Management of overflows and bypasses standard
The standard creates a consistent, risk-based framework for managing overflows and bypasses which helps protect public health and the environment.
Overflows occur where pressure on a network exceeds capacity, and untreated wastewater flows onto land (e.g. through manholes) or into waterways. Overflows are a risk to public health and can result in communities not being able to swim or collect seafood in particular areas.
Bypasses are built into the wastewater network to prevent sensitive treatment plant equipment from being damaged during heavy rain.
Currently, wastewater overflow reporting varies across regions, with inconsistent and often incomplete data. This makes it hard to assess network performance nationwide. The new standard is a key step toward improving transparency by introducing consistent monitoring and reporting requirements. It will build a clearer picture of local and national performance to support efforts to reduce overflow events.
The standard:
- creates a nationally consistent consenting pathway for overflows and bypasses, based on a risk-assessment framework
- standardises monitoring and reporting for overflows from wastewater networks.
This standard does not come into force until 19 December 2028. This timing allows operators to use future stormwater and wastewater risk management plans to support consent applications related to overflows and bypasses.
Helpful resources for implementing the standard
We are developing guidance to support the implementation of the management of overflows and bypasses standard. Please email stormwater_wastewater@taumataarowai.govt.nz if you wish to be notified when new guidance material is available.
Controlled activity consent applications
The following are controlled activities under the standard:
- overflows from existing engineered overflow points
- overflows from uncontrolled overflow points
- discharges from bypasses of wastewater treatment plants.
Consent applications for overflows must require:
- mapping of all controlled and uncontrolled overflow points across the network
- risk assessment of each overflow point, categorising them as low, medium or high risk.
Identifying where overflows occur, and their risk profile, helps network operators to address and prevent overflows based on impact and likelihood. It also lays the groundwork for effective monitoring and reporting.
As part of the required risk assessment, network operators must consider:
- impacts on public health
- environmental effects
- effects on affected communities
- likely frequency and volume of overflows.
This assessment helps prioritise management efforts and informs consent conditions.
Consent authorities will retain control over key matters and can impose conditions to:
- avoid, remedy or mitigate environmental and health impacts
- manage odour
- specify actions to reduce overflow frequency and volume over time
- set requirements for monitoring, record-keeping, consultation, reporting and information sharing.
The standard does not establish a consenting pathway for overflow discharges from newly engineered overflow points. These discharges will continue to be regulated under the relevant rules of existing regional plans.
Monitoring and reporting requirements
Consents must include conditions for monitoring and reporting overflow events.
In the event of any overflow or bypass covered by the consent, operators must report:
- the date and time the discharge started
- if the discharge is ongoing
- the approximate duration of the discharge up to the time the information is provided or published
- the approximate volume of wastewater discharged up to the time the information is provided or published
- if the discharge has ceased:
- the approximate duration of the discharge
- the approximate volume of wastewater discharged in the overflow
- information about the actions the consent holder has taken, or intends to take, to remedy or mitigate the discharge or its effects on the environment and any person affected or potentially affected by the discharge
- any public health warning issued as a result of the discharge.
Reporting timeframes
- High-risk bypass or overflow: within 2 hours of becoming aware of the overflow.
- Medium-risk overflow: within 24 hours of becoming aware of the overflow.
- Low-risk overflow: within 48 hours of becoming aware of the overflow.
Information must be shared with the consent authority and any affected communities. It must also be published on an internet site that is publicly available free of charge (such as safeswim.org.nzoutbound) .