Rodent Droppings and Nest Cleanup, the Wet Method

Why the Wet Method Matters

Mouse and rat droppings, urine and nesting material can carry several diseases. The one that shapes every cleanup rule is hantavirus, which is carried mainly by deer mice and a few other wild rodents in the United States. People are infected mostly by breathing in tiny particles from dried droppings, urine or nests that get stirred into the air. Hantavirus pulmonary syndrome is rare but serious.

That is why the CDC tells you never to sweep or vacuum droppings dry. A broom or a regular vacuum turns dry droppings into dust you then breathe. Wetting them first with a disinfectant keeps particles on the surface and kills the virus.

Rodents can also spread other illnesses. Rats can carry leptospirosis in their urine. House mice can carry lymphocytic choriomeningitis virus, which is a particular concern during pregnancy. Droppings can spread salmonella onto food and counters. The same wet method protects you from all of these.

You usually cannot tell a deer mouse from a house mouse by the droppings, so treat all rodent droppings the same way.

Mixing the Disinfectant

The CDC recommends a bleach solution of 1 part bleach to 10 parts water, or a commercial disinfectant whose label says it works against viruses. For bleach, that works out to about 1 1/2 cups of bleach in 1 gallon of water.

• Use plain, unscented household bleach that is not past its date. Bleach loses strength over time.
• Mix a fresh batch each day. Diluted bleach breaks down within about a day.
• Mix in a room with open windows, and never add ammonia, vinegar or other cleaners.
• Test on a hidden spot before spraying fabrics, carpet or wood, since bleach can discolor them. Use a labeled disinfectant for those surfaces instead.

If you use a commercial disinfectant, follow its label for dilution and contact time. Some need to stay wet longer than 5 minutes.

Get Rid of the Rodents First

Cleaning before the rodents are gone means cleaning twice. Start by trapping and sealing, then clean once activity has stopped.

• Use snap traps set along walls, where rodents travel. Bait them with a small amount of peanut butter. Check them every day.
• Poison baits inside the home can leave rodents dying in walls, where they cause odor and attract flies. Keep any bait in tamper resistant stations away from children and pets, or skip it indoors.
• Seal entry points. Mice can squeeze through gaps about a quarter inch wide, and rats through slightly larger openings. Pack small holes with steel wool and seal with caulk. Use metal flashing, hardware cloth or cement for larger gaps.
• Look where pipes and wires enter the home, under sinks, around the water heater, at garage door seals, dryer vents, and where the roof meets the walls.
• Store food, pet food and birdseed in sealed metal or thick plastic containers.

Once no new droppings have appeared for about a week, you are ready for the final cleanup.

Nests, Dead Rodents and Trapped Rodents

Nests hold a lot of urine and droppings, so they need the same care as a pile of droppings.

• Spray the nest until it is soaked through and let it sit about 5 minutes. Pick it up with paper towels or a gloved hand and put it in a plastic bag.
• For a dead rodent or one in a snap trap, spray the rodent and the trap with disinfectant and let it soak about 5 minutes. Place it in a plastic bag, seal it, and put that bag inside a second bag. Throw it in a covered outdoor trash can.
• Snap traps can be reused after disinfecting, or you can throw the whole trap away.
• Never pick up a live or dead rodent with bare hands.

If a rodent died inside a wall or ceiling and you cannot reach it, the smell usually fades in a few weeks. A pest control company can sometimes locate and remove it through a small opening.

Cleaning Furniture, Fabrics and Food Areas

After the droppings are gone, clean anything the rodents may have touched.

• Counters, cabinets, drawers and floors. Wash with detergent, then wipe or mop with the bleach solution or disinfectant.
• Upholstered furniture and carpet. After removing droppings with the wet method, steam clean or shampoo them.
• Bedding and clothing. Wash in hot water with laundry detergent and machine dry on high heat.
• Books and papers that cannot be cleaned with liquid can be left outside in sunlight for several hours, or set aside in a rodent free place for about a week, before handling with gloves.
• Food. Throw away any food in packaging that was chewed or had droppings on it. Wash and disinfect sealed cans and jars before opening.

Do not forget heating ducts and vents. If you see droppings inside a duct, do not run the system until a professional cleans it, because the fan can move particles through the house.

When This Becomes a Professional Job

The CDC gives extra precautions for heavy infestations and for buildings that have been closed up, such as cabins, sheds and barns. Those settings can have high amounts of dried material, and a cleanup there needs more protection than gloves and a spray bottle.

Call a professional when you see any of the following.

• Droppings spread across an attic, crawlspace or large part of a garage.
• Droppings and nesting in attic insulation. Soaking insulation in bleach does not work well, so contaminated insulation is usually vacuumed out with HEPA equipment and replaced.
• A cabin, shed or outbuilding that has been closed for months with obvious rodent activity.
• Rodent droppings inside heating or cooling ducts.
• A home where someone has been diagnosed with hantavirus.

A qualified crew wears respirators with HEPA filters, disposable coveralls and eye protection, seals the work area, and removes contaminated materials in sealed bags. Ask how they will protect the rest of the home and how they will dispose of the waste.

See a doctor if you develop fever, fatigue and muscle aches in the weeks after cleaning up rodent droppings, especially if you then have coughing or trouble breathing. Tell the doctor about the rodent exposure. Symptoms of hantavirus usually start between one and eight weeks after exposure.

Step by Step

1. Trap and Seal First

   Set snap traps and close gaps with steel wool and sealant. Wait until you stop seeing new droppings before the final cleanup.

2. Air Out the Space

   Open doors and windows and leave the area for at least 30 minutes before you start. In a closed shed or cabin, air it out longer.

3. Put On Gloves

   Wear rubber, latex, vinyl or nitrile gloves. An N95 respirator and safety glasses add protection in small, dusty spaces.

4. Mix Fresh Bleach Solution

   Mix 1 part bleach to 10 parts water, about 1 1/2 cups of bleach per gallon. Or use an EPA registered disinfectant labeled for viruses.

5. Soak the Droppings

   Spray droppings, urine spots and nests until they are fully wet. Let them soak about 5 minutes, or as long as the disinfectant label says.

6. Wipe Up With Paper Towels

   Pick up the soaked droppings with paper towels and put them in a plastic bag. Do not sweep, brush or vacuum.

7. Disinfect the Whole Area

   Wash the surface with detergent, then mop or wipe with the bleach solution. Clean nearby counters, cabinets and floors the rodents may have crossed.

8. Bag and Dispose

   Seal the bag, place it inside a second bag, and put it in a covered outdoor trash can.

9. Clean Up Yourself

   Wash your gloved hands in disinfectant or soap and water, then remove the gloves. Wash your bare hands with soap and warm water.

Mistakes That Make It Worse

• Sweeping or vacuuming droppings before soaking them, which puts dried particles into the air you breathe.
• Spraying and wiping right away. The solution needs about 5 minutes of contact to work.
• Using old bleach or a bleach mix made days earlier, which may be too weak to disinfect.
• Cleaning without first stopping the rodents, so fresh droppings return within days.
• Using a shop vacuum without a HEPA filter in an attic full of droppings. It blows fine dust straight out the exhaust.

Where You Live Matters