Flooding and Well Water Safety
During a flood, there is an increased risk that drinking water wells may become contaminated
with bacteria and/or any other contaminants that may be present in the flood water. Any well
water system, whether deep or shallow, can become contaminated when flooding occurs.
Homeowners are responsible for assessing the risk to their wells and should boil water used for
drinking and cooking if the risk is high.
Once the flood waters recede, everyone with a private water supply that has been affected by
flooding should get a bacteria test done before resuming usual water consumption. Laboratory
contact information can be found under ‘Steps for testing well water’.
Risk factors for well water
There is an increased risk of contamination of well water when:
• wells or aquifers are shallow and/or the overlying soils are permeable (ex: sand or gravel)
• wells are located in pits or depressions where water can pool
• wells have rusted, cracked or unsealed casings that do not extend at least 30 centimeters
• wells are near septic tanks or fields, barns, feed lots or other potential sources of contamination
• wells are near unsealed abandoned wells, sink holes, quarries or other potential groundwater
• wells close to yours are flooded and may be contaminated
• wells are in close proximity to surface water sources, such as a stream, river or lake
When boiling is necessary
If any of the above risk factors pertain to your well and your property is experiencing flooding,
or if you notice a change in the colour, clarity, taste or odour of your well water; then tap water
used for drinking or for preparing food should be brought to a rolling boil for one minute.
Once boiled, the water is safe to be used for:
• making infant formula and juices
• making ice
• washing fruits and vegetables
• brushing teeth
An alternative to boiling water is to use water from a known safe source such as bottled water.
For additional information, please see Manitoba’s Boil Water Advisory Fact Sheet #1 ‘Boil
Water Advisory For Drinking Water Only’.
Using water for other domestic purposes
Tap water from flood-affected wells can be used for:
• washing dishes
Adults, teenagers and older children can use the water to shower but should avoid swallowing
the water. Toddlers and infants should be sponge bathed instead of bathing in a tub.
Testing well water
Once flood conditions have subsided, your well water should be tested by an accredited
laboratory for bacterial contamination. You should continue to boil your water or use bottled
water until testing confirms the water is safe for drinking or food preparation.
Homeowners are responsible for collecting their own well water samples. For instructions on
how to collect a proper water sample, please see Manitoba’s Well Water Fact Sheet #2 ‘How
to Test Well Water For Bacteria’.
Sample bottles, a sample submission form, and instructions for sampling are available from
most rural municipal offices, Manitoba Conservation and Water Stewardship offices, or
from the laboratory.
It is very important to follow the sampling instructions provided by the laboratory and ensure
that the sample submission form includes accurate contact information and well location
information (ex: legal land description).
Bacteria testing subsidy program
The Province of Manitoba offers private water system owners a once-a-year subsidy for
bacteriological (total coliform and E. coli) analysis of their drinking water through Horizon
Lab. If the first sample result indicates that bacteria are present in the water, homeowners will
receive a coupon from the lab for one resample free of charge.
The total price to homeowners for the once-a-year subsidized sample is $19.16 (tax included).
Horizon Laboratory Ltd.
4055 Portage Avenue Street
Winnipeg, MB R3K 2E8
Other accredited laboratories
Two other laboratories in Manitoba are accredited to do bacteriological testing of water and offer
this service to private well owners. The Province doesn’t subsidize testing at these laboratories
and private well owners are encouraged to contact the laboratory directly for pricing.
1329 Niakwa Rd East, Unit 12
Winnipeg, MB R2J 3T4
Toll Free: 1-800-607-7555
Unit D, 675 Berry Street
Winnipeg, MB R3H 1A7
Toll Free: 1-866-800-6208
Submitting well water samples
Sample bottles need to be dropped off at one of the above mentioned laboratories within
24 hours of collection. Water samples must remain sealed and kept cool. Samples that get
too warm, freeze, or sit too long will give incorrect results.
Receiving water samples results
Once testing is completed, the results for your well water sample will be forwarded to you
by the laboratory along with follow-up instructions if the well showed signs of contamination.
If you do not receive the results within two weeks of submission, you should follow up with
If there is an immediate concern about the safety of your water (total coliform >10 and/or E. coli
present), the laboratory, or a drinking water officer, will try to establish live voice communication with
you within a few days following sample submission to advise you of the concern.
Visit the Office of Drinking Water website at www.manitoba.ca/drinkingwater or call the Private Well,
Education and Outreach Coordinator at 204-948-1351 if you have questions about your results or on
Well restoration after flooding subsides
Extensive well restoration may be needed if your well has been structurally damaged, completely
submerged, overtopped, or if you’ve seen flood water draining into your well as opposed to
wells that may have had a little seepage.
Floodwater and sediment can damage pumps and their electrical components. All assessments,
repairs and replacements should be done by qualified professionals where this type of extensive
damage has occurred. It may not be safe to turn on your pump until your well is cleaned out,
and all sediment and floodwater are removed.
Well owners who have experienced this type of problem should contact the Groundwater
Management Section at 204-945-6959 or other appropriately qualified professionals (ex:
licensed well drillers or plumbers) in their local area.
For more information
For more information on drinking water safety, water treatment devices, help with interpreting
your drinking water quality results, or to receive a copy of other drinking water fact sheets,
please visit the Office of Drinking Water website at www.manitoba.ca/drinkingwater or contact
the Private Well, Education and Outreach Co-ordinator at 204-948-1351. To locate a local office
near you, please refer to the website at http://www.gov.mb.ca/conservation/waterstewardship/
For information on certification for water treatment devices, visit www.nsf.org.
For information on well driller reports, well construction, well sealing, or for a listing of licensed
well drillers, contact Manitoba Conservation and Water Stewardship, Groundwater Management
Section at 204-945-6959.
For health information, contact Health Links at 204-788-8200 in Winnipeg; toll free at
1‑888‑315-9257 or contact your local public health office. To find your nearest office, go to: