Water from a well that has been flooded should be assumed to be contaminated.
Do not use the well water for drinking, cooking, making ice, brushing
teeth, or even bathing until you are satisfied that the water is not contaminated.
Floodwater can be contaminated by substances from upstream, such as
sewage from flooded septic systems or wastewater treatment plants, manure,
pesticides or fertilizer applied to cropland that was flooded. A septic
system in the vicinity of a well also can cause contamination when the
soil is flooded. Wells that are inside pits may be flooded even if the
surface is not covered with water.
In order to ensure that the water is safe, the well should be disinfected,
then the water should be tested to make sure pathogens have been completely
Disinfecting a well
Well contractors or drillers may be contacted to disinfect the well,
or you can do it yourself in some cases. The Indiana Department of Environmental
Management has an illustrated guide
for disinfecting a well on the web.Be sure to follow the instructions
carefully, which include the following steps:
• Turn off electric power to the pump and remove the well cap.
• Prepare a bleach and water solution and pour the solution
into the top of the well. (instructions are in the IDEM
• Recirculate the water by connecting a hose to a faucet and
spraying the water back into the well for at least 15 minutes.
• Open every faucet in the system and let the water run until
the smell of chlorine can be detected, then close all the faucets
and seal the top of the well.
• Allow the chlorinated water to stand in the system for several
hours, preferably overnight.
• The following day, operate the pump by turning on all faucets,
continuing until there is no chlorine odor.
Testing well water
Before you resume using the well, collect a water sample and have it
tested by a certified laboratory. Call your county health department
to find a laboratory near you. Some local hospitals may also test water
samples for bacteria. Testing water for bacteria ranges from $8 up to
about $30 depending on the lab. For more information see our page dedicated
to water testing.
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 sources for these types of contaminants,
special treatment is required. Homeowners can call the EPA Well Care
Hotline at (888) 395-1033 if contamination by non-biological elements
Another impact that flooding can have on your well is the damage or
deconstruction of the well in general. Fast moving floodwater can carry
debris that could dislodge well construction materials or distort the
casing. The coarse sediment in floodwater also could erode pump components.
Inspect the well for physical damage or look for signs of leakage. In
the case of a damaged well, consult a licensed water well contractor
to find out if repairs are needed.
Additionally, flooding can damage your well pump and electrical systems.
If the pump and/or electrical system have been under water do
not turn on the pump because of the potential danger of electrical
shock or damage to your well or pump. Once floodwaters have receded
and the pump and electrical system have dried, have a qualified electrician
check the wiring system.
Obtaining clean water
Individuals with flooded wells are encouraged to find an alternative
source of water for drinking, cooking and washing. For example, you
may be able to get water from a neighbor's well if you know it is safe,
or from a public water supply. Purchasing bottled water also is a good
alternative. If you can't find a convenient source of safe water, boil
your well water for five minutes before use.
Homeowners returning to their home after a flood may be anxious to
use the water. But remember that flooding presents special health risks
and requires extra attention to protect your family's health.
Additional resources: Information about other drinking water topics is available through the EPA publication "Water
on Tap" or at the EPA Web page "Drinking
Water and Health: What You Need to Know" .