31 Jan 2023 - Public Health Advisory - Avoid flood waters, stream, river and harbour water
Avoid flood waters, stream, river and harbour water
Te Whatu Ora Medical Officer of Health, Dr Ankush Mittal, has issued a community advisory warning in Northland asking people to stay out of waterways, flood waters and harbours and avoid contact with contaminated water. Always assume flood water will be contaminated by sewage.
The advisory follows high rainfall forecast for Northland with a risk of flooding. Up to date information on weather warnings and flood risks can be found at: https://www.metservice.com/warnings/home(external link)
After heavy rainfall, overflow from wastewater systems and other contaminants on land can be washed into our lakes, streams, rivers and coastal waters. Always assume any floodwater is contaminated. These contaminants can cause irritation or infection of our stomach, lungs, skin and eyes and pose a risk to our health.
The advice is to keep out of the water until it is clear (generally five days after the storm ends) and not to consume shellfish or wet fish caught in the storm area. Shellfish can remain contaminated for several weeks and so we advise people to avoid collecting shellfish for at least 28 days after the extreme event or until water testing indicates it is safer to do so. Water quality information is regularly updated at Safe Swim for common sites across Northland: https://safeswim.org.nz/(external link)
If you receive a reticulated water supply, follow any boil water notices from your local council, if they are issued. If you have a self-supply, ensure that your water collection systems remain clear of any debris before and after a severe weather event. If you collect water directed from a natural stream or lake, we advise you avoid water collection during severe rain events and until five (5) days after the storm ends and the water appears and smells clear.
Contaminated food
Floodwater can carry bacteria that can contaminate food.
- Throw away all food and drinking water that has come in contact with floodwater, including things stored in containers. It is impossible to know if containers have been damaged and the seals compromised.
- Do not eat garden produce if the soil has been flooded. Clean up and remove debris and sprinkle gardens with lime.
- Do not eat shellfish from the river mouth or harbour after a flood.
- Follow any boil water notice instructions from your local authorities, if they are issued.
For more information visit the Ministry of Health website: https://www.health.govt.nz/your-health/healthy-living/emergency-management/protecting-your-health-emergency/floods-and-health(external link)
Contact with floodwater
People should avoid floodwater where possible and children should not play in it.
In addition to the danger of drowning and debris, floodwater may also be contaminated with sewage, faecal matter, farm run off and other hazardous materials and objects. There are many potential health risks from this, including gastroenteritis (diarrhoea and vomiting), skin infections and eye infections.
If you have contact with flood water, flooded property or items contaminated with flood water, you should wash your hands with soap and water and dry them thoroughly afterwards. You should also do this after going to the toilet and before preparing or eating any food. Throw away all food and drinking water that has come in contact with floodwater, including things stored in containers.
If you feel unwell after coming into contact with floodwater contact your doctor or call Healthline for free on 0800 611 116.
Preparing and making food
Maintaining hygiene around food preparation and cooking is really important, as surfaces and utensils may have been contaminated during a flood.
- Always wash and dry your hands before preparing food – if water is in short supply, keep some in a bowl with disinfectant.
- Ensure all kitchen utensils and food preparation surfaces are clean before use. Rinse thoroughly in safe water, then disinfect by immersing for 1 minute in a solution of 500 ml (about 2 cups) of plain, unperfumed household bleach in 10 litres of water. Rinse again in safe water. Alternatively, boil all utensils for 1 minute and let cool.
- Decontaminate any surfaces that may have come into contact with floodwater.
- Cook food thoroughly.
- Cover all food with plastic wrap or store in waterproof containers.
- Rubbish containing food scraps must be protected from flies and rats by wrapping the scraps or putting them in a sealed container.
- For more information on food safety visit the Ministry of Primary Industries website: https://www.mpi.govt.nz/funding-rural-support/adverse-events/food-safety-in-natural-disasters-and-emergencies/(external link)
Contaminated Property
If your property is damaged by floodwater, advice on managing any health and safety risks can be found at:
The situation will be reassessed in 24 hours and a further update will be provided.
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