After a Leak or Flood: Drying Out Within 48 Hours

Health Canada’s guide to moisture and mould lists plumbing leaks and weather flooding as moisture sources, alongside condensation on cold surfaces like windows. After a leak or flood, Health Canada’s key number is 48 hours: your house and furnishings are less likely to grow mould if they’re dried within that time.

Safety first

Health Canada says to avoid electrical shock: shut off power to the flooded area at the breaker box, and ask your local electrical utility for help if needed. Wear rubber boots while standing in water, and keep extension cords out of it. The federal Floods – Get prepared page adds a limit: don’t try to shut off electricity if any water is present. If the main power wasn’t turned off before the flood, don’t go back in until a qualified electrician says it’s safe. Don’t return home until authorities say it’s safe.

If the water may contain sewage, Health Canada says to contact your local public health department. Sewage cleanup needs extra precautions and more thorough disinfection. Children, pregnant women and people with respiratory problems should never handle sewage-contaminated water or materials. Health Canada also says to have a working carbon monoxide alarm while drying out the house, and never to use fuel-powered equipment designed for outdoor use indoors. For gear, Health Canada lists disposable gloves, an N95 mask and goggles.

Health Canada’s steps

1. Remove standing water with pumps or pails, then a wet/dry shop vacuum.
2. Remove soaked and dirty materials, debris and leftover mud. Throw out water-soaked flooring. Remove finished walls completely if the water was several feet high, or the walls were wet or humid for 48 hours or more (per the 2021 infographic).
3. Clean walls and furnishings with unscented soap and water. Health Canada notes that bleach isn’t needed to clean up mould.
4. Throw out what can’t be dried. The mould guide names carpets, sofas, cushions, mattresses, pillows, stuffed toys and bedding that have been wet. It says a mouldy mattress can’t be properly cleaned.
5. Dry. Ventilate and dehumidify until the house is dry, keeping indoor humidity between 30% and 50%. If the outdoor air is dry and mild, open doors and windows and use fans. If it isn’t, or drying is slow, use a dehumidifier and empty its pan regularly or drain it.
6. Vacuum dried surfaces with a HEPA vacuum.

Using the windows and a hygrometer

Health Canada’s mould guide treats condensation on cold surfaces, or RH above 50%, as the cue to run a dehumidifier. Our suggestion (not Health Canada’s): put a hygrometer in the affected room so you can see when it’s back in the 30–50% range instead of guessing.

Health Canada says you can usually clean small and medium mould areas yourself. It recommends a qualified professional for any single patch larger than 3 m², for floods involving sewage-contaminated water, and when water has got into wall, ceiling or floor cavities.

Sources: Health Canada, Flood cleanup: keep in mind indoor air quality; Health Canada, Infographic: Flood clean up and indoor air quality; Health Canada, Guide to addressing moisture and mould indoors; Government of Canada, Floods – Get prepared.

Originally published at https://dry-glass-notes.surge.sh/articles/drying-out-after-leak-or-flood-48-hours.html (AI-assisted, sources cited). If this helped, zaps go to hollisvarrow3753@coinos.io.