Never Start a Shower If You Haven't Done This First, CDC Says

Millions of Americans are infected with waterborne illnesses every year.

According to the CDC, the U.S. "has one of the safest drinking water supplies in the world," but that doesn't mean it can't harm you.

The agency reports that about 7.2 million Americans get sick every year from diseases that spread through water. Breaking this down even further, these waterborne pathogen-based illnesses result in around 601,000 emergency department visits, 118,000 hospitalizations, and a harrowing 6,300 deaths annually.

But drinking water is not the only way you can get sick from water.

There has been a recent shift in how waterborne disease is reaching people in the U.S., according to the CDC. During the first part of the 20th century, most waterborne illnesses were caused by pathogens in drinking water, and these included diseases like cholera and typhoid, which would result in serious gastrointestinal illness or even death. But "once effective and consistent drinking water treatment, disinfection, and sanitation measures were put into place across the country, these diseases became rare," the agency explains.

Now a different source is pushing a lot of these diseases: the nation's complex water systems. "Water travels further in these complex water systems because of the large number of pipes, drains, and other plumbing fixtures," the CDC says. "This makes it harder to maintain water quality and to keep enough disinfectant in the system to kill germs."

The pipes used in these systems can easily grow and collect bacteria and fungi in a slime that is referred to as biofilm—making them a home for the germs that are killing most people now. The waterborne illnesses caused by biofilm germs "are responsible for the majority of waterborne disease-related hospitalizations and deaths," the CDC warns.

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Waterborne germs can reach you through your shower.

Unfortunately, these harmful germs could be making their way to you through your shower. According to the CDC, germs inside of pipes multiple rapidly when water is sitting still for a long period of time. "When you turn on the water, particularly if water has remained stagnant in your home’s pipes for longer than normal, germs from biofilm can come out of the faucet, shower head, or other water devices," the agency explains.

Once these germs are released, they can make you sick "when the water is inhaled as a mist, comes in contact with an open wound, goes up the nose, or is splashed in your eyes while you are wearing contacts." Those most at risk for getting waterborne illness include people 50 and older or younger than six months old, as well as current or former smokers and contact lens wearers. People with a chronic lung disease, weakened immune systems, or other underling illnesses like diabetes, kidney failure, or liver failure are also at an increased risk.

"Most people may know that harmful waterborne germs can cause stomach illnesses, like vomiting or diarrhea, if they are swallowed. But these germs can also cause illnesses of the lungs, brain, eyes, or skin," the CDC warns.

You should never start a shower if you haven't done this.

You can also still be exposed even if you have a water filter system for your shower—so don't assume you're safe. "Most home water filters are not designed to remove germs from your water," the CDC warns. "They typically use a carbon filter to remove impurities like lead or to improve the taste of your water."

With that in mind, you should be aware of the CDC's most important guidance in avoiding exposure to waterborne germs through your shower—flush your shower head. According to the agency, you should never start a shower without first flushing your shower head if it's been a week or more since you last used that shower.

"Open the cold water tap fully and adjust as necessary to avoid water overflowing or splashing. The cold water should run for two minutes. Turn off the cold water and open the hot water tap fully, adjusting as necessary to avoid water overflowing or splashing. Run the water until it starts to feel hot and then turn it off," the CDC explains.

You should follow the same steps even if you have just one handle that controls both the hot and cold water. "Put the handle all the way to the 'cold' setting and run the water for two minutes; then move the handle all the way to the 'hot' setting and run the water until it starts to feel hot."