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Add an outdoor water tank

Te whakatū kōpapa wai mō waho

Outdoor tanks store water for use in many applications, both domestic and commercial.

You do not need a building consent for a water tank that is to be used for watering the garden or washing a car, or the structure supporting it, if the tank:

  • does not exceed 500 litres capacity and is supported not more than 4m above the supporting ground
  • does not exceed 1000 litres capacity and is supported not more than 3m above the supporting ground
  • does not exceed 2000 litres capacity and is supported not more than 2m above the supporting ground
  • does not exceed 4000 litres capacity and is supported not more than 1m above the supporting ground
  • does not exceed 8000 litres capacity and is supported not more than 0.5m above the supporting ground
  • does not exceed 16,000 litres capacity and is supported not more than 0.25m above the supporting ground
  • does not exceed 35,000 litres capacity and is supported directly by ground.

All building work must comply with the Building Code.

Using water from a tank

If the stored water is to be used for non-potable sanitary plumbing, flushing toilets and laundry (cold water), an authorised person must carry out this work and a building consent is required.

Where sanitary plumbing is supplied with non-potable water, Watercare services must be notified regarding wastewater charges.

All non-potable water outlets and supply pipes, e.g. a garden hose tap, must be clearly identified as such.

If the stored non-potable water is provided with a network supply connection, to top up when required, a suitable backflow prevention device must be included as part of the installation and a building consent is required.

Water filtration

If you use the stored water for flushing toilets and laundry (cold water), you will need filtration devices.

These devices include a gutter guard, leaf slide and first flush diverter.

Maintaining a water tank

The owner/occupier of the premises must ensure the water tank is maintained in a good operating order and the water is in satisfactory condition.

Stormwater drainage

If the storm water drain is altered to accommodate a store water tank, an authorised person must carry out the work and a building consent is required.

This does not include alterations to a down pipe. This is not required as the detention component would be part of a resource consent requirement, to limit peak flow to the network, in conjunction with a building consent.

If your water tank retains stormwater runoff, before slowly releasing it into the public stormwater system, this is considered drainage work and will require a building consent.

Rainwater intended for use as potable water

If rainwater is intended for potable use, several health and safety-related issues are involved, including treating and disinfecting the rainwater to appropriate water standards and avoiding cross connections.

This requires professional advice.

Rainwater tank resource consent changes

From 1 July 2020 we have temporarily removed resource consent fees for rainwater tank applications for residential properties.  The move is designed to encourage rainwater tank installation during Auckland’s water crisis.

For more information see Rainwater tank installation and maintenance.

How to check if you need a consent to add a water tank

If you are unsure, call us on 09 301 0101 and speak with the building and planning help desk. 

 Online

Our online tool helps you check if you need a building or resource consent for your rainwater tank.

It should take you about 10 minutes to complete.

​Check now

 By phone

09 301 0101

 In person

​At one of our service centres.

More information

For more information, see the MBIE Building Performance website.

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