Key questions to work through before installation

These are the practical questions that usually decide the pathway. They are deliberately simple because most customers need a clear starting point before getting into standards, clauses, regional rules or engineering detail.

Understanding the consent pathway - Building consent and resource consent are different

For many projects, there are two separate questions to think about. The first is the building and sanitation side: does the proposed work require building consent, and how will the completed system show compliance with the Building Code? The second is the planning and discharge side: do regional rules, site conditions, or discharge controls trigger a resource consent or a more formal engineering review?

These two pathways overlap, but they are not the same thing. A project may appear straightforward from a product point of view while still needing more careful thought from a site, wastewater, or council-processing point of view.

Do I need building consent for a composting toilet?

In many fixed installations, building consent is commonly part of the pathway unless a specific exemption applies. Building work in New Zealand generally requires consent unless it falls within an exemption, and exempt work still has to comply with the Building Code. That means a composting toilet project still needs to be considered within the legal framework, even where the system is different from a conventional sewered toilet.

There are exemptions for certain plumbing and drainlaying jobs, but they are limited. Some alteration, repair, maintenance, and replacement work may be exempt when it is done by an authorised person. However, those exemptions do not automatically turn a composting toilet project into a simple swap-out exercise. The wider project still needs to be looked at properly.

Sewered sites and alternative toilets

Where a mains sewer connection is available, the legal position needs to be stated carefully. Building Code Clause G13 refers to the drainage system being connected to sewer where a sewer connection is available. That requirement should not be oversimplified into a claim that a sewer-connected property can never include a composting toilet or other non-water-borne toilet arrangement.

New Zealand’s Building Code also recognises non-water-borne disposal, provided it forms part of a healthy and safe disposal system. In practical terms, a sewered site should not be assumed to be limited to flushing toilets only. Once the required sewer connection for the drainage system is addressed, an additional waterless or non-water-borne toilet arrangement may still be workable in some projects, but it needs to be checked carefully against the specific design, use case, Building Code requirements and the relevant council or network-utility position.

Do I need resource consent?

Sometimes yes, sometimes no. Resource consent depends heavily on regional rules, discharge conditions, and the site itself. In some regions, onsite wastewater activities may already sit within a permitted pathway if stated conditions are met. In others, the project may need a more formal application, stronger supporting information, or a clearer engineering case.

That is why one council area may present a relatively direct pathway, while another may be more consent-led. It is also why informal verbal advice from a front counter or a casual phone call is not always the final answer on its own.

Greywater still matters

A composting toilet does not remove the need to think about the rest of the wastewater system. Even where blackwater is reduced or removed, greywater still has to be managed properly. In practical terms, many composting toilet projects are assessed as part of a wider sanitation proposal rather than as a toilet-only decision.

That means the pathway may still depend on how greywater is treated, where it goes, and whether the site conditions support the proposed arrangement. A strong project usually looks at the whole sanitation picture early rather than dealing with the toilet in isolation.

Certification, standards and compliance evidence

Recognised certification and standard-based technical evidence are often what help bridge the gap between product information and a council’s compliance pathway. They do not remove the need to assess the wider project, but they can make the product-level discussion more straightforward and give councils, designers, and consent officers a clearer starting point.

In practical terms, strong product evidence helps separate the product-level question from the site-specific wastewater, building consent and discharge pathway questions. That separation is important because a product-standard certificate may answer one question, while greywater, land application, ventilation, maintenance, user load or regional discharge rules may still need their own supporting information.

In the waterless composting toilet space, the key product-level standard is AS/NZS 1546.2:2008 – On-site domestic wastewater treatment units – Waterless composting toilets. It gives Waterless Composting Toilets a recognised technical benchmark, so the product discussion can be based on evidence rather than marketing claims alone.

The wider sanitation proposal may still need to be considered through AS/NZS 1547:2012 – On-site domestic wastewater management, where relevant to the project. That wider framework is where site conditions, wastewater flows, land application, installation, operation, maintenance, monitoring, and the full project pathway become important.

Who can do the work, and who may need to be involved?

The consent pathway is not just about what is being installed. It is also about who is carrying out the work. Some plumbing and drainlaying work may only sit within exemption pathways when completed by an authorised person. That matters because even where a project looks simple, the work itself may still need to be carried out by the correct licensed or authorised people.

Where the project becomes more site-specific, more technical, or more formal in its pathway, it may also require support from a wastewater engineer, architect, drainlayer, plumber, consent specialist, or a combination of those people.

A practical consent pathway for composting toilet projects

The steps below are a practical way to approach a project before time and cost are locked into the wrong assumptions.

What if the council response is unclear or discouraging?

Not every informal enquiry produces a clear answer. In some cases, early feedback from a council may be cautious, incomplete, or overly simplified. That does not necessarily mean the project cannot proceed. It may simply mean the proposal needs to be framed more clearly, supported by better technical information, or lodged in a more formal way.

Information that may help a consent or council enquiry

The exact information required depends on the council, site and pathway. The following items often help clarify the proposal early.

Saving time and cost in the consent process

In many projects, the most practical way to save time is to identify the likely pathway early and line up the right evidence from the start. That may include product information, site details, wastewater design input, or a clearer description of how the whole sanitation arrangement will work.

Where a project includes other building work, it is often better to think about the sanitation system as part of the wider project rather than as an afterthought. That does not mean every project is complicated. It means the best results usually come when the pathway is treated as part of the design process rather than as a surprise issue at the end.

For architects, wastewater designers, engineers and councils

For professional projects, WCTNZ® can assist with product evidence, council pathway summaries, model-specific documentation, certification references, technical resources and early project scoping. Site-specific design, engineering and consent preparation should still be completed by the appropriate qualified professional.

Useful official references

Other pages of interest

Important limitation

This page provides general information only. It is not legal advice, engineering advice, wastewater design advice, or a substitute for project-specific advice from the relevant council, Building Consent Authority, wastewater designer, engineer, architect, licensed plumber, drainlayer or other qualified advisor involved in your project.

Rules, standards, council practice, interpretations, product evidence requirements and consent pathways can change. Always check the current position for your site and project before relying on general pathway information.