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Where are rainwater tanks required?
Maintaining tank water quality
Tanks and building consents
Stormwater attentuation tanks

Where are rainwater tanks required?

All new urban premises in the Waikato District are now no longer required to have a rainwater tank under the Water Supply Bylaw.

Rural properties are still required to have a rainwater tank with a minimum size of 22,000L or equivalent of at least 48 hours storage, whichever is greater.

Rainwater tanks are encouraged as they help create a more sustainable water supply and provide storage for non-drinking use.

However, you may need a building consent for your rainwater tank - see below for more details.

If you instead need to connect to a council water supply, see treated drinking water for more information.

Note: that the Waikato District Council Bylaw 2014 came into force on 1 October 2014. The Waikato District Council Water Supply Bylaw 2009 and the Franklin District Council Water Supply Bylaw 2008 were revoked at the time the new bylaw came into force.

Maintaining tank water quality

Poorly-maintained tanks and roof catchment systems increase the risk to public health as they can significantly lower water quality. Preventative measures and corrective actions for safe rainwater harvesting include:

  1. Keeping roof catchments clean of moss, lichen, debris and leaves.
  2. Keeping roof catchments clear of overhanging vegetation, to avoid providing roosting posts for birds; and access for animals, such as rodents and possums.
  3. If appropriate, install gutter guards or screens.
  4. Install screened rain-heads or other debris protection devices on each downpipe. The recommended screen mesh size is 4-6 mm and these should be self-cleaning devices.
  5. Install a first foul flush diverter to prevent contaminated water entering the water tank. These should have automated diversion and drainage systems.
  6. In the event of any weed/chemical spraying in a nearby location, advise the contractor that the roof is used for collecting drinking water. There should not be any overspray reaching the roof. Organ-ochlorine pesticides should not be used.
  7. Prevent access by small animals to the rainwater tanks by screening all inlets and overflows; make sure access hatches are left closed.
  8. Inspect tanks annually and have a professional clean the tanks regularly.
  9. If tank contamination is apparent, the water should be chemically disinfected and boiled before it's used for consumption. Seek advice from a professional.
  10. For more information on maintaining the quality of your drinking water, visit www.drinkingwater.org.nz.

Tanks and building consents

A rain tank will require a building consent if:

  • the tank will supply roof water to the house
  • the Council mains will be plumbed to the tank (eg, backup supply)
  • the tank exceeds 35,000L
  • the tank exceeds 2,000L and is more than two metres above ground or
  • the tank exceeds 500L and is more than four metres above ground.

Unless the tank exceeds the size limits above, installing a rain tank for garden irrigation does not require a building consent.

These criteria apply to both new premises and when retrofitting a tank to an existing property. If a consent is required, it can be included as part of the overall building consent.

Find out more about building consents.

Stormwater attenuation tanks

If you need one of these, it is possible to combine the rainwater tank and stormwater attenuation tank, but the volume of the tank needed should be the sum of the two levels for each function being handled by the combined tank. The top part of the tank drains quickly to buffer storm flows and the bottom saves water for recycling.

 

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