What to Do After the Flood
Drilled, driven or bored wells are best disinfected by
a well or pump contractor, because it is difficult for the private owner
to thoroughly disinfect these wells. If you suspect that your well may
be contaminated, contact your local or state health department or agriculture
extension agent for specific advice on disinfecting your well. The suggestions
below are intended to supplement flood precautions issued by State and
local health authorities.
Well and Pump Inspection
- Flood Conditions at the Well - Swiftly moving flood water can carry
large debris that could loosen well hardware, dislodge well construction
materials or distort casing. Coarse sediment in the flood waters could
erode pump components. If the well is not tightly capped, sediment and
flood water could enter the well and contaminate it. Wells that are
more than 10 years old or less than 50 feet deep are likely to be contaminated,
even if there is no apparent damage. Floods may cause some wells to
- Electrical System - After flood waters have receded and the pump and
electrical system have dried, do not turn on the equipment until the
wiring system has been checked by a qualified electrician, well contractor,
or pump contractor. If the pump's control box was submerged during the
flood all electrical components must be dry before electrical service
can be restored. Get assistance in turning the pump on from a well or
- Pump Operation - All pumps and their electrical components can be
damaged by sediment and flood water. The pump including the valves and
gears will need to be cleaned of silt and sand. If pumps are not cleaned
and properly lubricated they can burn out. Get assistance from a well
or pump contractor who will be able to clean, repair or maintain different
types of pumps.
Emergency Disinfection of Wells that have been Flooded
Before Disinfection: Check the condition of your well. Make sure there
is no exposed or damaged wiring. If you notice any damage, call a professional
before the disinfection process.
- One gallon of non-scented household liquid bleach;
- rubber gloves;
- eye protection;
- old clothes; and
- a funnel.
If your water is muddy or cloudy, run the water from an outside spigot with a
hose attached until the water becomes clear and free of sediments.
Determine what type of well you have and how to pour the bleach
into the well. Some wells have a sanitary seal with either an
air vent or a plug that can be removed (a). If it is a bored
or dug well, the entire cover can be lifted off to provide a
space for pouring the bleach into the well (b).
Take the gallon of bleach and funnel
(if needed) and carefully pour the bleach down into the well
After the bleach has been added, run water from an outside
hose into the well casing until you smell chlorine coming from
the hose. Then turn off the outside hose.
Turn on all cold water faucets, inside and
outside of house, until the chlorine odor is detected in each
faucet, then shut them all off. If you have a water treatment
system, switch it to bypass before turning on the indoor faucets.
Wait 6 to 24 hours before turning
the faucets back on. It is important not to drink, cook, bathe
or wash with this water during the time period --- it contains
high amounts of chlorine.
Once the waiting period is up, turn on an outside spigot
with hose attached and run the water into a safe area where
it will not disturb plants, lakes, streams or septic tanks.
Run the water until there is no longer a chlorine odor. Turn
the water off.
The system should now be disinfected, and you
can now use the water.
Have your water tested for bacteria 7 to 10
days after disinfection.
| CAUTION: Because of the extensive flood area and the speed
and direction of ground water flow, your well may not be a safe source
of water for many months after the flood. The well can become contaminated
with bacteria or other contaminants. Waste water from malfunctioning
septic tanks or chemicals seeping into the ground can contaminate
the ground water even after the water was tested and found to be safe.
It will be necessary to take long range precautions, including repeated
testing, to protect the safety of drinking water.
Sampling and Testing the Well Water
Contact the local health department to have well water sampled and tested
for contamination. Or, call your state laboratory
certification officer to find a certified lab near you. You can get
this number from the Safe Drinking Water Hotline (800/426-4791).
If the health department issues sterile bottles for the private well
owner to collect water samples, follow all instructions for the use of
After the pump is back in operation, the health department should sample
and test the water at regular intervals.
| CONCERNS AND ADVISORIES
- If in doubt about the well water supply, follow health department
drinking and bathing advisories
- Remember that there is a danger of electrical shock from any
electrical device that has been flooded; consult a certified electrician.
Rubber boots and gloves are not adequate protection from electric
- Well disinfection will not provide protection from pesticides,
heavy metals and other types of non-biological contamination.
If such contamination is suspected, due to the nearness of these
contaminant sources, special treatment is required. Information
on home water treatment units (also called point-of-use and point-of-entry
units) is available from U.S. EPA by phoning the Safe
Drinking Water Hotline (1-800-426-4791). If you observe
chemical containers (including barrels and drums) that have moved
to your property, call your state or county health department
or the Superfund Hotline (1-800-424-9346).
- For information on long-term water quality conditions in the
area, consult the state or county health department. Well owners
may have information about the construction, or testing of their
well and this information will be helpful to the health department
in determining water quality conditions.
- Septic systems should not be used immediately after floods.
Drain fields will not work until underground water has receded.
Septic lines may have broken during the flood.