Granny flats and wastewater requirements
New rules allow granny flats (also known as minor residential units) to be built without a resource consent. However, wastewater requirements still apply.
For rural properties where connection to a reticulated wastewater system is not available, the National Environmental Standards for Detached Minor Residential Units states the system must still comply with regional rules. In Bay of Plenty this is the On-Site Effluent Treatment (OSET) Regional Plan.
Connecting to an existing On-Site Effluent Treatment system
If you want to connect a new granny flat to an existing On-Site Effluent Treatment system, you must engage an approved OSET system designer to assess your proposal. They will determine whether the existing system can accommodate the additional wastewater or whether upgrades are required.
Key permitted activity standards include:
- A minimum tank size of 2,700 litres
- Maximum daily discharge of 2,000 litres
- A suitable outlet filter installed
Sufficient land application area to avoid environmental or health effects
If your proposal does not meet the permitted activity standards, you will need to apply to the Regional Council for an On-Site Effluent Treatment resource consent (located under ‘Discharge (including coastal)’.
Installing a stand-alone On-Site Effluent Treatment system for the granny flat
If you want to install a stand-alone system for a granny flat, you must engage an approved OSET system designer to design a fit for purpose system. Depending on the design and location, the system may meet permitted activity limits or require a resource consent.
For permitted systems (whether connecting to an existing system or installing a new stand alone system) the approved designer must prepare a system that meets the permitted activity standards and provide the Schedule 5 On site Wastewater Disposal Site and Checklist to the Bay of Plenty Regional Council.
If you want to discuss permitted activity or resource consent requirements, please contact the Duty Consents Officer on 0800 884 880 or email Consents.Queries@boprc.govt.nz
The associated fees and charges can be found in our Resource Management Act and Building Charges Policy.