Floodwater affected buildings


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Floodwater affected buildings

Has your building been affected by floodwaters?

If so, please refer to the Building Research Association of New Zealand's (BRANZ) website link below for guidance on how to deal with buildings that have been effected by floodwater

View BRANZ website information on repairing flood-damaged homes

Do I need a building consent for reinstating flood damaged buildings?

If you need to repair your building and the reinstatement work is like for like then a building consent will not be required. If bracing has been compromised by flood waters then ensure that the reinstatement addresses the replacement of bracing. Any work involving reinstatement of bracing should be carried out by a Licensed Building Practitioner.

Please note that If you are improving or making additions during this process a building consent may be required. You can e-mail the Duty Builder to make enquiries as to whether you need a building consent.

Email Duty Builder

Your insurance company may also require you to apply for a building consent or a certificate of acceptance for repair work so please contact your insurance company before starting any work.

What do I do if my wastewater/septic tank has been compromised by flood waters.

If you suspect your system has been damaged, have the tank inspected and serviced by a professional as it may need to be emptied.

How can you tell if your system is damaged? Signs include: settling, wastewater backs up into household drains and or toilets, the soil in the drain field remains soggy and never fully drains, and/or a foul odour persists around the tank and drain field.

  • Relieve pressure on the septic system by using it less or not at all until floodwaters recede and the soil has drained. For your septic system to work properly, water needs to drain freely in the drain field. Under flooded conditions, water can’t drain properly and can back up in your system. Remember that in most homes all water sent down the pipes goes into the septic system. Clean up floodwater in the house without dumping it into the sinks or toilet.
  • Flooding of the septic tank will have lifted the floating crust of fats and grease in the septic tank. Some of this scum may have floated and/or partially plugged the outlet tee. If the septic system backs up into the house check the tank first for outlet blockage.
  • Clean up any floodwater in the house without dumping it into the sink or toilet and allow enough time for the water to recede. Floodwaters from the house that are passed through or pumped through the septic tank will cause higher flows through the system. This may cause solids to transfer from the septic tank to the drain field and will cause clogging.
  • Prevent silt from entering septic systems that have pump chambers. When the pump chambers are flooded, silt has tendency to settle in the chambers and will clog the drain field if it is not removed. Do not open the septic tank for pumping while the soil is still saturated.
  • Mud and silt may enter the tank and end up in the drain field. Furthermore, pumping out a tank that is in saturated soil may cause it to “pop out” of the ground. (Likewise, recently installed systems may “pop out” of the ground more readily than older systems because the soil has not had enough time to settle and compact.)
  • Do not dig into the tank or drain field area while the soil is still wet or flooded. Try to avoid any work on or around the disposal field with heavy machinery while the soil is still wet. These activities will ruin the soil conductivity.
  • Locate any electrical or mechanical devices the system may have that could be flooded to avoid contact with them until they are dry and clean.
  • Plants, outflow filters, trickling filters, and other media filters have a tendency to clog or damage due to mud and sediment. These systems will need to be back washed, repaired or replanted. Who should I call for help?
  • Septic tank cleaners, Plumbers/Drain layers are the appropriate professionals to contact for any required repairs or maintenance work.

If your system needs replacing due to floodwaters then a building consent or a certificate of acceptance may be required. Check with the Duty Builder to make enquiries as to whether you need a building consent for your proposed work.

Email Duty Builder

Geotechnical concerns

If you have concerns about slope stability or land slips that may compromise you building please call the Council on:
03 520 7400 so further investigation can be arranged.