As a dangerous winter storm pounds the South, officials in Houston and the surrounding Harris County have announced a boil water advisory.

Here’s what you need to know to stay safe:

During a boil water advisory, your community’s water might be contaminated, so you should use bottled water or boil tap water for drinking and food preparation, according to the Centers for Disease Control and Prevention.

You should boil tap water even if it’s filtered, the CDC said.

Don’t use water from appliances connected to your water line, like ice from the refrigerator, the CDC said.

Boiled or bottled water should be used for brushing your teeth.

Avoid swallowing water while showering or bathing. For babies and young children, a sponge bath will reduce the chance of them swallowing water, officials said

For hand washing, you can use tap water and soap in many situations, but the CDC urges people to follow guidance from local health officials. Hands should be washed for at least 20 seconds, the CDC said, and if water isn’t available, use a hand sanitizer that contains at least 60% alcohol.

The CDC advises using disposable plates, cups and utensils during a boil water advisory.

“Household dishwashers generally are safe to use if the water reaches a final rinse temperature of at least 150 degrees Fahrenheit (65.55°Celsius), or if the dishwater has a sanitizing cycle,” the CDC said.

To clean surfaces, use bottled water, boiled water or water that’s been disinfected with bleach, the CDC said.

It’s safe to do laundry as normal, the CDC said.