Installing a rainwater tank is a simple and inexpensive process and provides another source of water that can be used in a number of ways.

Rainwater tanks can significantly reduce the demand on our drinking water supply network. They provide a great source for outdoor water use such as gardening, irrigation or washing your car.

Rainwater tanks can also reduce the amount of stormwater runoff from surfaces like roofs, roads and car parks that drain into our urban waterways.

Rainwater tank benefits

  • Reducing peak demand on our water supply network in times of extremely high water use.
  • Providing another source of water for outdoor use to avoid charges for excess water use.
  • Increasing self-sufficiency.
  • Lowering environmental footprint.
  • Access to surplus water in case of an emergency such as water restriction, fire, or drought.

How rainwater tanks work

Rainwater is generally collected from a roof and stored in a tank.

The size of the tank will depend on a number of factors including how much rainwater you need, what you want to use it for, and how much space you have available at your property.

Many retailers sell rainwater tanks, and tanks less than 500 litres in size may be available at your local hardware store.

Please seek professional guidance to select an appropriate rainwater tank that best suits your needs.

Consenting requirements

Water for outdoor use

A building consent is not usually required for a rainwater tank that is used for watering the garden or washing a car or structure. All rainwater tanks must meet the requirements for capacity and height-above ground, as listed in sub-clauses (a) to (g) of exemption 11.1(external link) of the Building Code. 

Water for indoor use

If you are connecting your rainwater tank to the plumbing of your property, you will require a building approval for the alterations to the water supply, but an exemption may be suitable rather than an actual building consent.

Get in touch with our team at to find out what is required. Once consent is approved, a qualified and registered plumber will need to connect your rainwater tank to your plumbing.

You will also need to check the requirement for a backflow prevention device to ensure the connection is safe and the public water supply system is not compromised. More information on backflow prevention(external link)

Rainwater tank requirements for Bank Peninsula

The Water Supply and Wastewater Bylaw 2022 requires new dwellings to have rainwater tanks within reticulated water supply areas of Akaroa, Duvauchelle, Takamatua, Wainui, Pigeon Bay, Little River, and Birdlings Flat with a minimum capacity of 5000 litres.

Stormwater tank requirements 

On-site rainwater storage is required for all new and redevelopment sites on the hills and where the average site slope exceeds five degrees.

This is required under Schedule 6 of Comprehensive Stormwater Network Discharge Consent (CSNDC(external link)).

Preventing contamination

A first flush diverter can be used to prevent leaves, bird droppings and dust from contaminating your rainwater. It is a simple device that fits onto your tank inlet and prevents the initial contaminated roof runoff from entering the tank when it rains.

If you want to use rainwater for drinking purposes, you will need to disinfect it first. Follow the Ministry of Health guidelines to ensure the quality of collected water is fit for purpose Ministry of Health NZ(external link).

You can find more information on improving the quality of collected rainwater and water disinfection on the Ministry of Health’s  HealthEd website(external link).