Residential Flooding

There are several ways floodwater can enter your home and pose health or safety risks. The following information on flood prevention, staying safe during a flood, and recovery after a flood will be useful to Ottawa residents in the event water enters homes from a leaky roof or basement, overland flooding such as a river overflow during the spring freshet, or from a leak from a pipe within your building. Being prepared and having a plan will help residents deal with the stress and disruption that go along with flooding events.

 Flooding prevention - Plan, Prepare, Be Aware

Prevent flooding

Floods can pose different levels of risk depending on the source of the water, the volume of water and how quickly and easily the floodwater can be removed. The City of Ottawa has useful information on their Flood Information website on the following topics:

Be prepared for an emergency

It is important to be prepared for emergencies. To be ready, have a kit with supplies that make you and your family self-sufficient in your home for 72 hours. The City of Ottawa has a Safety and Emergency Preparedness website with information on:

  • How to make your own emergency preparedness kit so you can be self-sufficient for at least 72 hours.
  • A special needs checklist to help ensure everyone's unique needs are provided for during an emergency.

The City and Conservation Authorities work to reduce flood risk

The City and Conservation Authorities take preventive steps to protect homes from the spring snowmelt or freshet.  This includes blasting ice on some sections of the Rideau River that are at risk of overland flooding before the freshet, clearing storm water drains, and providing an interactive map of areas at risk of overland flooding to residents.

Safe drinking water - Private well owners 

Well water can contain harmful bacteria that causes stomach cramps, diarrhea and other health concerns. Private well owners are encouraged to get their water tested every spring, summer and fall, even if it looks, tastes and smells fine. 

Whether your test results are positive or negative, understand that the sample you collected is just a "snapshot" of your well's water quality. The more samples you have tested, the more confident you can be about the quality of the water you are drinking.

In addition to regularly testing well water, owners should inspect their well at least once a year to make sure it is free from damage and in good working condition.

Learn more about free private well water testing.

 During a flood - Keep you and your family safe

There are several ways floodwater can enter your home and pose health or safety risks. The following information on staying safe during a flood will be useful to Ottawa residents in the event unwanted water enters your home.  Protecting yourself during a flood and restoring your home after a flood can be a very stressful time. Ottawa Public Health suggests the following information to help you protect yourself and your family from illnesses associated with contaminated floodwaters.

Stay safe

During the spring thaw, rivers, streams and lakes swell with snowmelt and rainwater, making them very dangerous for people and pets.  There is an increased risk of drowning and injury because of high water level, faster flow, cold temperature and debris in and below the water surface.

  • Do not wait to evacuate. Move to higher ground as soon as you can.
  • Stay away from edges of waterways, as the banks can be slippery.
  • Do not walk or drive through floodwater even if it looks like it is shallow. 
  • Keep children away from floodwater. 
  • Stay within sight and arm’s reach of children when outdoors near water
  • Keep pets on a leash. Do not try to rescue pets who are in cold water. 

Be aware that there are many risks in and around flooded areas and that you will need to take precautions in order to protect your health.

Prevent Infections and Illnesses 

Harmful bacteria, viruses, moulds and chemicals may be present in floodwater, even if they do not involve sewage backups. Always consider floodwater and surfaces that have been in contact with floodwater to be contaminated (not clean).  Wear personal protective clothing and equipment when you encounter floodwater.  This may include rubber boots, waterproof gloves, a facemask and eye protection (safety goggles).

  • If you cut or puncture your skin, clean and disinfect the wound as soon as possible and then protect it by keeping it dry and clean. Seek medical attention if you have not had a tetanus shot in the past 10 years or if signs or symptoms of infection, such as redness, swelling or oozing develop.
  • If you rely on a private well for drinking water, do not drink the water until you have determined if your well has been affected by floodwater and you have tested it for bacteriological safety. Use boiled or bottled water. Testing your well water should occur after the floodwaters have receded. 
  • Toilets and septic systems are often impacted by floodwater. Only flush your toilets and drain water from your sinks if your septic system is not submerged in floodwater in order to prevent sewage backing up into your home. 
  • Always wash your hands with soap and clean water or use an alcohol-based hand rub before preparing or eating food, after toilet use, after contact with floodwater, and after handling articles contaminated with floodwater. For more information on handwashing visit Ottawa Public Health Handwashing web page.
Safe drinking water - private well owners
If flood waters have reached the level of your well head, or covered your well head, your well water may be contaminated and not safe to drink.

Residents who own private wells affected by flooding are advised to:

  • Stop using your well water, use boiled, treated or bottled water for ALL water use, including drinking, preparing food, cleaning, bathing, hand washing.
  • If you want to continue to use your well water, bring it to a rolling boil for at least one minute and let it cool before using it for drinking, making infant formula, juices, ice or recipes, brushing your teeth, rinsing contact lenses, and washing food or dishes. Refrigerate your boiled water until it is used. 
Safe food donations
Food donations can be helpful to those impacted by a flood. Food donations are very much appreciated and should be taken directly to emergency shelters. Visit Ottawa Public Health's Food Safety web page for guidelines on how to donate food safely.

Prevent Injury and Loss of Life

Be aware of the following physical hazards during and after a flood:


Standing and flowing waters present drowning risks associated with driving, walking or swimming through floodwater. During overland flooding, such as a river overflowing, it is important to leave a flood risk area before waters rise to prevent being trapped and risking drowning.  If flooding is related to a rainfall event or plumbing issue, ensure people entering the area take precautions against drowning risks such as never enter a flooded area alone and wear a floatation device.


Electrocution is a safety risk when entering flood-damaged areas. Do not enter your basement, or other impacted areas of your home, if you know or suspect water has risen above the level of electrical outlets, baseboard heaters, and furnace, or is near your electrical panel. If you are unsure, have a licensed electrician check it out before you enter any areas with pooled water. Do not turn on any electrical appliance (major or small, furnace, water heater, etc.) if it has gotten wet. Have it checked by a qualified service technician to confirm it is safe to do so. 

Power outages and risk of carbon monoxide poisoning 

Do not use the following  indoors or in garages during a power outage:

  • charcoal or gas barbecues,
  • camping heating equipment
  • home generators
  • gasoline/diesel equipment (pumps, fans)

The use of these alternative sources can cause carbon monoxide (CO) to build up in your home. Make sure there is at least one working carbon monoxide detector installed at or near floor level.

Safety for children and people with disabilities

Ensure children are adequately supervised and keep them away from floodwater. Ensure people with disabilities are aware of the risks of floodwater and they have assistance getting to a safe and supervised place.  When outdoors, always keep children within arm’s reach in and around water.

Slippery surfaces, poor lighting, heavy objects and exhaustion

Surfaces will be slippery and falls with injuries are likely.  Poor lighting may increase risks of injury, especially if there are power outages or it is unsafe to turn on lights.   Working when overtired can result in injuries. It is important to set a realistic schedule and take frequent rest and nutrition breaks.  Objects are heavier when wet. 


Being exposed to cold water can increase the risk of hypothermia.  Wear waterproof outerwear, a warm layer of clothing and an inner layer of clothing that wicks moisture away from your body.  Be aware of the early signs of hypothermia (drowsiness, weakness and loss of coordination, confusion, shivering, and pale and cold skin).  


After a flood - Recovery tips

It can be a difficult task to clean up after a prolonged flood. The process can take a long time and involves considerable resources. The length of time to dry out affected areas will vary based on the materials that were impacted by the flood waters. Some materials absorb water more readily than others (e.g., concrete blocks versus poured concrete) and may take longer to dry. Some building materials, for example dry wall and insulation, must always be removed and discarded after contact with water. In general, cleaning and drying materials as soon as possible is the best way to prevent the growth of mould.

Cleaning up your home
Once it is safe to return to your home, be sure to take precautions to protect you and your families’ health and safety.
  • Ensure that a licensed electrician has determined that it is safe to turn on your power.  Wear rubber boots as a precaution to reduce the risk of electrocution.  Use caution when entering your home as appliances, heating, sewage systems and electrical components pose a risk of shock or fire;
  • Ensure that the building is structurally safe – watch for glass, holes or buckled walls and floors;
  • Use pumps and pails to remove excess water from your home;
  • Wear protective clothing such as rubber boots, coveralls, rubber gloves and eye protection when cleaning floodwaters and using cleaning products. An N95 mask should also be worn to protect against mould and dust.  
  • Use fans, dehumidifiers and open your windows to eliminate moisture in your home.  If you can clean and dry building materials within 48 hours, it is unlikely mould will develop;  
  • The Canadian Mortgage and Housing Corporation recommends preventing mould growth by disposing household items that cannot be dried within 48 hrs.
  • Be on the lookout for mould which can lead to health implications. Remove mould and mildew by washing surfaces with soap and water and follow up with a disinfectant such as diluted bleach.  Drying is critical to keeping mould from growing. 
  • Throw out food containers that cannot be properly cleaned, such as those with screw tops or corks.

Professional cleaning services are also an option and may be advisable in some situations. If you are doing it yourself, it is very important to ensure that the spaces are completely dry in order to control mould. Mould spores are all around us, waiting to grow and spread into mould when given moisture. Keeping things dry and the humidity low is the best way to control mould growth.

STEP 1: Gather the necessary cleaning supplies

Here are some of the items you may need for the clean-up:

  • Brooms
  • Mops
  • Buckets
  • Hose
  • Rags
  • Trash bags
  • Floor brushes
  • Sponge
  • Cleaning detergents/soap
  • Disinfectants
  • Goggles
  • Rubber boots
  • Rubber gloves
  • Face mask (N95 preferable)
  • Coveralls

STEP 2: What to wear when cleaning

  • Wear coveralls, rubber boots, gloves, face mask and eye protection. Also, an N95 mask should be worn to protect against mould and increased dust due to clean up efforts.
  • Always wash your hands with soap and clean water before preparing or eating food, after toilet use, after participating in flood clean-up activities, and after handling articles contaminated with flood water.

STEP 3: Sort damaged items to be repaired or discarded

It can be difficult to throw away items in a home, particularly those with sentimental value. However, keeping certain water soaked items may be unhealthy. Although it may not initially be visible, mould can start growing on anything that has been damp or wet for two or more days.

In general, belongings and household contents, such as upholstered furniture, that are wet and cannot be thoroughly cleaned and dried within 24-48 hours should be discarded, as they can remain a source of mould and bacterial growth. Please note again that building materials such as dry wall and insulation that are wet cannot be salvaged and must be removed and discarded.

Items that are usually discarded because they cannot be properly cleaned may include:

  • Bedding
  • Clothing
  • Books
  • Rugs
  • Carpets
  • Carpet padding
  • Leather furniture
  • Particle board furniture

Some of the above-mentioned items may be salvageable, however, the process may require expert assistance.

Always discard food that has been exposed to flood water. Discard food and beverage containers with screw-caps, snap lids, crimped caps (soda bottles), twist caps, flip tops, corks, and home canned foods if they have come in contact with flood water. These containers cannot be disinfected. The only safe flood-exposed foods are those sealed in metal cans and that have not been damaged. Thoroughly clean and disinfect with bleach and water all undamaged cans before opening.

Always throw away these flood-exposed items:

  • Cardboard
  • Cosmetics
  • Leather goods
  • Mattresses
  • Pillows
  • Medicines
  • Medical supplies
  • Stuffed animals
  • Soft toys
  • Insulation
  • Household hazardous materials (e.g., paints)
  • Household chemicals
  • Upholstered furniture

Please note that some of these items are considered hazardous waste and need to be disposed of properly. Visit or call 3-1-1 to see where to dispose of hazardous waste. Flood impacted areas may have special pickup instructions.

STEP 4: Clean up one room at a time

To clean flood contaminated areas that have non-porous surfaces and can easily be cleaned:

  • Drain all water
  • Remove visible debris
  • Clean with soap and water (using mops, cloths, sponge, brushes, etc.)
  • Rinse with clean water (e.g., damp mop)
  • Disinfect with a diluted household bleach in water. Bleach straight from the bottle is hazardous and must always be      diluted with water. Protect your skin and eyes when mixing.  15ml (1 tablespoon) of bleach added to 1 litre of water is adequate to disinfect hard surfaces.

STEP 5: Dry out your home and remove mildew by lowering the humidity

It may take several weeks to completely dry out a flooded area. It is very important to ensure flooded areas are completely dry to ensure that mould does not grow. If the house is not dried out properly, a musty odour, signifying growth of mould, bacteria and other organisms, may remain long after the flood. It is important not to paint over or cover mould as the mould will continue to grow underneath the paint.

  • Drain or mop standing water.
  • Remove waterlogged items from the home when possible.
  • Open doors and windows to ventilate your home.
  • Open closets, drawers and cabinet doors.
  • Circulate air with fans, ideally pushing air out a window or door.
  • Run one or more dehumidifiers as needed.
  • You may need to re-clean several times, surfaces on which mould is growing until the moisture levels no longer support mould growth.
  • Commercial anti-mould sprays are available to control mould growth during the drying phase. One can also mix household bleach and water and lightly spray surfaces using an atomizer (use 60ml (¼ cup) of bleach per litre of water).

Based on:

Alberta Government. Private Sewage and Water Well Systems Recovery and Start Up After a Flood: Cleaning and Sanitizing with Bleach after an Emergency.

CDC. Cleaning and Sanitizing with Bleach after an Emergency.

The City of Calgary. Cleaning up after a flood.

Safe drinking water - Private well owners

When to test well water 

Test your well water once the flood water levels have receded and the well is no longer affected by flood water. There should be no flood water immediately surrounding the well. Before testing your well water it is important to first disinfect your well with a chlorine solution and flush out this disinfectant.  To learn more about disinfecting your well, sampling your well, and your sample results mean visit Ottawa Public Health’s well water information page.

If you need help interpreting the results, please contact Ottawa Public Health at 613-580-6744 and speak with a Public Health Inspector. 

Laundering soiled fabrics
Only wash laundry using water that has been proven safe for use. Your well water should pass two consecutive tests taken at least 48 hours apart before it is used to launder soiled fabrics.
  • Wear rubber gloves and a face mask to protect yourself when handling dirty clothes. 
  • Scrape and shake dirt from fabrics and rinse or wash as soon as possible to prevent mildew growth. 
  • Prewash using cool water and detergent so stains do not set in fabrics.
  • Wash small loads and a full water level.  Do not overload washer. 
  • Wash with hot water and laundry detergent.  Add household bleach according to product label. 
  • A laundromat can be used for washing large quantities of clothes and linens until your onsite waste-water system has been professionally inspected and serviced. 
  • Continue to wash as many times as needed.  If the rinse water is dirty or cloudy, clothes should be washed again until the rinse water is clear. 
  • Dry on the hottest setting once clothes are clean.
  • Store clean clothing in a dry environment to prevent mildew.
Septic systems covered in flood water
The following recommendations are applicable to homes where septic systems are covered with flood waters.
  • Do not use the septic system (i.e., no flushing toilets or draining water from sinks) until water in the septic field is lower than the water level around the house and enough time has been given for the soil to adequately drain. The soil requires additional time to drain in order to allow sewage to be absorbed.  This may take several weeks after flood waters recede. The amount of soil saturation and the time needed to adequately drain the soil will depend on the length of time under water and soil conditions.
  • Your septic system may need to be inspected by a certified private sewage installer before use. The inspection of your septic system should take place after flood water has receded.
  • Avoid compaction of the soil over the septic system during clean up of the site. Do not drive vehicles and equipment over the system during clean-up or restoration activities. Do not set dumpsters or building materials over the system. Fence or mark out the system to protect it while restoration activities take place. Soil is easily compacted when wet. If the soil is compacted in the area of the septic system it may never work again.
  • Do not pump out your septic tank while the soil is saturated. This could cause damage to the tank, the inlet and outlet pipes and connections or it could cause the septic tank to float out of the ground. Even though the soil away from the tank may not appear saturated, the fill soil around the tank may be very saturated and cause even concrete tanks to float.
Backyard clean-up
  • Keep children and pets out of the area until clean-up has been completed.
  • Replace sand in sandboxes and clean any play structures that may have been contaminated.
  • Till garden beds. Do not consume any produce from vegetable gardens impacted by flood water. After re-establishing garden beds, remember to always wash produce before consumption.
  • Properly remediate/clean-up any areas where fluids may have leaked from vehicles such as cars, boats, ATVs, etc.
  • Standing water can pose various health risks (e.g., pails, old tires, or other containers with water can become places where mosquitoes breed) and should be removed.

Based on:

Alberta Government. Private Sewage and Water Well Systems Recovery and Start Up After a Flood: Cleaning and Sanitizing with Bleach after an Emergency.

CDC. Cleaning and Sanitizing with Bleach after an Emergency.

The City of Calgary. Cleaning up after a flood.


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