Floods are usually caused by heavy or prolonged rainfall, but can also occur due to landslides triggered by heavy rainfall or earthquakes, failure of dams, high sea levels at river mouths, coastal storm inundation, and tsunami.
Floods happen often in New Zealand and can cause a lot of damage to buildings and lifeline utilities, as well as injuries and loss of life. Floods can cause major disruption to whānau/family life – you might have to leave your whare/home and you could lose some or all of your possessions - and the emotional impact can be profound. But there are things you can do to reduce the risk and ensure you are prepared.
Usually there will be sufficient warning of a storm, or heavy and prolonged rainfall - but sudden storms and flash flooding can occur without warning.
Find out what the flood risk is in your area. If you live in a flood-prone area, the best thing you can do is prepare yourself, your whare/home and your whānau/family.
If you own a house or another building in a flood-prone area, take these steps to reduce potential flood damage:
✔️ Install non-return valves in drainage pipes, to prevent sewage backing up into the house.
✔️ Reduce water ingress:
- Fit water-resistant door and window frames
- Install ready-made flood defences, such as flood barriers
- Use waterproof sealant on external walls
✔️ On your property’s ground floor, avoid fitted carpets, wooden skirting boards and normal (non water-resistant) plaster. These will be damaged by floodwater and will need replacing. Choose instead ceramic tiles for floor covering and skirtings, and water-resistant lime plaster or cement render and water-resistant paint on internal walls.
✔️ In kitchens and bathrooms, raise cupboards up on stilts, so that water can flow beneath them. Avoid chipboard or MDF units, which will be damaged by floodwater – install stainless steel, plastic or marine plywood kitchen and bathroom units, which can be wiped down after flooding.
✔️ Raise the height of electrical sockets to at least 1.5 metres above ground floor level, to prevent floodwater damage.
✔️ Position any main parts of heating or ventilation systems upstairs or raised well above ground level.
✔️ Purchase a portable pump, or install an automatic pump, to remove flood water. Pumps can keep the floodwater level low inside.
✔️ Review your insurance regularly. Having insurance cover for your home and contents is important to help you get back on your feet if you suffer damage in a disaster.
Find out if your home or business is at risk from flooding and know what you need to do if you have to evacuate.
✔️ Take measures to reduce potential flood damage (see section below)
✔️ Make and practise your emergency plan to get to higher ground
✔️ Make a grab bag and have emergency supplies in case you need to evacuate
✔️ Know what to do with your pets and livestock if you have to evacuate
✔️ Know how to stay informed. Stay up-to-date with the latest weather information from MetService New Zealand and look out for weather watches and warnings which are also available on the MetService mobile app.
Get your whare/home or business ready:
- Move valuable and dangerous items, including electrical equipment and chemicals, as high above the floor as possible. Use watertight containers to store important items.
- Lift curtains, rugs and bedding off the floor.
- Secure outdoor possessions including outdoor furniture and trampolines that can be swept away in floodwaters.
- Clear debris and leaves from external drains and gutters.
- Take photos of your ground floor rooms and outdoor areas, for insurance purposes.
- If you can, attach sheets of waterproof plastic around exterior doors using duct tape.
- Consider using sandbags to keep water away from your house or other buildings.
- Move vehicles to higher ground, or park vehicles in garages, if you can.
- Help neighbours who may need assistance.
Put safety first. Don’t take any chances. Act quickly if you see rising water.
Floods and flash floods can happen quickly. If you see rising water, do not wait for official warnings. Head for higher ground and stay away from floodwater.
Stay out of flood water
Do not try to walk, play, swim, or drive in floodwater: even water just 15 centimetres deep can sweep you off your feet, and half a metre of water will carry away most vehicles. Many flood fatalities are caused by people attempting to drive through water.
Flood water is often contaminated and can make you sick. Make sure you wash your hands, clothes and property after contact with flood waters.
Help others if it is safe to do so, especially people who may require special assistance.
If flooding is possible in your area:
- Be prepared to evacuate and keep your grab bag near.
- Stay informed in an emergency. Listen to emergency services and local Civil Defence authorities. Follow any instructions about evacuation of your area. Self-evacuate if you feel unsafe.
- Move pets to a safe place and move stock to higher ground. If you have to leave, take your pets with you. If it’s not safe for you, it’s not safe for them.
- Turn off water, electricity and gas if advised to.
- Move valuable and dangerous items as high above the floor as possible. This includes electrical equipment and chemicals. Use watertight containers to store important items.
- Lift curtains, rugs and bedding off the floor.
- Check on your neighbours and anyone who may need your help.
If you have been evacuated, it may not be safe to return home even when the floodwaters have receded. Listen to emergency services and local Civil Defence authorities and don’t return home until they tell you it is safe to do so.
Only return home after Civil Defence and emergency services have told you it is safe to do so. It may not be safe to return home even when the floodwaters have receded.
Stay away from damaged areas. You might hamper rescue and other emergency operations and be at further risk from the residual effects of floods.
Look before you step. After a flood, the ground and floors may be slippery or covered with debris, including broken bottles and nails.
Help others if you can, especially people who may need extra help.
If your property is damaged:
- Do not do anything that puts your safety at risk or causes more damage to your property.
- Contact your insurance company as soon as possible.
- If you rent your property, contact your landlord and your contents insurance company.
- Take photos of any damage. It will help speed up assessments of your claims.
Food safety after a flood:
- Throw away food and drinking water that has come into contact with floodwater, including canned goods.
- Avoid drinking or preparing food with tap water until you are certain it is not contaminated. Follow any boil water notice instructions from your local authorities.
- For more information on food safety during and after an emergency visit the Ministry for Primary Industries website.
Cleaning up after a flood
Clean and dry your house and everything in it. Floodwater can make the air in your home unhealthy. When things get wet for more than two days they usually get mouldy. There may also be germs and bugs in your home after a flood.
Mould may make some people with asthma, allergies or other breathing problems sick.
Talk to your doctor or another medical professional if you have questions about cleaning or working in a home that has been flooded. If there is a large amount of mould, you may want to hire professional help to clean up the mould.
Protect yourself by wearing:
- a certified respirator
- protective clothing that covers your arms and legs, and
- sturdy footwear.
Throw away anything that was wet with flood water and can’t be cleaned.
Throw away any wooden spoons, plastic utensils, and baby bottle teats and dummies if they have been covered by floodwater. There is no way to safely clean them.
Disinfect metal pans and utensils by boiling them in clean water.