Floods are New Zealand’s number one hazard in terms of frequency, losses and declared civil defence emergencies. Floods can cause injury and loss of life, damage to property and infrastructure, loss of stock, and contamination of water and land.

Visit the Get Ready(external link) website for what to do before, during and after a flood strikes your home or business.

Floods are usually caused by continuous heavy rain or thunderstorms but can also result from tsunami and coastal storm inundation. 

Understand the hazards of flooding in Canterbury(external link).


Sandbags can be used during a flood:

  • across doorways for houses on a concrete pad
  • across a garage door
  • to divert water downhill

However, they can’t stop water coming from under the house and through the floorboards or other access points.

Make them out of feed bags, hessian bags or plastic (polypropylene) sacks. If you have only the plastic open weave type bag, put one inside the other. Don’t use kitchen rubbish bags as they will slip around in the water and may split.

Sandbags are available from:

Textile Bag and Sack Company

Address: 55 Byron Street, Sydenham

Phone: (03) 961 3535

Opening hours: 8am to 4.15pm Monday to Friday

  • sandbag diagramFill them with a heavy or sandy soil or with sand. Sand is available from any garden centre.
  • Don’t use gravelly or rocky soils as they will let the water through.
  • It’s easiest if there are two people to fill the bags. One holds the bag and the other shovels the soil or sand in.
  • Only fill it half to two thirds full. This gives the soil or sand room to expand as it holds the water. 
  • Don’t tie or seal the bag – when you put it in place, fold the flap into a triangle and tuck it under the bag.

Place your sandbags lengthwise and parallel to the water flow with the tucked end facing the flow.

If you need more than one row’s height, place the second row crosswise, and the third row lengthwise to strengthen the wall.

When the water has receded, separate your sandbags, lay them out or stand them up and let them dry out thoroughly.

When they are dry, store them for use again. If you leave them wet, they will rot or deteriorate quickly.

To dispose of sandbags scatter the sand in your garden.

Please do not leave on the kerbside as this may clog up the drains.