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Installing and maintaining your rainwater tank

Te whakauru me te pūpuri i tōu kura wai ua

It is important that your water collection point – usually a roof – and your rainwater tank are carefully maintained to avoid contamination.

Possible sources of contamination could include: animal faeces entering the source of the supply; lead flashings and lead-based paint products causing elevated lead levels in collected water; agrichemical spray drifts landing on the roof and being flushed into rainwater tanks with first rains; and the decomposition of leaves. All of these can cause taste or odour issues.

A registered plumber or rainwater tank supplier can advise you on the best location for your rainwater tank.

Do I need consent?

Rainwater for outdoor use

As a general rule you don’t need a building consent if you are installing a rainwater tank for outdoor use only (e.g. garden watering and car washing) and your rainwater tank meets the Building Act requirements.

However, other Building Act standards or our District Plan (go to our Operative plan) could trigger the requirement of a building or resource consent.

The size of your tank could also mean there are boundary set back requirements to consider. The zone you live in (e.g. a heritage zone), is another consideration. These can be checked with our resource consent team.

There could also be private covenants or other agreements that restrict what you can do on your property. Check your title document for this information.

Rainwater for indoor use 

You will need a building consent if you are connecting your rainwater tank to the plumbing of your property (e.g. a toilet or laundry). You need to obtain this consent before you start this work.

A qualified registered plumber will need to join your rainwater tank to the internal plumbing of your dwelling. This ensures the quality of the water supplies as well as protecting the public water supply (by preventing backflow).

You can begin the consent application here

Rainwater tank maintenance

To make sure there are no water quality issues and your rainwater tank is operating at its best, it’s important to carry out maintenance checks regularly. This includes cleaning pre-screening devices, filters and gutters as well as clearing overhanging vegetation around your roof area.  Internal inspections of the rainwater tank and pipework are also required from time to time.

For specific information on the maintenance required for your rainwater tank, check with your rainwater tank supplier or a registered plumber.

Keeping a copy of your rainwater tank manual on site is helpful as well as providing a copy to us.

Tips for roof rainwater tanks

  • Install a first-flush diverter. This is a device that flushes to waste the first 50 to150 litres of water, depending on your roof area. The first runoff usually contains the majority of contaminant, especially after long dry spells.
  • Use plastic pipes.
  • Avoid planting trees beside the house.
  • Clean and disinfect the system every 6 to 12 months including the guttering.
  • A two-tank system is better than one large tank, as the first tank can be used primarily as a settling tank with the second tank being the draw off.
  • The storage tank should be covered to prevent further contamination from animals and birds, and to minimise evaporation losses.

Last updated: 02 Apr 2024 4:35pm