Maybe a water line break in your community caused the water system’s pressure to drop, possibly allowing contaminants to leak in. Or maybe bacteria or other organisms that can cause illness were found in the public water supply during testing. Whatever the problem, when your community’s water system is contaminated or at risk of contamination, the public utility may issue a boil water notice. But what does that mean you should do, exactly?

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How to boil water

Boiling water is the best way to kill harmful bacteria and parasites, according to the Centers for Disease Control and Prevention (CDC). To boil water correctly:

1. Fill a pot with water.
2. Once you see a rolling boil, let it boil for 1 minute.
3. Turn off the heat, and let it cool.
4. Use the water, or put it into a clean container with a lid for future use.

When to use boiled water

The CDC says to boil water or use bottled water for:

  • Drinking
  • Making baby formula
  • Washing produce and other food
  • Brushing your teeth
  • Making coffee in a coffee pot
  • Making ice
  • Your pet’s water dish

But you don’t need to boil water for:

  • Showering, bathing or shaving — but try not to get the water in your mouth or eyes, and keep showers and baths short.
  • Washing your hands — vigorous washing with soap and tap water is safe.
  • Washing dishes or clothes — but use the sanitize setting (if there is one) on your dishwasher and washing machine.

Throw away any food, beverages or ice made with tap water before the boil water advisory went into effect.

What if you can’t boil water?

If your power’s out and you’re unable to boil water, you can disinfect it instead. If your tap water is clear (not brown), follow these steps from the CDC:

  • Add 1/8 teaspoon of unscented liquid bleach to 1 gallon of tap water
  • Mix well and wait 30 minutes before using.
  • Store the water in a clean container with a cover.

While bleach is toxic and drinking it can be deadly, it’s safe in this concentration.

If your tap water isn’t clear, filter the water through a piece of cloth first and use ¼ teaspoon of bleach instead.

What if I drank possibly contaminated water?

According to the Washington State Department of Health, the likelihood that you’ll get sick is low. Still, watch for symptoms such as diarrhea, nausea, vomiting, fever and abdominal cramps. If you have any of these, call your doctor.

Related: 15 Easy Ways to Conserve Water

Once the boil water order is lifted, clean and flush devices that may have had contact with tap water, such as your coffee pot, water dispenser and ice dispenser. Follow the directions in the owner’s manuals.

Angela is a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide. Prior to joining SafeBee, she was the features editor for Boston.com at The Boston Globe, overseeing health, travel, entertainment, business and lifestyle coverage. Before moving to features, she was the news and homepage editor, covering stories such as the Boston Marathon bombing, Red Sox World Series victories, presidential elections, a papal inauguration, and more. Her favorite safety tip: Clean your phone! The average cell phone has 18 times more germs than the toilet handle in a men’s restroom.