WITH INFECTION RISKS
THE HOME AFTER A FLOOD
Advice Sheet issued by the International Scientific Forum on Home Hygiene
This resource has been put together to provide advice and background
information on cleaning up the home and post-flood decontamination of
drinking water sources after floods. It also gives advice on treatment
of water for domestic use during the flood.
1. A global problem
Flooding is the most common type of natural disaster worldwide – 40% of all
Whilst the numbers of other types of natural disasters continue to decrease,
the number of floods continues to rise.
year in South East Asia, hundreds of millions of people living in lowland
river-line or coastal areas are affected by flooding. In the
five million people live in places with a risk of flooding.
apart from the devastation caused by the Tsunami in
South East Asia,
many countries around the world are often devastated by floods, particularly
during the monsoon time:
In South East Asian
India, Bangladesh, Myanmar, Nepal, Laos, Vietnam etc monsoon floods &
cyclones are almost annual phenomena
The 1999 cyclone in Orissa
killed 10,000 people and affected 10-15 million people.
Bangladesh the devastating flood of 1991 & 1998 affected more than 30
million people, and the death toll was 140,000
The recent floods in
China & Korea have made more than 2 million homeless
Torrential rain and
flooding hit the
and Haiti with drastic effects
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
and Jamaica following the hurricanes which hit the area.
2. Health risks after a flood
Floods present obvious
health risks including drowning, electrical shock and starvation. Advice
and fact sheets on what to do before a flood, once the flood arrives and
after a flood can be found on the FEMA website.
Floods can also bring the
risk of epidemic disease, which if not addressed appropriately can persist
in the environment a long time after the flooding has ceased. This is
exacerbated in hot climates. In the rural areas such as those in South
East Asian countries like Myanmar, Nepal, India, Bangladesh, Laos, Vietnam
etc many or most of the tube wells/Dug wells which serve as sources for
domestic water supply (both for private as also for public supply) get
grossly contaminated with faecal matters during the floods. Unless they
are thoroughly decontaminated (super chlorination) during the post flood
situation, water borne infections like diarrhoea, dysentery, typhoid,
infectious hepatitis etc are likely to occur.
General guidelines for cleaning up and decontaminating water sources after a
water affecting the home or other property is likely to be heavily
contaminated with sewage and other organic material such as animal carcasses
and therefore, it must be assumed that it is contaminated with human
pathogens (germs). 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. Thorough cleaning and disinfection is
recommended on all surfaces affected. Ventilation is also important in order
to assist the drying process.
Protect yourself from
floodwater and other possible sources of germs as much as possible,
particularly covering open cuts and wounds on exposed skin.
Waterproof dressings, rubber gloves and a mask to cover the nose and
mouth are ideal if available.
It is advisable to wear rubber boots in case there has been a backflow
of sewage into the house.
As soon as possible,
remove and bury any faecal material from humans or animals to prevent
spread of germs. The risk of spread of germs from residues of faecal
material can be reduced by application of concentrated bleach solution*.
This can also help reduce the infection risk to those involved in
cleaning up the area.
As soon as possible,
transfer all refuse to secure plastic bags or other containers to prevent
the spread of germs until the refuse can be taken away.
Remove as much silt and
water as possible from the home. Good ventilation and heating of the home
will speed up the drying process, prevent mould growth and reduce the risk
of spread of germs.
Remove and discard
contaminated household materials such as soft furnishings and fittings
that are damaged beyond repair eg. wall coverings, rugs.
For those items which are
not irreparably damaged, but which cannot be washed or drycleaned 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
Steam clean all carpeting
Bedding, clothing and other
soft / fabric articles including children’s toys etc should be laundered
washing at 40-60°C with a bleach-based product (check ingredients on the
package), or washing at 60°C or above (using any product as the higher
temperature kills germs).
All hard surfaces should be
hygienically cleaned either by cleaning followed by disinfection or by
using a cleaner/disinfectant**.
Be particularly careful to thoroughly disinfect surfaces that may come
into contact with food, such as work surfaces, pantry shelves,
Areas where small children play should also be carefully cleaned and
disinfected with bleach. Allow all surfaces to dry thoroughly – good
ventilation and heating will speed up the drying process.
For areas where mould has
already begun to develop, a concentrated solution of bleach* may be used
to kill the mould and whiten and remove the black stains that the mould
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.
Any item that comes into contact with food such as crockery, cutlery,
utensils and cooking equipment MUST be “hygienically cleaned”** before
If an adequate supply of hot water is available this can be done by
detergent-based cleaning followed by thorough rinsing. Otherwise the
items should be cleaned and then disinfected by soaking in a solution of
Do not be tempted to
salvage foodstuffs. Any food item that has been in contact with floodwater
should be regarded as contaminated and discarded. If it is not possible to
reach shops, eat canned food provided that the can has not been punctured,
corroded or damaged in any way and is not showing any signs of bulging or
It is recommended to thoroughly clean and then disinfect the lid of the
can with a solution of bleach to prevent any 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
NEVER even taste the food from cans that show any signs of spoilage in
order to avoid the risk of botulism poisoning.
Never use untreated
floodwater for drinking, food preparation and cooking. Point of use
treatment of the turbid floodwater to make it drinkable can be undertaken
with a simple technique of coagulation, flocculation & disinfection.
Before treatment, remove any solid materials and filter through a cotton
As a rough guideline, it is suggested that 100 litres of turbid
floodwater can be initially treated with alum & lime and then after
settlement, the same should be disinfected with hypochlorite in the form
of bleaching powder (calcium hypochlorite) or hypochlorite solution. It
is suggested that 100 litres of turbid floodwater can be initially
treated with 10g of alum & 5g of lime. After settlement, the same should
be disinfected with hypochlorite in the form of bleaching powder or
hypochlorite solution for 30 minutes. The final concentration of
chlorine in the water should be 0.5 to 1 mgm/l available chlorine after
30 minutes, which can be determined using a test kit. If this is not
available, a slight smell of chlorine is a crude indicator.
Water sources must be
thoroughly decontaminated to avoid the risk of water borne infections with
Super Chlorination. This can be achieved by adding chlorine to the water
(in the form of bleaching powder (calcium hypochlorite) or bleach
solution) and ensuring a contact period of 24 hours. The final
concentration of chlorine in the water should be 25- 50mgm/l available
4. Useful sources of information.
a) On the IFH website
For comprehensive guidelines on how, when and where, hygiene should be
applied in the home to prevent the spread of infectious disease:
Guidelines for prevention
of infection and cross-infection in the domestic environment: Focus on
home hygiene issues in developing countries:
selection of suitable hygiene procedures for use in the domestic
b) On the Internet
Bleach contains hypochlorite. It is highly effective against viruses,
bacteria, yeast and moulds. Bleach acts very quickly (within 1 minute) but
longer times are required for killing moulds and fungi. Bleach is an
excellent “cleaner” for even the toughest soils, and for the removal of
mould growth. Bear in mind that chlorine-based bleaches can damage and/or
bleach fabrics, carpets, soft furnishings and can corrode metal surfaces.
Household bleach (both thick and thin bleach) for domestic use typically
contains 4.5 to 5.0% available chlorine. 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.
situations where concentrated bleach is required, a solution containing not
less than 4.5% or
45,000ppm available chlorine should be used.
**Hygienic cleaning of surfaces
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 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
Cleaning using detergent
(liquid or soap) and hot water. Detergent and hot water cleaning can be used
to produce a hygienically clean surface provided that the surface is then
thoroughly rinsed using clean (potable) 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.
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
If the surface is heavily
soiled, clean thoroughly to remove the visible soil using a solution of
detergent or soap. Using a clean cloth, apply a solution of bleach
diluted to 0.5% or 5000ppm available chlorine to the surface. Since
disinfectants are inactivated to a greater or lesser extent by the
presence of soil, heavily soiled surfaces MUST be cleaned before
application of a disinfectant.
If the surface is only
“superficially” dirty, it may be hygienically cleaned using a combined
bleach/cleaner containing 0.5% or 5000ppm available chlorine. 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.
Hygienic cleaning of laundry
Washing at temperatures of 40°C or less with a non bleach product is
considered to carry a risk of inadequate decontamination. Laundry can be
made hygienically clean by;
washing at 40-60°C with a bleach-based product (check ingredients on the
washing at 60°C or above (using any product as the higher temperature kills