Cleaning Up Your House After A Flood
NOTE: This publication was last revised in 2008. For more current information, please
refer to the Government of Canada's Get Prepared Web site: http://
Canada Mortgage and Housing Corporation (CMHC) has
been Canada’s national housing agency for more than 60 years.
Together with other housing stakeholders, we help ensure that
Canada maintains one of the best housing systems in the
world. We are committed to helping Canadians access a wide
choice of quality, affordable homes, while making vibrant,
healthy communities and cities a reality across the country.
For more information, visit our website at
You can also reach us by phone at 1-800-668-2642 or
by fax at 1-800-245-9274.
Outside Canada call 613-748-2003 or fax to 613-748-2016.
Canada Mortgage and Housing Corporation supports the
Government of Canada policy on access to information
for people with disabilities. If you wish to obtain this
publication in alternative formats, call 1-800-668-2642.
CMHC Project Manager:
Dr. Virginia Salares, Senior Researcher, Housing Technology
This second edition of Cleaning Up Your House After a Flood is
revised and adapted from the first edition written by Jim White of
CMHC offers a wide range of housing information.
Turn to the last page for a listing of related publications.
Cette publication est aussi disponible en français sous le titre :
Nettoyer sa maison après une inondation (61283)
Canadian Cataloguing in Publication Data
Main entry under title:
Cleaning up your house after a flood
Issued also in French under title : Nettoyer sa maison
après une inondation.
ISBN 978-0-660-15449-7
Cat. no. NH15-98/1994E
1. Dwellings — Moisture — Handbooks, manuals, etc.
2. Floods — Health aspects — Handbooks, manuals, etc.
3. Dampness in buildings — Handbooks, maunals, etc.
4. Indoor air pollution — Health aspects — Handbooks, manuals, etc.
5. Housing and health — Handbooks, manuals, etc.
Canada Mortgage and Housing Corporation.
RA577.5C53 1994
© 1994, Canada Mortgage and Housing Corporation
ISBN 0-660-15449-7
Cat. no. NH15-98/1994E
Revised: 2005, 2007, 2008
Reprinted: 1995, 2005, 2008
Printed in Canada
Produced by CMHC
Research into the problems produced by flooding and inadequate
clean-up is in its early stages. This document provides the best
information available at this time.
Neither the authors nor Canada Mortgage and Housing Corporation
intend any of the suggestions in this publication as medical advice.
For specific health advice on possible and suspected problems from
exposure to flooded housing, consult a medical specialist with current
expertise in this area.
For serious house problems, consult a suitably trained renovator or
professional who specializes in flood clean-up and has been recently
retrained. Knowledge is changing rapidly. The Corporation assumes
no liability for any damage, injury, or expense that may be incurred as
a result of the use of this publication.
Quick start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Flood problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Sewage—contaminated water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Molds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Contamination of water supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
The importance of time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Safety and personal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Examining the house . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Taking action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
First steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Insurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Get rid of the water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Remove wetted materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Washing down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Cleaning materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Drying things out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Cleaning the house . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Floors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Flooded floors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
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Floors that were not flooded . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Carpets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Carpets on floors that were flooded . . . . . . . . . . . . . . . . . . . . . . 18
Carpets on floors that weren’t flooded. . . . . . . . . . . . . . . . . . . . . 19
Walls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Inside wall and floor cavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Wet Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Ceilings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Appliances and electrical equipment . . . . . . . . . . . . . . . . . . . . . . . . 23
Lights, fixtures and wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Furnaces and water heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Ducting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Plumbing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Floor and footing drains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
What to throw out, what to save . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Furniture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Beds and bedding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Clothes, other fabrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Paper and paper goods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Freeze-drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Legal documents and valuable papers . . . . . . . . . . . . . . . . . . . . . 30
Thinking ahead—Preventing future damage . . . . . . . . . . . . . . . . . . 33
Appendix A—Selecting a dehumidifier . . . . . . . . . . . . . . . . . . . . . . 35
Further reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
CMHC publications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
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Contact your insurance agent as soon as possible. If your insurance
policy covers flood damage, record the damage on film, videotape or
DVD. Find out if your policy includes clean-up costs and if your
insurance company will arrange with a contractor to do the clean up.
If your insurance policy does not cover flooding, start the clean up
yourself by pumping out standing water. Make sure that your
utilities—electricity and gas—are disconnected and the flooded area
is safe before entering it.
Hose down affected surfaces with water to remove as much debris
as possible.
Remove items and furnishings from the flooded area. Scrap
difficult-to-clean materials.
Remove and discard wetted building materials.
Continue hosing down, spraying a detergent solution on soiled
surfaces to make removal easier. Use stiff brushes or scrubbers to
loosen debris from surfaces.
Rinse thoroughly with water.
If there is sewage contamination, repeat scrubbing with detergent
and water and rinse again. Use trisodium phosplate (TSP) to clean
stubborn stains on concrete surfaces.
Caution: TSP is corrosive. Do not allow it to contact skin and eyes.
Continue pumping until all water is drained.
Dry all surfaces as quickly as possible.
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Microscopic, single-celled organisms that can cause
health effects on people.
Chemical or physical agents that kill or inactivate
Dehumidifier A device that removes humidity from the air in an
enclosed inside space.
A chemical liquid that destroys germs, including mold.
A sheet of gypsum covered by paper. Drywall is used
to finish interior walls.
Pertaining to solid body waste.
Micro-organisms that dissolve nutrients from the materials
they live on and damage the host materials. Molds, yeasts
and mushrooms belong to the kingdom of fungi.
A type of biocide that inactivates fungi or fungal spores.
HEPA filter
High-Efficiency Particulate Air filter, used in air purifiers
and high-end vacuum cleaners to trap the tiny particles
in the air.
Device used to measure humidity in the air.
A microscopic organism. In Cleaning up your house
after a flood, a fungus, bacteria or mold spore.
Sensors or meters to measure moisture content of
wood (available at suppliers of woodworking tools).
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A fungus that grows on or in damp organic materials.
A simple and disposable mask that can remove
95 per cent of particles that are 0.3 microns (a micron
is one-millionth of a metre) or larger.
P100 filters
Highly efficient, oil-proof particulate filters used with
half-face or full-face respirators.
The ratio of water vapour in the air to the quantity
of vapour that would be present if the air were fully saturated.
The reproductive cells of fungi.
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flood is any event that seriously wets materials. Cleaning up your
house after a flood will help you repair water damage caused to your
home and its contents by plumbing leaks, major spills,
flooding or sewer back-ups.
Your basement is the part of the house that is most vulnerable to flooding.
Cleaning up your house after a flood starts with cleaning flooded basements and
then moves on to the rest of the house.
Leaks, spills, floods and backups cause materials to become damp, wet or
saturated and open them to attack from microbes, such as molds, bacteria
or other organisms. Microbes can cause structural decay. More important,
they can threaten the health of the people cleaning up or the occupants of
the flooded house. There can be serious health effects.
Not all problems with wet materials are alike. Some are more severe than
others, depending on the nature and the amount of material that has
become wet and how saturated that material has become.
Time is very important. All materials are likely to become moldy if they are
not dried quickly.
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Before you start the clean up, it is important to determine if the flood
involves relatively clean water or sewage-contaminated water.
You must take special precautions if your house is flooded with sewage.
There is a very real and significant danger of infection from breathing the
air in an area contaminated by sewage and from handling water and
materials contaminated by sewage.
Treat every bit of material as though it were seriously contaminated. Do
not try to save carpets, clothing and bedding that have been
exposed to sewage. Even after their surfaces are dry, they can carry
bacteria that can cause infection from breathing airborne particles or
through direct physical contact.
People with cuts or open sores, people with respiratory problems
and pregnant women should never handle water and materials
contaminated by sewage.
Contact your local health department if you suspect sewage contamination.
Follow your health department’s advice carefully.
Put sewage-contaminated waste in heavy-duty bags and tag the bags
as sewage waste immediately. Follow local regulations for disposal.
Molds grow on surfaces that are not dried quickly. For most household
surfaces, it takes one or two days for mold to start growing. By the time you
get back into your house after a flood, mold may have already started
growing. The best you can do is clean up.
The secret to preventing mold problems is to clean and dry all wet surfaces
as quickly as possible—within hours of the flooding.
Drinking water is tested to ensure that it does not contain fecal coliform
bacteria. The same tests are necessary after a clean up, to ensure that water
in and around a house is clean and not a health danger. Follow the advice
of your health authority.
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There is one, all-important piece of advice: Act quickly.
n warm, wet, nutrient-rich, food-rich conditions, bacteria need only
hours to multiply by hundreds, then thousands. Some molds start to
grow within days of flooding and show luxuriant growth within a
week. Rapid cleaning and drying are essential to slow their growth.
If possible, remove water within minutes or hours. Many materials, such
as drywall, insulation, furniture cushions, wood and paper, can draw
water above the high-water mark of the flooding. Water moves more
slowly in dense materials, but it can eventually soak up into all materials.
Time is the enemy.
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Make sure that your utilities—electricity and gas—are disconnected and
the flooded area is safe before entering a flooded area.
You need high rubber boots and long rubber gloves. You should
wear a respirator, especially if the water is contaminated with
sewage or mold is growing.
A respirator protects you from inhaling fine droplets of water or dust that
may contain bacteria. There are three different types of respirators, each
with its own advantages and disadvantages:
1. A N95 respirator is the minimum protection that you should use. It
is disposable and should be changed every few hours or sooner
if it becomes soiled or wet. Respirators with a N95 rating remove
95 per cent of particles 0.3 microns or larger. Ordinary masks screen
large particles but may not be effective in removing finer particles.
2. If you can see mist or dust, wear a half-face, dust-mist respirator
equipped with a P100 filter. For maximum protection, ask your safety
supply store to ensure that your respirator fits well. Beards cause
problems with fit.
3. In very poor conditions, such as a sewer backup, health authorities
may recommend a full-face respirator. They are hot and uncomfortable
and may limit the amount of work you can do, but they may prevent
serious infection that could have worse consequences, so wear them for
your own protection.
The Canadian Standards Association (CSA) publishes standards for
respirators. CSA Z94.4-02, Selection, Use and Care of Respirators, is
available by contacting CSA Standard Sales at
[email protected]
by calling toll-free 1 800 463-6727
by going to the CSA website at
Selection, Use and Care of Respirators has important information about using
a respirator in risky situations or for lengthy periods.
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The following questions will assist you in determining how to proceed:
1. How much water is in the basement?
Is the water a few inches, a foot or up to the ceiling? It may be possible to
drain a small amount of water manually but a large amount of water
requires a professional to drain it. If the ceiling got wet, watch that it does
not collapse on you.
2. Is the flood water contaminated with sewage?
Sewage—contaminated water—requires much more careful and thorough
cleaning than uncontaminated flood water. Materials and appliances
soaked by contaminated water may need to be thrown out. If standing
water is cloudy or smells foul, assume that bacteria have grown and deal
with it as if it is contaminated water. If the flooding brings mud into your
house, you must rinse your house thoroughly to remove it.
3. Has mold started to grow?
Failure to act quickly and remove flood water results in mold growth.
If you can smell mold when you enter your house or if you can see mold in
your house, your cleaning must include removing the mold. Clean-up
procedures for mold in houses, published by CMHC, tells you how to clean
up mold.
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ontact your insurance agent as soon as possible. Your insurance
policy may pay the clean-up costs and your insurance company
may even choose a contractor to do the work.
Photograph, film or videotape the damage as soon as you can safely enter
the flooded part of your house. Do this even if your insurance policy covers all
costs—the insurance company may want a record of the damage. If your
insurance company does not pay for flood damage, you will need a record
of the damage if you decide to take legal action.
Get rid of the water
The first and most important job after a flood is getting rid of the water.
Prompt action is of greatest importance, whether you have insurance
coverage or not. Find contractors who specialize in removing water in the
business pages of your telephone book, under “flood damage restoration”
or “water damage restoration.”
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Contractors and septic tank cleaning services have the equipment to draw
water out of your house more rapidly than you can. They can deal with the
water and hose down dirt that sticks to floors, walls and furnishings. You
may need them more than once—first to remove the flood water and again
when you do a more thorough cleaning.
Small amounts of water can be removed manually using pails or buckets—
an option when you cannot get someone with a pump.
Remove wetted materials
It is important to remove water-damaged material from your house quickly to
make it easier to clean and dry your house.
Take all material contaminated with sewage out of your house as soon as
possible. Appliances and upholstered furniture are not recoverable. Tag
these as contaminated waste to prevent others from picking these up and
re-using them. Contact your municipality to find out how to dispose of
contaminated material.
Move clothing and bedding to the outside and decide how to clean and
dispose of cloth materials once they are outside. Put paper, books and other
materials into tagged plastic containers and move them outside, to a garage
or shed. Cleaning of many items is either labour-intensive, very difficult or
impossible. This is the time to throw away things you can part with.
Identify the materials you want to keep and which should be given priority for
Remove wetted carpets and dismantle raised-floor assemblies in the
basement. Tag sewage-contaminated materials for disposal in landfill. Even
if the flood water was relatively clean, it is unlikely that wall-to-wall carpets
can be cleaned sufficiently well or worth recovering. The exception is
valuable area rugs that you can send out for professional cleaning.
Open up finished walls, cutting several feet above the waterline. High
humidity can make wall cavities damp and they can become moldy. Even
if walls seem to be dry, check—particularly if water has been left standing
for several days. You must expose hidden surfaces for cleaning.
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Remove finished walls completely if:
• the water level was several feet high;
• it took many days or longer before the water was drained; or
• the area was very humid for a prolonged period.
Examine acoustical tiles closely even if they were not wetted, since they
absorb moisture when they are exposed to humid conditions.
Washing down
Remove the worst of the dirt by hosing down the surfaces. For large areas,
use a hose with a detergent attachment—available at hardware stores and
garden centres. For smaller areas, use a spray bottle to spray detergent on
the soiled areas to make it easier to remove dirt.
When you have removed most of the dirt, check again to see what else must
be removed or opened up for further examination.
Clean surfaces by scrubbing with detergent and water. Follow by rinsing. If
sewage came in, you may want to repeat the process as many times as you
feel will get the surfaces clean.
Drain the water. If necessary, you may need to have a contractor to pump
the water again.
Chemical disinfectants, fungicides or microbial biocides are not
recommended. Chlorine bleach is no longer recommended.
The only cleaning material you need is dishwashing or all-purpose liquid
detergent. Select an unscented detergent, since perfumed detergents can
mask the odours that tell you there is a lingering or new problem.
Scrubbing with water and detergent and then rinsing should eliminate
bacteria from surfaces. There is no need for a disinfectant or biocide. If you
think that repeat washing and rinsing is not making an item clean enough,
perhaps you should throw the material out.
Concrete surfaces with stubborn stains or grease that are not removed using
dishwashing detergent can be cleaned with TSP.
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“Trisodium phosphate” (TSP) is a very aggressive compound. It is often
used to clean concrete or badly soiled paint. TSP is corrosive—it will burn
and sting. Wear gloves and goggles when using TSP. Follow the manufacturer’s
mixing instructions and sponge TSP on to the surface.
Use TSP very, very carefully and rinse well.
Do not use chlorine bleach
Chlorine bleach is a five per cent sodium hypochlorite solution.
In the past, it was recommended for cleaning up mold.
Now, Health Canada, CMHC and other agencies no longer
recommend using chlorine bleach to clean up mold.
Drying things out
Once you have cleaned a material, you must dry it as completely and as
quickly as you can to prevent mold and bacteria from growing. Rapid
removal of water is needed before things can dry out.
First remove as much water from the surface of materials as you can:
• Use squeegees, mops or cloth.
• You can also use a wet-dry vacuum or shop vacuum. These vacuums
get more water off surfaces and out of materials after you have rinsed
them than any other method.
Because of their power and ruggedness, they can get big jobs done
more quickly.
Wet-dry and industrial vacuums may have attachments that make it
easier to vacuum hard-to-get-at places. When work is completed,
clean the vacuum thoroughly.
The final drying can be done in several ways, each with advantages
and disadvantages.
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Requires little energy. It is
important to generate rapid
airflow within each space and
to remove enough air to get the
evaporated water outdoors as
quickly as possible.
Must be enough natural
ventilation in the house.
Can be very slow, especially in
damp or muggy weather.
If outside temperature is close to
freezing, add heat while ventilating
(see the caution about upper
temperature limits under
“Heaters” in this table).
Make drying faster when
outdoor air is dry and not
too cold.
In damp, muggy weather, the
air coming into the house is
already loaded with water vapour
and must be heated before it
can remove much water (see the
caution about upper temperature
limits under “Heaters” in this
Together with mechanical fans,
heaters help in drying in cold
Do not heat air to more than
35ºC (95ºF)—air that warm can
distort wood furniture and trim.
Combustion heaters—oil,
propane or natural gas—produce
water vapour and add moisture
to indoor air if they are not vented.
Dehumidifiers Use less electricity than heaters Choose dehumidifiers that work
for the same drying effect—you even at low temperatures.
get more drying for each watt of
electricity with a dehumidifier.
Test whether drying with outside air using mechanical fans is fast enough
by measuring the relative humidity before you run the fans and again an
hour later. If unchanged, you may have to provide supplemental heat or use
dehumidifiers. You may need more than one unit. See Appendix A—
“Selecting a dehumidifier,” page 35.
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Flooded floors
o prepare floors for cleaning, move removable floor coverings and
furniture outdoors. Move wet carpets and other sponge-like materials
off floors as soon as possible, so that the floor does not start to
distort or delaminate—damage that will dramatically increase repair costs.
• Remove and discard carpets that were flooded with sewage.
See “Carpets” on page 12.
• Flooded solid wood or laminate floors are unlikely to be salvageable.
• Dismantle and remove sleeper floors (raised floor on basement slab).
Don’t save particleboard, plywood or oriented strand board (OSB)
that has been soaked or wetted. Re-using it can create future problems.
• Ceramic tiles can lift and loosen. Contaminated water can seep
under ceramic titles, even if they aren’t loose. Consult a professional
tile layer.
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• Floor coverings on concrete—vinyl, linoleum and other materials—
raise two questions:
• Have they lifted and created pockets of dirt and water?
• Will the pockets prevent rapid drying?
If the answer to either question is “Yes,” remove the floor covering
and throw it out. Flooded vinyl tiles on a subfloor delay drying of
the subfloor. You have to remove them and throw them out.
Treat each case as unique and examine the situation carefully before you
decide what to do. Sometimes upper-level wet floors can successfully dry
downwards toward a removed or missing ceiling below, but they are likely
to buckle when dried that way. Fixing a buckled floor is more trouble and
more expensive than scrapping floor tiles or sheet flooring.
Floors that were not flooded
Examine main floor subfloors and floor joists that did not get flooded, but
were exposed to high humidity, for mold growth.
The best way to remove mold from the surface of wooden boards (for
example, main floor joists) is sanding with a vacuum-sander. Simultaneous
vacuuming and sanding minimizes dispersal of dusts and mold spores.
You can clean mold on the underside of a main floor from the basement
with unscented detergent and water and then rinsing with a damp rag.
Avoid getting the wood wet. The top surface of a subfloor can be cleaned
in the same way. Dry subfloors quickly.
After cleaning the subfloor, vacuum it thoroughly with a HEPA vacuum
cleaner or central vacuum that exhausts outside.
Carpets on floors that were flooded
Throw out a carpet in a basement flooded with sewage-contaminated
water. Even if the water has no sewage, it may not be worth saving the
carpet—particularly if the carpet has been under water for more than a day.
You cannot save carpet underpads. Remove them and throw them out.
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You may be able to save very expensive carpets. Move rare and expensive
carpets and rugs outdoors. If heavily soiled, rinse both sides several times.
Contact a professional carpet cleaner about what to do next.
The cleaner may suggest only simple, preliminary drying measures to
reduce shrinking and fading. Usually, you have to wrap the carpets and rugs
in heavy plastic and get them to the cleaner. Getting them to the cleaner
rapidly is vital, as you and the cleaner are in a race against deterioration
from dirt and microbes as well as water damage.
Carpets on floors that weren’t flooded
Evaluate carpets on upper floors based on how long they were subjected to
humid conditions. Odour is a useful indicator. A musty or stale odour
indicates that microbes have started to grow. You may need professional
cleaning help to get these cleaned. It may not be possible to clean severely
affected carpets.
This advice is not necessary if only the floor has been flooded for just a few
minutes with relatively clean water. However, you may have to remove
baseboards and mouldings to check for trapped dirt and water.
Clean walls as soon as possible to prevent the growth of microbes that
could cause health problems for workers or occupants.
Answering the question of how far above the flood line a wall should be
opened depends on how much water there was and how long it took
to remove the water and dry the wall. If the water was drained quickly
(within hours) and drying started immediately, opening the wall a few feet
above the flood line may be sufficient. If the flood water stood for longer
than a day, you will have to remove the walls completely.
Break open wet walls and walls that have absorbed water above the flood
line so you can clean the interior cavities. Do not rebuild the wall until the
area is completely dry.
Clean all walls in a flooded house, even those on floors above the flood line,
because they have been exposed to excessive humidity long enough to start
mold growth. This growth is often difficult to see without special instruments
and techniques. Don’t assume that surfaces are all right because they are one
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floor above the obvious problem zone. Clean with unscented detergent and
water, using a sponge or rag, and rinse with a clean, wet rag. Avoid getting the
walls too wet.
Inside wall and floor cavities
When flooding puts water inside walls and the cavities between ceilings and
floors, hidden materials usually become waterlogged and contaminated.
Too often, contaminated cavities are left closed. These cavities must be
opened and thoroughly cleaned and dried.
If you suspect that a cavity has become wet, probe or open it to find out if
it actually is wet. Soon after the main flood water is removed, drill small
holes near the bottom of cavities for drainage Later, use moisture probes or
check drillings for dampness. Whenever you find wet material in a cavity,
open it for cleaning and drying.
Empty the cavity of insulation, debris or dirt, and dry all interior materials. If
wood structural members are saturated, it may take days or weeks for them
to dry completely and you can close the cavity again. The more quickly you
open hidden spaces, the less water saturation there will be and the faster
materials can be dried to safe levels.
Wet insulation
Fibrous insulation materials (such as glass fibre, mineral wool and cellulose)
don’t have to be wet to pick up contamination. In a flood, their surfaces can
pick up large amounts of contamination and trap it. If fibrous insulation
materials stay wet for extended periods, molds and other microbes can grow.
Fibrous insulation also loses its insulation capabilities even after drying, so
you must replace it.
Board insulation, such as Styrofoam™ and urethane, can also become
saturated. It takes longer for urethane and extruded Styrofoam to become
saturated than bead-board Styrofoam. The safest action is to remove and
replace these materials unless you are absolutely sure they are not trapping
water or dirt.
Given enough time, all insulation materials will wick water up above the
high-water mark. That rising damp region can reach half a metre (1 to 2 ft.)
in a few days under some conditions. That’s why you should remove
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insulation above the obvious high-water mark and replace it with new
material once the cavity materials dry sufficiently.
Clean and dry cavities to the same standard—or higher—that you set for
other surfaces and materials. If you don’t, once you close the cavities,
problems will remain unseen and not fixed until they become severe.
Even if ceilings seem to be reasonably dry and undamaged, you should still
check them. Water can wick up walls and around corners into ceiling
materials. Check the condition of drywall and plaster to ensure that water
or damp have not saturated the core materials beneath the surface. If they
are saturated, replace them.
Carefully clean ceilings that are only damp at the surface to remove a thin
film of mold that might have grown when the air was very wet or muggy.
Good spring-cleaning practices should be enough. Dry rapidly, of course.
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Your electric utility may have advice and suggestions for
cleaning up after a flood. Check with your utility first.
on’t go into a flooded area of your house until the electricity has
been shut off and your electric utility says it is safe.
Do not use electrical equipment—outlets, switch boxes, fuse or breaker
panels and appliances—until it has been inspected and passed as safe by your
electrical utility or an electrician approved by the utility. They are not safe
when they are wet and dirty. Wet dirt is an excellent conductor of electricity
and could either short-out the power or leave some surfaces live and dangerous.
After rinsing small appliances, send them to a repair shop—being sure to tell
the repair shop that they have been flooded. If there is sewage contamination,
cleaning and repair may not make sense—repairs may cost more than they
are worth.
When the electricity is off—and only when it is off—wash and rinse electrical
outlets and switch boxes. Be sure that all electrical supply materials and
equipment are perfectly clean and dry before power is turned on again. Wet
floors conduct electricity well, so be careful.
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If larger appliances—washing machines, clothes dryers, dishwashers and so
on—were completely or partly under water, don’t use them until they are
repaired and cleaned. Water and dirt in motors and switches can cause
severe damage—and electrical shock. Be sure to tell the repair shop about
any known or suspected contamination.
Have your clothes washer and dryer repaired first so you can get a fast start
on cleaning clothing—but only if a day-or-two turnaround is possible.
Otherwise, find another way to clean and dry your clothing.
Light fixtures and sockets left dirty after a flood can cause shocks and
equipment damage. Dirt can get into surprisingly small spaces that can stay
wet for a long time when room air can’t dry the space.
Once the power is off, or after you have disconnected your lamps, take
them apart and check for dirt and damp. Do the same with your ceiling
fixtures after you have taken them down. Clean and dry thoroughly before
use. Expect some burnt-out bulbs and cracked or broken bulbs. Some
apparently good bulbs will shatter when they are turned on, so get a shade
between you and the bulb for the first trial.
If you were flooded in the spring, fall or winter, you will need heat to help
dry your house. In the summer, your air conditioner can help dehumidify
your house until you can put industrial dehumidifiers in your house.
You will need heat or air conditioning as soon as possible.
Don’t use flooded furnaces, water heaters or air conditioners until a trained
repair person has certified them as safe to use.
Have the furnace blower motor and all the many switches and controls inside
a typical furnace replaced. Sometimes, to get heat going quickly, the service
person will replace your furnace with an overhauled one with a similar rating.
After servicing, check the inside of the furnace case to make sure it is as
clean and dry as other surfaces in your house. In the days and weeks after
flooding, replace the furnace filter often—using a medium efficiency filter,
such as a pleated paper filter.
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Flooding can make the glass fibre that insulates water heaters soggy and
saturated. If that is the case, remove it and have it replaced. The insulation
may dry, but it could be badly contaminated with whatever was in the flood
waters and you don’t need that indoors forever.
Do not use hot water on most materials, since hot water sets stains from
many of the contaminants (including clays) in flood water. Cold water will
do just fine, although barely-warm water will aid drying slightly.
Clean ducts wetted by flooding until they shine.
Dirt routinely collects in forced-air heating ducts in most houses. Once
they have been flooded, they are wet as well. Have them carefully cleaned
and inspected. This is no time to guess that ducts are really clean. Check
and be sure.
Ducts are much cleaner after they are taken apart and reassembled than if
they are cleaned with a vacuum hose. Choose a contractor who can do the
job properly.
Return duct pans, which are nailed to the bottom of floor joists, are not
particularly airtight and are less airtight if joists have been wetted and dried
again. Have them taken down, clean them and re-install them, making sure
that they are installed with crimps and sealing gaskets that will keep them
airtight and quieter.
This is also a good time to seal ducting leaks, which will cut your heating
costs and make your house more comfortable.
A flood can reverse water pressure in plumbing pipes and contaminate the
water in hot and cold pipes. Have a plumber flush your plumbing pipes.
Consult your health authority. Normal use of water afterward should keep
the pipes clean and well-flushed.
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Floor and footing drains
A flood can drive water up through floor drains and sump holes and bring
materials into a house that should never be there. As the water goes down,
it can suck or wash indoor materials into drainage systems. The materials
can either partly block the drains or just sit in the drains and rot.
For health reasons, carefully flush floor drains and sump pits. You may have
to scrub surfaces to remove greasy dirt and grime that can release pollutants
into the indoor air.
The footing drains outside your foundations may have seen more water and
dirt than they could cope with during the flood. Have a qualified
plumber—preferably one specializing in drainage—check them out.
Drains can often be cleaned with special clean-out pipes or from the
connection to the storm sewer. If they cannot, you may have problems
in the spring or very rainy periods, when they will not drain as well as
they should.
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any materials can’t be cleaned and dried. It may be impossible
to thoroughly clean plush furniture, magazines and books, beds
and fluffy bedding such as duvets and comforters. It will usually
take days to get them dry, even in the best of conditions. Conditions for
drying may not be very good just after a flood, when the air is saturated and
cold, or when electrical power and heating fuel are scarce.
Immediately throw out inexpensive possessions that have been soaked.
Don’t waste time on them—there are so many other important things to do.
It is likely that cheap particleboard furniture will be unusable, so don’t try
to save it. Save antique or solid wood furniture instead.
Get regular broadloom and underpad out the door as soon as possible.
With them may go piles of dirt and thousands of litres of water, making
cleaning and drying much easier.
Save only very expensive carpets and rugs.
Throw out wet glass-fibre, mineral-wool and cellulose-fibre insulation as
soon as possible. Even when dried, these types of insulation will never insulate
well again. They can also support extensive mold growth for years and cause
serious health problems.
Don’t try to save electrical equipment that has been inundated or water-filled.
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Furniture may be difficult or almost impossible to clean if it is upholstered or
if sewage or other organic materials are involved. Antiques may be worth the
expensive treatment it takes to remove sewage or organic debris. Other upholstered
furniture is not worth the effort. Be sure to tell the restorers that there is
sewage contamination. Move fast and follow their instructions to the letter.
Particleboard furniture is probably not worth the work and expense it takes
to save it, unless the dunking was short and there is no apparent swelling.
In that case, rinse well and then dry rapidly, but not in the sun or with
direct heat. Both can cause warping. Watch carefully and slow down the
drying process (by temporarily covering furniture) if surfaces show distress
or warping starts. Open drawers to speed drying, but do not fully disassemble
them, because of possible distortion.
Clean good-quality wood furniture with detergent and water, rinsing with
a clean, wet cloth, then place it where it can get good ventilation, away
from the sun and direct heat. Again, leave drawers or other movable parts
open but in place, and slow the drying process at the first sign of warping
or distress. If necessary, apply surface waxes to slow drying of outside
surfaces and allow inside ones to catch up. Professional care may be the best
for better-quality items. Decide quickly.
Do not save mattresses and box springs. They are too difficult to clean and dry.
Wash bedding several times to get it clean. Then rinse and carefully dry.
Air-drying in a power dryer may be the best way to minimize damage. If
there is no power, carefully remove most water by pressing fragile items and
wringing fabrics that are more robust. Hang over several lines to distribute
the weight of the wet item over several supports. This should reduce
stretching. Drying outside in the sun has the added benefit of disinfecting
with ultraviolet light.
Pillows cannot be safely cleaned and dried. Throw flood-damaged pillows
out. They almost certainly have dangerous bacteria or molds.
Speed is of the essence with bedding. If it is not possible to clean it
thoroughly within hours of water damage, rinse and dry it quickly and go
back when you have the time.
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Only experts can clean contaminated silks and woollens. Some decorative
cottons are also at risk. Send these materials to a professional right away.
Ask for an estimate before agreeing to a cleaning bill. Warn the cleaner if
sewage contaminated the fabric.
Dry clean non-washable clothes that were above the high-waterline if they
are otherwise serviceable. This should remove smells.
Scrape off heavy dirt and thoroughly rinse washable clothes as soon as
possible, then wash them several times. After rinsing, dry these clothes as
rapidly as you can without risking shrinkage. Do not use much heat—only
what is needed for rapid drying.
It may not be worth the time and effort to clean some clothing. Throw it
out, or save it until you salvage items that are more valuable.
Store cleaned clothes in an area that you have carefully cleaned and dried
well. This space should be closed off from uncleaned spaces in your house.
Most paper items saturated by flood waters are not worth the time, energy
and effort it takes to save them. First, identify valuable materials. Then
focus on items that are not as wet and worth saving. Finally, get to the
soaked items of lesser value.
When you dry paper you want to keep it pressed to prevent wrinkling. You
can’t do both at the same time.
Start by getting most of the water out of the paper. To do this, place the wet
paper on blank, dry paper or thin, blotting material. Some experts recommend
lightly sprinkling baking soda on the wet paper to help change surface
chemistry and deter mold growth. However, there is a chance that any
chemical will affect the inks and change the paper’s chemistry. Test a spot
to see if there are any dramatic effects before you use a chemical on your
valuable paper goods.
Opening books to the breeze and the sun may speed drying. Remember to
close and press them at night, or more often if wrinkling starts to appear.
Drying too rapidly may damage bindings; so be cautious. Getting paper
dry quickly is important, but so is preventing damage.
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Paper that is kept together wet for days may blend into an unsalvageable,
solid mass. Act quickly.
If you cannot take the time to deal with wet paper goods in the first day or
so, wrap and freeze them until you can get to them. Rinse off as much of
the dirt as possible and towel-dry by blotting, not rubbing. If there is
sewage contamination, wrap materials carefully in freezer bags and clean
off the outside of the bags before freezing. Because of the high risk of
contamination, never mix those bags with food bags.
If you can use a freezer for wet paper only, it may be best to leave items
unwrapped or lightly wrapped, as they will dry slightly during storage.
Expert restorers use this technique, in combination with a vacuum, to
remove water from extremely valuable documents.
Later, remove items one or two at a time and carefully thaw and dry. Again,
you have to find a balance between drying too rapidly and too slowly. If
paper is dried too slowly, mold will grow; if too rapidly, bindings may
distort and pages wrinkle.
After the task is over, clean and disinfect all surfaces, especially those that
will come in contact with food. Consider all surfaces contaminated until
they have been thoroughly cleaned and dried.
Legal documents and valuable papers
Some documents are valuable for legal or financial reasons. Others have
important sentimental value.
Make every attempt to clean and dry valuable papers using the previous
instructions. Saving documents through such efforts will be less costly than
paying to replace them.
If it is clear that there is mold damage or the possibility of severe distortion,
focus on saving the information, not the paper.
Some documents can be preserved if true copies are notarized. The damaged
originals can then be destroyed and the certified copies preserved. Check
with a lawyer to determine which documents you can preserve this way.
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You can replace other documents, such as birth certificates, marriage
certificates, citizenship certificates, passports and other official government
documents. Check with local government offices to find out what to do.
Certain large documents can be substantially preserved if pressed through
hot rollers at a copy house that makes blueprints, if you can find one. This
could be worthwhile for maps or other large documents that are worth
keeping. The cost may not be high, but the paper will have to be
roll-pressed before it has dried, so act quickly.
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omeowners who have gone through a flood in their basement are
very aware of the time and work needed to deal with the damage.
Causes of flooding range from failure of municipal infrastructure to
drainage deficiencies in individual houses. There are no simple or one-sizefits-all solutions. Preventing basement flooding can include solutions in
individual dwellings, neighbourhood or subdivision measures and major
municipal and regional system protection measures.
Check the priming of the floor drains. Find a way to ensure that water stays
in these drains, so that sewer gases cannot move up into the house when
the drains dry out. If you do not have a flush line installed, be sure to check
the drains regularly, pouring some water into them to keep them primed.
Check your lot drainage, extending downspouts to lead rainwater away
from the house, improving perimeter drainage and installing backwater
prevention valves. See CMHC’s About Your House “Avoiding Basement
Change how you use your basement if you have been flooded before. Do
not store materials on the floor or against basement walls. Store as little as
possible in your basement—stored material is a liability when it gets wet.
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When you refinish your basement, consider not having a carpet. It is preferable
to keep the concrete floor bare. You can use an area rug over painted
concrete. You can take an area rug outside and clean it thoroughly,
something you cannot do with wall-to-wall carpet.
Also consider not installing a raised floor. The cavity created by a raised
floor can hold moisture and allow mold to build up.
Operate a dehumidifier from spring to fall—especially important in
basements that have flooded in the past. Elevated humidity levels trigger
mold growth in areas that may not have been decontaminated. Keeping
moisture controlled is a preventive measure.
Lastly, remain alert for problems.
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ry to get a large unit that can work at lower indoor air temperatures.
When buying one, get a unit that is rated to be energy efficient.
You may need more than one unit to get things dry fast. Borrow
or rent additional dehumidifiers if you can.
Dehumidifiers are rated at a liquid removal rate, expressed as litres or
gallons a day.
A rate of 10 gallons a day is equivalent to 45 L a day. Generally, this rating
is for an indoor temperature of about 23°C (73ºF)—but it may differ for
different manufacturers.
It is very important to note that the dehumidification rate drops rapidly if
the indoor temperature is lower than the rating temperature, and, it climbs
even more rapidly at higher temperatures. If supplemental heat is not
provided, use a unit with an automatic defrost. Dehumidifiers that don’t
have an automatic defrost cycle will stop removing water altogether when
the air temperature drops below about 15°C (59ºF).
If your unit does not have a fan to circulate air, then provide one, so that
the air in the space is well mixed and the air moves fast enough over wet
surfaces to move moisture towards the dehumidifier.
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Few publications deal with the problems involved in cleaning up a house
after a flood. Repairing Your Flooded Home, an American Red Cross
booklet funded by the U.S. Federal Emergency Management Agency, is a
notable exception.
Single copies are available from:
FEMA Publications
P.O. Box 70274
It is also available from local chapters of the American Red Cross, as
publication ARC-4477. Both these sources are designed to serve Americans
but will supply single copies to Canadians.
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A handy pocket book recommended for every homeowner, especially those in
flood-prone areas. It's all here-information on managing plumbing breaks, sewer
backups and the aftermath of flooding. You'll learn what to do in each case with
topics including basic clean-ups, house decontamination and dealing with flooded
electrical equipment. Also includes helpful tips on handling the after-effects
of house fires.
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