When your home has been flooded, there’s more than just water to worry about. Flood waters ferry all the gross stuff at the bottom of storm drains, ditches, and sewer lines. When they recede, they could very well leave mud and toxic substances behind in your home.

According to the EPA, coming into contact with sewage or mold can cause allergic reactions and other problems. “You have to assume that mold is growing after a flood,” says Kellogg Schwab, Ph.D., the Abel Wolman Professor in Water and Public Health at Johns Hopkins University in Baltimore. “Mold can cause respiratory distress and can exacerbate asthma.”

To protect yourself, wear clothing that covers your arms and legs. To shield your hands and face—and to avoid breathing in mold spores and toxic fumes—the EPA recommends [PDF] wearing an N95 respirator, goggles tight enough to keep dust and small particles out of your eyes, and long, tight-fitting gloves made of rubber or neoprene. (See a list of supplies you’ll need for your cleanup below.)

Keep anyone with a weak or compromised immune system out of the house because mold, cleaning chemicals, and sewage in storm runoff can make them even more sick.

“Mold starts growing in damp places within 24 hours, and within two days, you can have visible colonies if it’s warm,” says Joan W. Bennett, Ph.D., a fungal geneticist and professor of plant biology and pathology at Rutgers University in New Brunswick, N.J.

The first step for getting rid of mold is to air out your house.

• If you have power, turn on your air conditioner, a dehumidifier, and/or every fan you own. Keep your windows closed if you have a dehumidifier and an air conditioner to help the air circulate inside and get rid of excess moisture. Keep your windows open if you have only fans, and face the exhaust toward an open window.

• If you don’t have power but you own a portable generator, use it so that you can follow the strategy above. Just remember that generators emit deadly carbon monoxide; to avert carbon monoxide poisoning, never run a generator indoors. And “make sure to place the generator at least 20 feet from your home, with the exhaust facing away from your house,” advises John Galeotafiore, associate director of product testing at Consumer Reports. If your generator isn’t connected to a transfer switch in your home, use a heavy-gauge extension cord (around 12-gauge), to keep the generator at a safe distance from your house.

• No power at all? If weather permits, open all your windows and doors to create airflow.

While you’re airing out your home, use a humidity meter, around $15 at hardware stores, to keep tabs on the moisture level. Aim for between 30 and 50 percent humidity to inhibit mold growth, the EPA advises [PDF].

Floors, walls, and furniture may be dry to the touch and still harbor mold and bacterial growth. A moisture meter, $50 at hardware stores, is another good tool to have, so you can detect dampness you can’t see.

Before you get rid of contaminated debris, be sure to put on your respirator and other protective gear.

Jeff Bishop, former director on the board of the IICRC, recommends using shovels or rakes to remove wet silt and debris from your home, and depositing it a safe distance away from your house. Just make sure to thoroughly clean and sanitize your clothes and shoes, and clean the tools with bleach after you use them.

If you have flood insurance, call your insurance company about the documentation you need to back up your claim. You may need to save pieces of carpet, flooring, and walls, and take photos of the extent of the damage. The Insurance Information Institute says some insurers may want to view your property remotely via video chat or even use drone footage to assess damage to your entire neighborhood.

If any household items, such as pieces of furniture or carpeting, have been damaged and you can’t clean and dry them within 24 to 48 hours of your house being flooded, discard them, the Centers for Disease Control and Prevention recommends. Chances are these items already harbor mold and can’t be saved. If there’s any item of value that has to be discarded, take a photo of it for your insurance claim.

Ask your town’s sanitation department about how to dispose of household items from your cleanup.

If the drywall in your home has more than 10 square feet total of water damage, the EPA recommends hiring a contractor with experience handling water damage to remove it. Any area smaller than that, however, you can deal with yourself. You’ll want to cut the drywall 15 to 24 inches above the visible water line.

“Take a utility knife, score the drywall, then punch it in,” Bishop says. Check with your local sanitation department to see whether you need to take the drywall to a dump yourself, or if you can just pile it up on your curb for trash pickup.

Then, if the insulation behind the drywall is damp, you’ll need to remove that, too. Nonporous materials, such as metal and glass, can simply be cleaned thoroughly with water and detergent and sanitized with a bleach and water solution. The CDC recommends 1 cup of bleach to 1 gallon of water to remove mold on hard surfaces.

Don’t seal any walls up with new insulation and drywall until everything is completely dry.

Even if they appear dry, ceramic tile, sheet vinyl, laminate, and solid wood floors should be removed because moisture and silt collects underneath them—and cause bacteria or mold to grow.

Once you discard these, ensure that everything is clean and dry before installing new flooring. Maintain your home’s humidity at 30 to 50 percent, and use a moisture meter to check that subflooring is at or below 16 percent moisture content before installing new flooring (for wood floors, manufacturers advise that the subfloor’s moisture content should be 13 percent or less). Be patient—it might take a few weeks for your flooring to return to a reasonable moisture content, Bishop says.

If you’re unsure when you can reinstall flooring, the EPA recommends that you consult with a contractor or home inspector who has experience with flooding (see above).

Whatever you do, don’t plug in or otherwise provide power to your appliances right away (read our article “What to Know About Water-Damaged Appliances”), because their components could be corroded or damaged by flood waters.

If an appliance, such as your washer or stove, has been submerged in flood water, Consumer Reports recommends discarding it to be safe. If you think an appliance can be saved, make sure to hire a professional repair person to inspect it before putting it back into service.

“Mold doesn’t do a great job of growing on metals or ceramics,” says Bennett, the professor of Plant Biology and Pathology at Rutgers University. However, you still want to wipe down everything with bleach to sanitize and kill any possible mold.

If there’s no visible mold, the CDC recommends using a solution of 1 cup of bleach to 5 gallons of water for cleaning most nonporous surfaces, such as the metal on appliances. If you see mold growth, use 1 cup of bleach to 1 gallon of water. Be sure to rinse or wipe items and allow them to completely air-dry before you use them.

Bishop, the former director on the board of the IICRC, emphasizes that there are a lot of scams involving restoring flood-damaged homes after disasters, so be sure that the restoration firm you hire is certified for mold and water damage remediation. (See the list of organizations recommended by the EPA, above.) Check your local government’s website to see whether there’s a department that handles flood assistance.