others. In fact, diarrhea is the leading cause of illness among swimmers.
- Shower before you get in the water
Showering before going into the water is not a suggestion. IT IS A MUST. Again, the pool is undeniably only as clean as you are. Showering before stepping into the lake is also important. You should also shower after swimming to wash off any contaminants you may have come in contact with.
- Don’t pee or poop in the water
This one should be a given. Urine and feces, your body’s biowaste, belong in the toilet.
- Don’t swallow the water
Over the course of 45 minutes of swimming the average adult will swallow 16 ml (about a tablespoon) of water. Children swallow about 37 ml (2.5 tablespoons) of water. It only takes a sip of contaminated water to make you sick.
Regardless of where you decide to jump in, the bottom line is we are all responsible for the waters we play in. So let’s do what we can to ensure we’re doing all we can to protect the people who are in the water with us. After all, what’s good for the environment is really good for us too.