Health Effects of Swallowing Water When Swimming in Natural Bodies of Water Fact Sheet
If you plan to swim in a natural body of water like a river, lake, pond, or the ocean, it is important to keep in mind the potential health effects of swallowing the water. Awareness of what else might be floating in the water with you is the first step in knowing how to protect your health. Please do not assume that water from lakes, streams, rivers, or springs is safe to drink. Water in a stream, river, or lake may look clean, but it can still be filled with bacteria, viruses, and parasites that can result in recreational water-related illnesses. If you swallow the water while you are swimming, you can get illnesses like giardiasis (caused by the tiny parasite Giardia) or cryptosporidiosis (caused by the microscopic parasite Cryptosporidium).
How does the water become contaminated?
Two of the main sources of raw water contamination are runoff pollution and untreated sewage being released into the water. Both runoff pollution and untreated sewage contain pathogens. Pollution can also come from high concentrations of farm animals like chickens, pigs, and cows, which can contaminate local waterways with runoff that is then carried to beaches and swimming areas.
How are recreational water-related illnesses spread?
You can get recreational water-related illnesses if you swallow, have contact with, or breathe in mists or aerosols from water that is contaminated with pathogens.
What are the most common symptoms?
Diarrhea
Skin rashes
Ear pain
Cough or congestion
Eye pain
Different infections from the water and how they can be prevented
Swimmer's Ear:
One potential infection is called swimmer's ear. It is typically caused by water that stayed in the outer ear canal for a long period of time, providing a moist environment for bacteria to grow. Anyone can get swimmer’s ear but it is most often seen in children.
Signs and symptoms:
Pain when the outer ear is tugged or when pressure is put on the part of the outer ear that sticks out in front of the ear canal (tragus)
Itchiness inside the ear
Drainage from the ear
Redness and swelling in the ear
Preventing swimmer's ear:
Dry ears thoroughly after swimming
Try to keep ears as dry as possible
Do not put objects such as cotton swabs in the ear canal and do not try to remove ear wax as it helps to protect the ear canal from infection.
Diarrheal illness
Pools and hot tubs have chlorine, other chemicals, and filters that help to ensure pathogens are killed. Lakes, rivers, and streams are not chemically treated. Therefore, the chances of live pathogens being in the water are greater. Some parasites, such as Cryptosporidium and Giardia; some bacteria, such as shigella and E. coli; and viruses such as norovirus cause diarrheal illness.
Diarrheal illness is the most common recreational water-related illness. People who are already sick with diarrhea can spread it to others when they get in the water. People typically have about 0.14 grams of poop on their bodies at any given time. When a person who is sick with diarrhea gets in the water, that tiny amount of poop on their body can wash into the water around them and contaminate it with pathogens. If someone else swallows the contaminated water, they can become infected.
Signs and symptoms:
Loose or watery stool
Abdominal cramps or pain
Bloating
Nausea (upset stomach)
Urgent need to have a bowel movement
Preventing diarrheal illness:
Stay out of the water if you are sick with diarrhea (if you have cryptosporidiosis, do not go in the water until two weeks after diarrhea has completely stopped)
Do not poop in the water
Do not swallow the water (avoid putting your head underwater)
Take kids on bathroom breaks and check diapers every hour (and change diapers away from the water's edge to keep pathogens from getting in the water and, obviously, wash your hands after changing a diaper)
Shower before and after swimming
Who is at risk?
Children
Pregnant women
Immunocompromised persons
Elderly persons
This is a list of those who are most at risk when it comes to recreational water-related illnesses but anyone can get sick from the water if they swallow water that contains pathogens.
Are Pets at Risk?
Taking your dog with you to a natural body of water, such as a lake, river, or ocean, can be fun for both you and your pet. However, while it is a great way to take your pet out for fresh air and exercise, there is also the possibility of the animal being put at risk of contracting a water-borne illness or experiencing other health issues due to drinking the water. Bacteria, parasites, chemicals, and even salt can cause health problems when consumed by animals. The common name for cyanobacteria is blue-green algae and, if your pet ingests it, liver failure, vomiting, diarrhea, and even death can result. Other bacteria such as Leptospira, Salmonella, Campylobacter, and Escherichia coli can also cause severe health effects in animals. One example of a parasite of concern is Giardia. If an animal ingests the parasite Giardia, weight loss, chronic intermittent diarrhea, fatty stools, and vomiting can result. Chemicals from herbicides, pesticides, and oil can cause side effects such as vomiting, seizures, and heart problems. Even ingesting too much salt from swimming in ocean water can be dangerous for animals because it might dehydrate the animal and cause an electrolyte imbalance. The majority of the time, cases are mild. However, severe illness and death can result. Whenever your dog is swimming, it is important to keep these points in mind:
Beware of stagnant water (brain-eating amoeba are most often found in hot, stagnant water) - avoid small bodies of water that is not moving.
Watch out for cyanobacteria! Do not allow your dog to swim where cyanobacteria is present.
Bring fresh water for your dog to drink.
Dry your dog’s ears, since water in your dog’s ears can lead to ear infections. If your dog is prone to ear infections, talk to your vet about an ear cleaning solution that you could carry on your swimming trips.
Dry your dog’s fur. If you have access to fresh water, it is best to rinse your dog and then dry your dog before the trip home.
Check your dog head to tail once you are home - brush your dog and do a good head to tail check looking for any potential problems.
How to stay safe
Look for signs - Be aware of any signs indicating the beach is closed or the water is unsafe. In areas that are not monitored regularly, choose swimming sites in less developed areas with good water circulation.
Avoid swallowing the water! When waterborne pathogens are present, most swimmers are exposed when they swallow the water. You will be less likely to get sick if you swim without putting your head underwater.
If possible, shower before you enter the water and after you have finished swimming.
Wash your hands after swimming before handling food. If you bring food to the beach or wherever you are swimming, another way to protect yourself and others is by washing your hands before handling your food or food you are giving to others, to decrease the risk of ingesting contaminated food.
Take kids on bathroom breaks and check diapers every hour. If you bring your children swimming, ensure they are taking bathroom breaks so they do not have accidents in the water. If you are swimming with a baby check diapers regularly to prevent pathogens from getting into the water.
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Resources:
Centers for Disease Control and Prevention. (2021, July 7). Recreational Water Illness. https://www.cdc.gov/dotw/rwis/index.html
Law’s Country Kennel. (2019, November 28). 10 Tips for Taking Your Dog Swimming in a Lake or River. https://www.lawscountrykennel.com/fort-wayne-pet-boarding/10-tips-taking-dog-swimming-lake-river/
Mayo Clinic. (2021, August 18). Diarrhea. https://www.mayoclinic.org/diseases-conditions/diarrhea/symptoms-causes/syc-20352241
Mayo Clinic. (2021, August 13). Swimmer's ear. https://www.mayoclinic.org/diseases-conditions/swimmers-ear/symptoms-causes/syc-20351682
Minnesota Department of Health (2018, March). Recreational Water Illnesses (RWIs). https://www.health.state.mn.us/diseases/waterborne/waterborne.html
PetVet Care Centers Network. (n.d.). Has My Dog Been Poisoned? Signs & Symptoms. https://www.germantownah.com/site/blog-memphis-vet/2019/11/11/dog-poisoned-signs-symptoms
Vetstreet. (2015, June 1). Is It Safe for My Dog to Drink From Rivers, Lakes or Oceans? http://www.vetstreet.com/our-pet-experts/is-it-safe-for-my-dog-to-drink-from-rivers-lakes-or-oceans