Wastewater standards - separating myth from fact

Upgrading New Zealand’s public wastewater infrastructure is one of the most significant challenges facing the country.

A key fact is that much of our wastewater infrastructure is aging and under pressure. Decades of underinvestment, combined with deferred maintenance, mean many publicly owned wastewater systems require significant upgrades. About half of our underground wastewater networks are rated by council owners as in very poor, poor or unknown condition.

Around 60 percent of the 330 publicly owned wastewater treatment plants will need to be reconsented within the next 10 years. Many are already operating on expired resource consents.

This upcoming bow wave of consent renewals is a significant hurdle. The current consenting system can be expensive, protracted and unpredictable, making it difficult for councils to manage long-term infrastructure investment.

One of the roles of the Water Services Authority – Taumata Arowai is to provide national oversight of the environmental performance of water networks. This includes setting national standards and targets and ensuring public transparency about how communities’ wastewater treatment plants and networks are performing.

Late last year, the Authority announced New Zealand’s first national wastewater environmental performance standards. The standards apply to discharges to water and land, application of biosolids to land, and arrangements for overflows and bypasses.

The standards are designed to balance affordability with protections for the environment and public health as well as reduce the uncertainty and cost that has historically accompanied the consenting process. Case studies indicate consenting costs could be reduced by up to 40 percent per treatment plant - that’s around $300,000 to $600,000 - and up to 60 percent for smaller plants. Once granted, consents would last for 35 years which gives owners and operators the certainty they need to invest in better-performing infrastructure.

As the standards begin to be implemented, some questions and misconceptions have emerged. Here are the facts.

Myth: The wastewater standards are a “one-size-fits-all” approach

Fact: Treatment requirements vary depending on environmental risk.

The discharge to water standard takes an “end-of-pipe” approach, where treatment limits depend on the type and sensitivity of the receiving environment.

This is a very common approach internationally – many countries have had national end-of-pipe treatment standards for decades. The approach sets performance requirements on this infrastructure that must be complied with.

Under this approach, more stringent treatment is required in sensitive environments with the strictest limits applying to lakes and estuaries

Conversely, less stringent requirements apply where environmental and public health risks are lower reducing the cost of wastewater treatment while continuing to protect public health and environmental outcomes.

Higher treatment requirements can also apply where there is potential for significant public health or environmental risks, such as shellfish gathering areas.

The standards will give councils a consistent framework for renewing wastewater consents, while still accounting for local environmental sensitivity.

Myth: The standards allow raw or partially treated sewage to be discharged to the open ocean

Fact: Untreated or partially treated sewage would not comply with the treatment limits imposed by the standards.

The standards set treatment limits for:

• total suspended solids
• ammonia, which is toxic to marine life
• pathogens, including enterococci in marine environments to manage the risk to public health.

During the public consultation phase, concerns were raised that the open-ocean discharge category could allow untreated sewage from long ocean outfalls. In response, the Authority sought additional independent technical advice and strengthened the final requirements to address this concern. The supporting technical report is available on the Authority’s website.  See section 5 at pages 20-24.

If a wastewater treatment plant discharges within 4 km of a shellfish bed, additional safeguards apply. A quantitative microbial risk assessment must be undertaken to determine safe pathogen limits. This assessment will set the limits for pathogens (E. coli or enterococci) and in practice, will mean a higher level of treatment will be required in these situations.

Myth: The standards will lower standards and lead to more pollution

Fact: The standards will drive greater national consistency and improve performance overall.

Expert advice commissioned by the Authority showed very high variability in consent conditions across the country. A large number of plants have very few enforceable treatment limits, and no plants had comprehensive limits for all the contaminants addressed by the new standards.

The standards introduce clear, enforceable requirements across the country. This provides consistency where historically wastewater consents have been developed case-by-case, often resulting in widely varying requirements, many of which were unenforceable. This approach received widespread support from both territorial authorities and regional councils, who saw significant value in clear, standardised, and enforceable consent conditions that were imposed nationally.

The standards are designed to strike a practical balance between driving improvements across the industry and ensuring affordability, particularly for operators who are underperforming at present.

Evidence also demonstrates that a high proportion of treatment plants (around 20%) are operating on expired consents for an average of five years – some plants have been on expired consents for over 20 years. Many of these plants will have consent conditions that are decades old and do not reflect modern environmental expectations.

This is being addressed by the standards, which require all plants to have comprehensive treatment as part of a consent. Alongside this, plants will not be able to operate on an expired consent – a two-year limit on this practice is a feature of the standards regime.

The standards also introduce stronger transparency and reporting requirements, including public reporting of compliance and independent auditing of compliance reports.

Together, these measures will increase accountability and public confidence that wastewater standards are always being met. Over time, the Authority expects this transparency to drive continuous improvement in wastewater treatment and better protection of waterways and coastal environments.

Public input remains important. Councils and wastewater operators must continue to engage with communities, including iwi and hapū, on key decisions such as the location of treatment plants or where treated wastewater is discharged.

Myth: The standards are weaker than overseas standards

Fact: The standards use the same regulatory approach used internationally.

The standards set end-of-pipe treatment limits, which is a common regulatory approach used internationally in jurisdictions including the European Union, Australian states, the United Kingdom, Canada and South Africa. The standards are based on a review of treatment limits imposed in these jurisdictions.

The treatment limits in the standards are based on a precautionary approach to environmental and public health impacts. This was a foundational principle set out in the independent technical advice that formed the basis for the standards.

The approach in the discharge to water standard is tailored to the receiving environment the plant is discharging to. The New Zealand framework includes nine treatment categories: five for freshwater discharges, and four for plants that discharge to coastal environments.

Myth: The standards rely on simple screening and dilution

Fact: Modern wastewater treatment is required.

The discharge to water standard imposes treatment limits that are calibrated to the sensitivity of the receiving environment based on modern treatment methods.

Screening and dilution alone would not be sufficient for any plant to meet the treatment limits.

The nine different treatment categories imposed by the discharge to water standard treatment categories and the treatment limits imposed by them, were developed through:

• multiple rounds of independent technical advice, public consultation, and stakeholder testing technical analysis
• comprehensive review of existing New Zealand arrangements
• comparison with international best practice for wastewater treatment.

This ensures the standards are both environmentally robust and practical for operators to implement.

Myth: The standards were rushed through

Fact: The standards were developed through extensive consultation and technical advice and became law on 19 December 2025.

A comprehensive development, technical advice and engagement process underpinned the wastewater standards, beginning in October 2023 when the power to make standards was commenced in the Water Services Act. This included significant input from key stakeholders including councils, wastewater network operators and iwi.

Multiple rounds of independent technical advice informed the standards. Feedback from public consultation and targeted stakeholder engagement helped shape the final design. The engagement that informed the standards is summarised in a report on the Authority’s website.

The supporting independent technical reports are publicly available on the Authority’s website. and includes analysis of how requirements in the standards relate to existing arrangement in New Zealand, as well as international jurisdictions.

Conclusion

The wastewater performance standards provide a consistent national framework that will help councils and network operators plan, fund and deliver much-needed infrastructure upgrades while protecting public health and the environment.

They will help ensure that investment in wastewater infrastructure delivers real, long-term benefits for communities and the environments they value.