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Rainwater tank installation and maintenance

There are many different rainwater tank options to choose from, and selecting the one right for your needs can be tricky. You also need to consider where your tank will go.

Do I need a consent?

Water for outdoor use: If you are installing a rainwater tank for outdoor use only (garden watering and car washing) and your tank meets the Building Act Exemption 23 requirements, as a general rule, you don’t need a building consent.

However, other Auckland Unitary Plan or Building Act standards could trigger the requirement for a Deemed permitted boundary activity approval, resource consent or building consent. For example, you may need a consent if your tank is too tall, too close to a boundary or in a Special Character Area.

For more information refer to Check if you need a consent and Add an outdoor water tank.

Water for indoor use: If you are connecting your rainwater tank to the plumbing of your property (for example, a toilet or laundry), you will need to obtain a building consent before you do the work.

A qualified, registered plumber will need to install your plumbing joining the rainwater tank to the internal plumbing of your dwelling.

This is to ensure the protection of the public water supply (through backflow prevention) as well as the quality of water supplied by the tank.

For more information refer to Check if you need a consent and Add an outdoor water tank.

Choosing a tank size

The right tank size depends on several factors:

  • what the water will be used for (outdoor, laundry, toilet etc)
  • how much water you can collect from your roof
  • how much space there is for the tank (underground or above ground)
  • the number of household occupants the tank will cater for
  • what your property zone is
  • how reliant you are on water supply.

Generally, the larger the tank, the more effective it will be at capturing a greater volume of roof rainwater runoff and storing it for later use. However, even smaller tanks can provide some household benefits.

There are many tank sizes to choose from, ranging from 200-litre rain barrels (a simple barrel with a tap) to 25,000 litre tanks that connect to internal plumbing for full water supply.

A registered plumber or water tank supplier can offer advice on the best tank to choose and where it should go on your property.

Installation cost

A tank can cost from $200 for a basic rain barrel to around $2000 for a 3000-5000-litre tank, depending on the design and what it is made of. Consenting and installation costs are additional.

Using a water meter on a rainwater tank

Watercare charge each household a fee for collecting and treating their wastewater. This fee covers your contribution to maintaining the wastewater network.

You may need to get a water meter for your rainwater tank if you would like to:
  • use a rainwater tank for 100 per cent of your water needs
  • connect to the wastewater reticulated system.

Our tip

Before installing a water meter, get an estimate for any work from a certified plumber. You can find more information on the Watercare website.

​Rainwater tank maintenance

It is important to maintain a rainwater tank regularly to ensure it is operating as intended and to make sure there are no water quality issues.

Maintenance includes cleaning pre-screening devices, filters, gutters and clearing any overhanging vegetation around your roof area. Periodic maintenance of the tank and pipework, as well as internal inspections, are also required.

Discuss specific maintenance requirements with your tank supplier and/or a registered plumber.

It is recommended you keep a copy of your operation and maintenance manual on site and provide a copy to us for safe record keeping.

Further information

For more information on rainwater tank maintenance, see the operation and maintenance manual that came with your tank, or read our guidance document for on-site stormwater tanks.

​For information on maintaining the quality of your rainwater, see the Ministry of Health's HealthEd website or its website on drinking water publications.

You can also email our Healthy Waters Consenting team if you have questions on rainwater tanks.

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