After a flood or water damage: cleaning, drying, and using EM against odors

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A basement flooded after a storm, a leak that has soaked a floor, a river that has overflowed its banks and invaded the ground floor: after the water come the mud, the dampness, and, very quickly, a stubborn smell of silt and mildew. Effective microorganisms are sometimes used to reduce these odors during the cleanup.

They can help, but only in their proper place, which is at the very end. Before them come safety, cleaning, and, above all, drying. This guide walks you through it step by step, without promising anything EM can't do.

Safety first

• Electricity: don't turn the power back on in a flooded room until an electrician has checked the wiring. Never touch any electrical appliance while standing in water.
• Gas and heating: have your furnace or boiler and any gas appliances that got wet inspected. Never use a generator, a gas-powered pump, or a fuel-burning space heater indoors: carbon monoxide is invisible, odorless, and deadly.
• Contaminated water: floodwater is almost always dirty, and sometimes mixed with sewage or petroleum products. Wear boots, waterproof gloves, long sleeves and pants, goggles, and a mask, and wash your hands often.
• Vulnerable people: keep children away from the work area. If you have asthma or allergies, avoid doing the cleanup yourself.
• Tap water: water from the public system remains safe to use unless your local authorities or water utility advise otherwise. Water from a flooded private well should be considered unsafe to drink until it has been tested.

Think about your insurance before throwing anything away

Photograph the rooms, furniture, and damaged items before taking them out, and keep your receipts. Report the damage to your insurer as soon as possible: notification deadlines depend on your policy and the rules where you live, so check your contract.

Remove, clean, dry

Remove the water and mud

Get rid of standing water and then the mud as quickly as possible. Throw away all food that has come into contact with the water, including jars and damaged cans, as well as medications and toiletries.

Sort the materials

Porous materials that have been soaked generally can't be saved: carpet, drywall, insulation, particleboard, mattresses, cushions, stuffed animals, books. They stay damp deep inside and become breeding grounds for mold. Hard surfaces, on the other hand, can be cleaned: tile, concrete, metal, glass, plastic, solid wood.

Clean hard surfaces

Wash them with clean hot water and an all-purpose cleaner, scrubbing with a brush, then rinse. If the water was mixed with sewage, or for items that go in the mouth (dishes, toys), follow the disinfection guidelines provided by your local authorities or health department. EM does not replace this step.

Dry, above all dry

This is the crucial step. Mold takes hold when materials stay wet: ideally, dry them out within 48 hours. Open everything up, create cross-drafts, and use fans and a dehumidifier. A small, inexpensive hygrometer lets you keep track of indoor humidity: aim for below 50–60%.

Key takeaways

After a flood, the order matters: safety, removal, sorting, cleaning, drying. EM only comes in at the end, for odors, and never in place of any of these steps.

Using EM against odors

Once the mud is gone and the surfaces have been washed, a muddy smell may linger in walls, bare floors, or corners. This is where EM can be useful, by steering the breakdown of the last organic residues toward fermentation rather than rot.

Dilution

The manufacturer recommends diluting Microferm EM-A Active Solution at 1 to 10%: in practice, about 1 quart (1 liter) in a watering can holding 2.6–4 gallons (10–15 liters) of non-chlorinated water. Spray it on the surfaces the water reached, after cleaning, and repeat as often as needed. As with every use of EM, it's better to apply more often than to increase the dose.

To wash hard surfaces during the cleanup, you can also use EM Clean multi-purpose cleaner, at the dilutions given in our guide Natural cleaning with EM Clean.

Three precautions

• Never right after bleach. If you have disinfected, rinse with clean water and wait until everything is dry. Bleach kills microorganisms, and mixing it with an acidic product such as EM releases a toxic gas.
• Spray a fine mist, don't drench. Each application puts a little moisture back into the room: a light misting in a well-ventilated room won't slow down the drying. Heavy soaking will.
• Use non-chlorinated water for dilution, and only mix what you'll use that day. The other rules are gathered in our guide Getting started with EM.

Emy's tip

Open doors and windows for a good hour after each spraying. Moving air carries away the moisture you've just added, and there's nothing to be gained by closing up a damp room.

Let's be honest: using EM after a flood is based mainly on users' experience and the manufacturer's advice. No independent study has measured its effect in a flood-damaged home. EM does not make a home sanitary, does not replace disinfection when it's needed, and does not get rid of mold. If the smell persists despite thorough drying, look for material that is still damp or for hidden mold. For everyday odors, see also our guide Banishing bad odors with EM.

Mold: when to call in a professional

Despite all your efforts, mold may appear in the weeks that follow. The signs: a musty, earthy, or basement-like smell, black, green, or white spots, wallpaper that bubbles or peels.

• Small patches, covering less than about 11 sq ft (1 m²): you can handle them yourself. Wear a respirator mask, gloves, and goggles, clean with detergent, rinse, and dry quickly. Throw away any affected porous materials.
• Larger areas, mold that keeps coming back, or a vulnerable person in the home: call in a mold remediation company, and track down the source of the moisture.

Mold can cause or worsen coughing, irritation, allergies, and asthma. If you have symptoms, see your doctor.

Did you know?

A musty smell is often the first sign of invisible mold, hidden behind furniture, under flooring, or inside walls. Your nose detects the problem long before your eyes do.

Yard, vegetable garden, and septic tank after a flood

• In the vegetable garden, don't eat any vegetable, fruit, or herb that was submerged or splashed by floodwater, even cooked: the water may have carried sewage, petroleum products, or other pollutants, and washing isn't enough. Pull up these plants and throw them in the trash, without composting them. Then let the soil drain before working it again, so you don't compact it. The usual precautionary guidelines: wait at least two months before reseeding or replanting vegetables, and allow about three months between the water receding and the first harvest, or even four for root vegetables and crops that touch the ground. Wear gloves, wash your tools and hands, and leave your boots and gardening clothes outside. If you're unsure what was in the water, check with your local authorities.
• The septic tank: a flooded tank can be thrown off balance or filled with silt. Have it inspected, and pumped if necessary, before returning to normal use. No product replaces this inspection, as we explain in our guide Septic tanks, drains, and composting toilets.

In summary

After a flood or water damage, the priorities are safety, insurance, removing the water and mud, sorting out porous materials, cleaning, and, above all, drying quickly, ideally within 48 hours. EM only comes in at the end: about 1 quart (1 liter) of Microferm in a 2.6–4 gallon (10–15 liter) watering can, in fine, repeated sprayings on cleaned surfaces, to reduce muddy odors, never right after bleach. EM does not make a home sanitary and does not treat mold: beyond about 11 sq ft (1 m²) of mold, call in a professional.

Related products

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