Swimming pools, beaches, lakes, and streams provide an opportunity to cool off during a summer that’s warmer than usual. Yet germs in the water can make people sick, especially young children, elderly people, and people with weak immune systems.
Germs that can cause waterborne illness include Cryptosporidium, Giardia, Shigella, E. coli, and norovirus. In the past three years, three outbreaks of waterborne illness have been reported to state health officials – two in lakes and one in a swimming pool.
“It’s important to do all we can to protect ourselves and others from waterborne diseases when we take a dip into local pools, lakes, and rivers,” said State Epidemiologist for Communicable Disease Dr. Scott Lindquist. “Stay out of the water if you’re ill or have recently had diarrhea.”
One way germs enter swimming pools and water at beaches is when people who have or recently had diarrhea get in the water. According to the U.S. Centers for Disease Control and Prevention, the average child brings 10 grams of fecal material into the pool – equivalent to the weight of four pennies. However, even microscopic amounts of feces can carry enough germs to make other people sick.
Chlorine in swimming pools kills most germs, but some types of germs can resist chlorine for many days. Also, feces or other contaminants people introduce into the water from their bodies – such as urine, sweat, and dirt – can change how chlorine works, making it less effective.
To reduce germs in water, state health officials advise people to stay out of the water when ill with diarrhea; avoid urinating and defecating in the water; and take kids on frequent bathroom breaks, checking smaller children’s diapers every hour. Showering thoroughly with soap before getting in the water is also a great way to keep swimming waters clean.
Some beaches and swimming areas are monitored by public health agencies that put up signs to warn visitors when germs are in the water. It’s important to follow instructions on all posted signs. Because germs from sewage, pets, wild animals, or other natural sources can get in the water, people should also avoid swallowing water from lakes or rivers. It’s crucial for hikers and campers who get their drinking water directly from a lake, stream, or river to boil, filter, or disinfect the water using the recommended methods.
“Diarrheal illnesses can be serious. Go see your health care provider right away if you have diarrhea that’s bloody, lasts more than five days, occurs with fever or chills, or causes you to become dehydrated,” Lindquist said. “And if two or more people become ill after swimming at the same place, report it to your local health agency to help prevent more illnesses.”
In addition to diseases from germs, water recreation can lead to skin irritations such as hot tub rash, swimmer’s itch, and swimmer’s ear. People should avoid swimming or allowing pets to play in water where there’s a visible scum; it may be a harmful algal bloom, a growing problem in Washington and the Pacific Northwest. Toxins produced by blooms can be harmful to people and animals. Check recent toxicity test results for your lake.
In addition to illness prevention, health officials want everyone to have fun in the water and to take water safety seriously. Always supervise children carefully, and make sure that everyone wears a life vest when on boats, rafts, or swimming in areas without a lifeguard. Other tips and prevention information are available on the Department of Health’s Water Recreation Safety Web page, doh.wa.gov.