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Coping with floods, cleaning up afterwards –
and staying healthy
This leaflet has been put together to provide advice and background information on
staying free from infectious disease during and after flooding, including cleaning up
the home after the flooding has subsided. This briefing material has been produced
for healthcare professionals, the media and others who are looking for some
background understanding of hygiene issues related to flooding and/or are
responsible for providing guidance to the public on coping with hygiene issues
associated with flooding.
Background
Flooding is the most common type of natural disaster world-wide – and accounts for
40% of all natural disasters. Although for hundreds of millions of people living in
lowland river-line or coastal areas in South East Asia, flooding is a common
occurrence and an accepted part of life, in areas such as Europe and North America,
extensive flooding has, until recently, been considered a rare phenomenon. In the
last 5/6 years however, incidents of serious flooding in Europe and the US have
increased. In Prague, in 2002, more than 35,000 people were evacuated from their
homes when the Vltava River burst its banks. In 2003, there was significant flooding
in Florida and Jamaica following the hurricanes which hit the area, whilst the city of
New Orleans was very severely affected in 2005. In the UK five million people live in
places with a risk of flooding. In the last few years there have been serious incidents
of flooding in the Severn valley and also in Carlisle, whilst in 2007 we have seen two
serious incidents of flooding, firstly in Yorkshire and later again in the Severn valley,
but also in the Thames valley.
Flooding – what are the risks of infectious disease?
Although, for countries such as the UK, the risk of infections and illness after local
flooding is considered to be generally low, and in the past the number of reports of
illness, gastric or otherwise, after flooding has been minimal, the extent of recent
flooding problems such as those in the UK is unprecedented which means that it is
impossible for local authorities to give a true assessment of the extent of the
infectious disease risk. This means that we have to assume that the risks are finite
and take preventive measures to protect against infectious disease. Protecting family
members who are at increased risk of infection1 is particularly important. Once one
1
Up to 1 in 7 people in the UK community is considered at increased risk of infection. The largest proportion of these
people are the elderly who have generally reduced immunity to infection which is often exacerbated by other illnesses
like diabetes, malignant illnesses, etc. It also includes the very young, and patients discharged from hospital, taking
immuno-suppressive drugs or using invasive systems etc. All of these groups, together with family members who
carry HIV/AIDS, are increasingly cared for in the home.
member of the family becomes infected, the infection can spread very rapidly to other
family members and into the community.
Flood water affecting the home or other property (and the surrounding environment)
is quite likely to be contaminated with sewage and other organic material such as
animal faeces, rotting vegetation etc. from the environment and, therefore, it must be
assumed that it may be contaminated with human or animal pathogens (either
bacteria or viruses). A July 2007 study of flood water samples taken from swamped
streets in Tewksbury showed the presence of coliforms. Although it is likely that
pathogens entering floodwater from sewage or other sources will become much
diluted, there is a small risk that people may contract a stomach bug if they come into
direct (hand to mouth) contact with contaminated water or if they handle food with
contaminated hands.
It must also be borne in mind that floodwater and sewage when it subsides leaves a
muddy deposit, both indoors and in the immediate environs of the home. It may take
a long time to dry out after flooding, especially in humid climates, and moulds can
establish and grow on surfaces causing spoilage of items. Germs deposited on these
surfaces will gradually die out, but whereas some pathogens e.g. Campylobacter die
rapidly, others such as norovirus and C.difficile can persist and remain infectious for
days, weeks or even months. These organisms can be transferred from
contaminated surfaces via hands directly into the mouth or onto food, or indirectly via
hands into food. As it is not always clear whether flood water, environmental surfaces
and in some cases tap water, are contaminated with pathogens or not, the basic
advice is to assume, unless otherwise advised, that they are and take rigorous
hygiene precautions to prevent spread of infection in the home.
Basic Hygiene Precautions
Key hygiene precautions in the event of flooding are as follows and appropriate
hygiene measures are described in more detail below:
 Wherever possible, avoid coming into direct contact with floodwater.
 Do not let children play in floodwater and wash their hands frequently, particularly
before snacks and meals. Decontaminate floodwater-contaminated toys before
allowing them to be used again.
 If it is necessary to come into contact with floodwater, wear waterproof gloves
(such as household cleaning gloves) and wellington boots. Cuts and other open
wounds should be covered with a waterproof plaster.
 Wash hands thoroughly with hot water and soap, especially after contact with
floodwater or taking part in cleanup/decontamination activities - and ALWAYS
before handling or eating food, or feeding children.
 Ensure that items or surfaces which may have been in contact with flood water,
including food contact surfaces (countertops, chopping boards and cleaning
cloths, eating utensils (cutlery and crockery)) and hand contact surfaces (door
handles, tap handles, stair rails etc.) but also toys, clothes and soft furnishings,
are decontaminated before use.
 Food or drink suspected of being contaminated should be thrown away. Rigorous
standards of hygiene are important during handling and preparation of food.
 Drink only water which is “clean” This means drinking bottled water or water
which has been decontaminated by boiling of treatment with a disinfectant.
Where the drinking water supply is either interrupted or contaminated, it is
important to take precautions for formula-fed infants.
 Anyone who has accidentally swallowed or been in contact with contaminated
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water or sewerage who develops diarrhoea, fever or abdominal pain in the
following 10 days should seek medical advice from their GP or (for UK) from NHS
Direct on 0845 4647.
Read on for more detailed guidance. Please note that there is some repetition in the
following material, to ensure that, for people who may refer to only certain sections,
the information they obtain is comprehensive:
Hand Hygiene
The hands are “critical control points” for infection transmission in the home, since
they come into direct contact with known “portals of entry” for pathogens (mouth,
nose and conjunctiva of the eyes). For pathogens such as norovirus the “infectious
dose” (the number of virus particles needed to cause infection) can be very small (110 particles). Hands are thus a key last line of defence against the ingestion of
pathogens, which is why hand hygiene is so important. During flooding and during
the clean up operation hands can become contaminated by direct contact with flood
water. Hands can also become contaminated by contact with surfaces which have
been contaminated with flood water where some pathogens can survive on these
surfaces even after they have dried out.
Since handwashing is intended to prevent transfer of pathogens from floodwater
directly into the mouth, or onto food which is then eaten, key times for handwashing
are:
 After clean up activities associated with flooding.
 Before preparing and handling cooked/ready-to-eat food.
 Before eating food or feeding children.
Hand hygiene is also important:
 After contact with potentially contaminated surfaces.
How to wash hands:
Handwashing “technique” is very important. Rubbing with soap and water lifts the
germs off the hands, but rinsing under running water is also vital, because it is this
process which actually removes the germs from the hands. The accepted procedure
for handwashing is:
 Ensure a supply of liquid soap, warm running water, clean hand towel/disposable
paper towels and a foot-operated pedal bin.
 Always wash hands under warm running water.
 Apply soap.
 Rub hands together for 15–30 seconds, paying particular attention to fingertips,
thumbs and between the fingers.
 Rinse well and dry thoroughly.
In situations where soap and running water is not available an alcohol- based hand
rub or hand sanitiser should be used to achieve hand hygiene:
 Apply product to the palm of one hand.
 Rub hands together.
 Rub the product over all surfaces of hands and fingers until your hands are dry.
Note: the volume needed to reduce the number of germs on hands varies by product.
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During the flooding, things are likely to be very chaotic, and even very basic hygiene
measures such as handwashing may not be possible due to lack of clean water. In
this situation one very simple thing which people can do which can significantly
reduce the risk of disease is to avoid putting their fingers to their mouth.
General cleaning up inside your home
On returning home after a flood, it is important to be aware that flood water may
contain harmful organisms and that small numbers of these organisms will remain on
floors, walls and other surfaces after the floodwater subsides:
 Wear wellington boots and waterproof gloves and apron during cleanup. Cover
any open cuts with waterproof plasters.
 Keep children and pets out of the affected area until cleanup has been
completed.
 Remove as much silt and water as possible from the home. Where there are
floorboards the space under the ground floor may need pumping out. Good
ventilation and heating of the home will speed up the drying process and prevent
mould growth. Pathogenic bacteria, viruses and protozoa also die out more
rapidly on dry surfaces.
 Remove and discard all soft furnishings and fittings (wall coverings, rugs,
mattresses, carpeting, carpet underlay, upholstered furniture, cosmetics, stuffed
animals, baby toys, pillows, foam-rubber items, books, and paper products) that
are damaged beyond repair.
 As soon as possible, transfer all refuse to secure plastic bags or other containers
to prevent the spread of germs until refuse can be taken away
 All hard surfaces (walls, hard-surfaced floors, household surfaces and furniture)
should be hygienically cleaned (see below for directions for hygienic cleaning of
surfaces). Be particularly careful to disinfect surfaces that may come into contact
with food, (e.g. work surfaces, food storage shelves, refrigerator surfaces etc)
and surfaces which come into contact with the hands (e.g. door handles, tap
handles, toilet flush handles, and stair rails). Areas where small children play
should also be cleaned and disinfected. Allow all surfaces to dry thoroughly –
good ventilation and heating will speed up the drying process.
 For those items which are not irreparably damaged, but which cannot be washed
or dry cleaned such as mattresses or upholstered furniture, air dry them in the
sun and then if there is no risk of colour damage spray them thoroughly with a
solution of bleach.
 Steam clean carpeting if possible.
 For areas where mould has already begun to develop, a concentrated solution of
bleach (see hygienic cleaning of surfaces below) may be used to kill mould and
whiten and remove the black stains that the mould produces. When the surface is
visually clean, clean again with a fresh solution of bleach in order to kill any
remaining non-visible mould spores. Allow all surfaces to dry thoroughly.
In addition:
 Wash hands with soap and water after being in contact with floodwater or items
that have been contaminated. Always wash hands before eating or preparing
food.
 Wash all clothes worn during clean up activities in hot water and detergent. Wash
them separately from uncontaminated clothes and linens.
 Use fans, air conditioners, heaters and dehumidifiers, if available, to help the
drying process but bear in mind the advice below under ‘heating and ventilation’.
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Inaccessible areas such as under floorboards may smell but are not necessarily a
health hazard. Get further advice from the environmental health department if the
smell persists.
As property dries out, vacuum to remove loose material and dust on a regular
basis.
Soft furnishings, clothing, linens and bedding
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Bedding, clothing and other soft/fabric articles including children’s toys etc.
should be decontaminated as below.
Other soft furnishings that have been contaminated and cannot be put in a
washing machine will have to be professionally cleaned. If this is not possible,
they may have to be disposed of.
Wash all clothes worn during the cleanup in hot water and detergent. These
clothes should be washed separately from uncontaminated clothes and linens.
Hygienic cleaning of laundry
Laundry can be made hygienically clean by:
 washing at 40-60°C with a bleach-based product (check ingredients on the
package)
 washing at 60°C or above (using any product as the higher temperature kills
germs).
Washing at temperatures of 40°C or less with a non bleach product is considered to
carry a risk of inadequate decontamination.
Food preparation and storage
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Do not be tempted to salvage foodstuffs (including tins) as they may be
contaminated with sewage and chemicals left from the floodwater. Discard any
food which has been in contact with sewage or floodwater.
If it is not possible to reach shops, eat canned food provided that the can has not
been punctured, corroded or shows signs of leakage. Thoroughly clean and then
disinfect the lid of the can with a solution of bleach to prevent contaminants from
entering into the contents on opening. If the contents of the can have an
unpleasant odour or colour or if the food looks mushy and the liquid cloudy,
dispose of the can in a sealed plastic bag. NEVER taste the food from cans that
show any signs of spoilage in order to avoid the risk of botulism poisoning.
Frozen food that has been at room temperature for a few hours should be
discarded.
Put flood-damaged food in black plastic refuse sacks, seal and put out when your
next refuse collection is due.
Wash your hands before preparing food and before eating a meal or snack.
Ensure all surfaces that food will come into contact with are made “hygienically
clean” before use (see below for instructions on hygienic cleaning of surfaces). If
work tops and other areas show signs of damage, avoid food contact with these
areas. Ensure all surfaces where food will be stored are hygienically cleaned,
including shelves in the refrigerator.
All crockery, cutlery and cooking utensils (pots and pans) that come into contact
with food MUST be “hygienically cleaned” before re-use. If an adequate supply of
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hot water is available this can be done by detergent-based cleaning followed by
thorough rinsing. If available as dishwasher can be used.
Do not use untreated floodwater for food preparation. Advice on treatment of
water is given below. Use boiled water which has then been allowed to cool to
wash food which is eaten raw. It is safe to use unboiled tap water for cooking of
food if it will be boiled during the cooking process.
Water
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Follow the advice of the local water company regarding the safety of the water
supply. If a water treatment works becomes flooded, alternative supplies are
normally available but consumers may be advised to boil water before drinking or
temporarily refrain from using water for domestic purposes.
Contact the local water company if there is a noticeable change in water quality,
such as discolouration or a change in taste or smell. If in doubt, boil all water
intended for drinking or use bottled water.
Ensure water taps are cleaned and disinfected and run water through them
thoroughly before using them for the first time.
If water is a private supply rather than mains, it is very important to check that it
has not been affected by flood water. If the supply has been covered with flood
water or changes colour or taste, boil or otherwise treat the water before drinking.
If drinking water becomes contaminated
Boil water, including all water for drinking, brushing teeth, washing food and making
ice. If a source of power is not available, then water can be treated with chlorine or
iodine. If the water is turbid it must be pre-treated before boiling or disinfection. Use a
bleach solution to rinse water storage containers before reusing them after flooding.
Continue to treat water until the supply has been tested and shown to be safe.
Boiling water
Bringing water to a rolling boil will kill pathogens effectively. A rolling boil is when the
water is bubbling so hard that the bubbles keep coming up when the water is stirred.
A holding period of 3-5 mins will ensure that water is safe, except in situations where
contamination with spore-forming bacteria, fungal or protozoal cysts or hepatitis virus
is suspected, in which case 10 mins is advised. Water from the hot tap is not suitable
for drinking.
Chemical disinfection of drinking water
Where chlorine or iodine tablets are available, they should be used as directed by the
manufacturer. Alternatively water should be disinfected with hypochlorite in the form
of bleaching powder or hypochlorite solution for 30 mins. The final concentration of
chlorine should be 0.5-1mgm/l available chlorine after 30 mins. The amount of
chlorine needed depends mainly on the concentration of organic matter in the water
and should ideally be determined for each situation using a test kit. If this is not
available, a slight smell of chlorine is a crude indicator.
For details on preparing chlorine solutions consult the following: Household Water
Treatment and Safe Storage Following Emergencies and Disasters.
http://www.who.int/household_water/resources/emergencies.pdf
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For disinfection with iodine a concentration of 3.7 mg/l, contact time 10 mins, is
required (6.3 mg/l if virucidal contamination is suspected).
Pre-treatment of turbid water
Turbid water should be filtered through a cotton cloth to remove any solid materials,
 treated with alum and bleaching powder, stored for at least 2h and then decanted
or filtered through a clean cloth. For pre-treatment add 10g alum and 5g lime per
100l of turbid water.
For further advice on treatment of water consult:
Emergency treatment of drinking water at point-of-use. WHO technical note for
emergencies No. 5
http://www.who.int/water_sanitation_health/hygiene/envsan/tn05/en/index.html
.
Water for infants
Where the drinking water supply is either interrupted or contaminated, it is important
to take precautions for formula-fed infants. In these circumstances there are three
options for the use of water to make infant formula milk:
 For preference, use bowser or bottled water which has been boiled and allowed
to cool. Then follow the manufacturer's instructions on making up the feed.
 Commercially ready made formula milk may be used as an alternative to
powdered feeds made up with bowser water.
 If neither option 1 or 2 are possible because there is no energy to allow boiling,
bottled water (table, spring or mineral water) can be used unboiled to prepare
baby feeds, but the prepared feed should then be used immediately. Unboiled
bowser water should not be used.
Children
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Keep children and pets out of affected areas until clean-up has been completed.
Wash children’s hands frequently – and always before meals.
Wash flood water-contaminated toys with hot water and detergent. Some toys
can be cleaned by being put inside pillow cases and into ordinary clothes
washing machines.
Gardens and play areas
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Do not let children or pets play on grassed or paved areas which have been
flooded until the area has been cleaned.
Remove any toilet waste from affected areas and bury
On patio and other surfaces, the risk of spread of germs from residues of faecal
material can be reduced by application of concentrated bleach solution*. Sunlight
and soil will help destroy harmful bacteria and outdoor areas will be safe to use
within a week or so after flooding.
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Other health concerns
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Be aware of potential chemical hazards during flooding. Avoid contact with water
and materials which may have been chemically contaminated.
 If the floodwater contained oil, petrol or diesel it should go away with the
floodwater and silt. Any remaining oil, diesel or petrol contamination can be
removed using a detergent solution and washing the surface down after initial
cleaning has been carried out.
 Remember that petrol or diesel generators, dehumidifiers and pressure washers
should never be used indoors without adequate ventilation. The exhaust gases
contain carbon monoxide which can quickly build up to poisonous levels without
proper ventilation.
 Electrical appliances, which have been in contact with floodwater, should not be
switched on until a competent electrician has checked them.
Further advice on these issues is available on the UK Health Protection Agency
website (http://www.hpa.org.uk/flooding) or contact NHS Direct on 0845 4647 or visit
their website http://www.nhsdirect.nhs.uk.
Hygienic cleaning of surfaces
Since flood water affecting the home or other property is quite likely to be
contaminated with sewage, animal faeces, refuse etc., it is important that all surfaces
are “hygienically cleaned” in order to get rid of germs (pathogenic bacteria, viruses
and protozoa) as well as visible dirt. Hygienic cleaning of surfaces can be achieved in
a number of ways according to the extent of the contamination and the facilities
available:
 Hygiene cleaning using detergent (liquid or soap) and hot water. Detergent
(laundry or dish detergent) or soap and hot water cleaning can be used to
produce a hygienically clean surface provided that the surface is thoroughly
rinsed using clean running water. Mechanical action using a cloth, sponge or
brush to maximise removal of soil and microbes is an important part of the
process. Removal of soil by wiping with a cloth without subsequent rinsing is not
considered sufficient to achieve a surface that is hygienic. Use of a contaminated
cloth can actually spread pathogenic organisms onto previously uncontaminated
hands and hand and food contact surfaces.
 Hygienic cleaning using soap or detergent and a disinfectant product. This
process should be used on large surfaces which cannot be rinsed or for situations
where an adequate supply of running water is not available:
o Surfaces should first be cleaned to remove the visible soil using a solution of
detergent or soap. Using a clean cloth apply to the surface. Since
disinfectants are inactivated to a greater or lesser extent by the presence of
soil, soiled surfaces, particularly heavily soiled surfaces MUST be cleaned
before application of a disinfectant.
o If the surface is only “superficially” dirty, it may be hygienically cleaned using
a combined disinfectant/cleaner. The solution should be applied with a clean
cloth or via a spray bottle and the surface then wiped. If necessary repeat
the process until the surface appears visibly clean.
o Use a disinfectant or disinfectant/cleaners such as a bleach-based product*,
which is active against all types of pathogens including bacteria, bacterial
spores, viruses and protozoa. Consult the manufacturers instructions for
information on the “spectrum of action”, and method of use (dilution, contact
time etc).
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* Use a solution of bleach, diluted to 0.5% or 5000ppm available chlorine. Household
bleach (both thick and thin bleach) typically contains 4.5 to 5.0% (45,000-50,000
ppm) available chlorine. In situations where concentrated bleach is required a
solution containing not less than 4.5% available chlorine should be used.
Bleach/cleaner formulations (e.g. sprays) are formulated to be used “neat” (i.e.
without dilution). It is always advisable however to check the label as concentrations
and directions for use can vary from one formulation to another.
For more details on choosing the appropriate disinfectant, consult the IFH information
sheet “Cleaning and disinfection: Chemical Disinfectants Explained”
Other sources of Information.
Further general advice in relation to flooding is available on the Health Protection
Agency’s website at http://www.hpa.org.uk/flooding.
 Flooding
–
advice
for
the
public.
http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/1317140405287
or contact NHS Direct on 0845 4647 or visit their website http://www.nhsdirect.nhs.uk
 Flood health advice http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=22
84.
Advice for clean-up after hurricanes and floods from Center for Disease Control and
Prevention (CDC), Atlanta, USA. http://www.bt.cdc.gov/disasters/floods/
IFH guidelines and training resources on home hygiene:

Guidelines for prevention of infection and cross infection the domestic
environment. International Scientific Forum on Home Hygiene. Available from:
http://www.ifh-homehygiene.com/best-practice-care-guideline/guidelinesprevention-infection-and-cross-infection-domestic
 Recommendations for suitable procedure for use in the domestic environment
(2001). International Scientific Forum on Home Hygiene. http://www.ifhhomehygiene.org/best-practice-care-guideline/recommendations-suitableprocedure-use-domestic-environment-2001
 Home hygiene - prevention of infection at home: a training resource for carers
and their trainers. (2003) International Scientific Forum on Home Hygiene.
Available from: http://www.ifh-homehygiene.com/best-practice-training/homehygiene-%E2%80%93-prevention-infection-home-training-resource-carersand-their
These give comprehensive guidelines on how, when and where, hygiene should be
applied in the home to prevent the spread of infectious disease.
This resource was last updated February 2014
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