If your septic tank is playing up, leaking, or just not performing like it used to, it can be really stressful. You're probably thinking: do I need to jump through hoops with the council, or can I just fix it myself?

The truth is, it depends on what exactly needs doing. New Zealand has strict rules around wastewater systems to keep your home safe, protect the environment, and make sure the system lasts as long as possible. But the rules can be confusing, and it’s not always obvious what counts as a “minor repair” versus work that actually needs a building consent.

Let’s break it down in a way that makes sense.

Minor repairs and like-for-like replacements usually don’t need consent

Not all work on your septic system needs a building consent. If you’re just doing a small, like-for-like repair (think replacing a damaged pipe or swapping out a broken component) these types of jobs often fall under “exempt work.”

“Repairing a septic tank effluent disposal system … does not require a building consent as it is considered to be a comparable component.”
— MBIE Building work consent not required guidance, p. 12

This means if your old septic tank is fine but a pipe is leaking, you can often fix it with a comparable replacement without getting council approval. Similarly:

“Replacement of sanitary plumbing and drainage … A building consent is not required as they are replacing an existing sanitary fixture with another comparable fixture in the same position. … Repairing a septic tank effluent disposal system.”
— MBIE Building work consent not required guidance, p. 12

So if you’re literally swapping like-for-like, it’s generally okay. But be careful, this doesn’t mean any replacement is automatically exempt.

Know the limits of exempt work before you start

Exemptions have clear boundaries. Work is not exempt if components fail to meet Building Code requirements:

“Subclause (1) does not include … repair or replacement (other than maintenance) of any component … that has failed to satisfy the provisions of the Building Code …”
— MBIE Building work consent not required guidance, p. 12

This is an important point. If your system is old, broken, or not up to code, you can’t just replace it with something different and hope no one notices. In these cases, a building consent is required.

Another example of the limits:

“Alteration to existing sanitary plumbing in a building, provided that: (a) the total number of sanitary fixtures in the building is not increased by the alteration; and (b) the alteration does not modify or affect any specified system.”
— MBIE Building work consent not required guidance, p. 12

Small tweaks are okay—but anything that changes how the system functions, adds more capacity, or modifies the disposal area is definitely not exempt.

What can happen if you skip consent

There are real cases where building consent or a certificate of acceptance is necessary:

“The plumbing and drainage work was installed … and connects to a septic tank and evapotranspiration bed … The authority refused to grant a certificate of acceptance … because the work did not satisfy the provisions of the Building Code, including Clause G13 Foul water and G14 Industrial liquid waste.”
— MBIE Determination 2019/048

In plain English: someone tried to do work on their septic system without consent, and it didn’t meet the current rules. The council wouldn’t approve it, meaning they could face fines, extra costs, or even having to redo the work.

This shows that the risk isn’t just legal. It’s also about safety, health, and protecting your property.

Why getting consent can save you stress and money

It can be tempting to cut corners if you just want your septic system working again, but there are real benefits to going through the consent process when needed:

• Peace of mind: Knowing your system meets the Building Code and won’t cause leaks, contamination, or health hazards.

• Property value protection: Non-compliant systems can make it harder to sell your home.

• Insurance coverage: Work done without consent can affect claims if something goes wrong.

MBIE puts it simply:

“If in doubt about the compliance of your building work, apply for a building consent before you start the work.”
— MBIE Building work consent not required guidance, p. 12

Simple steps to make septic repairs or replacements easier

Here’s a practical guide for homeowners who are confused about what they can and can’t do:

1. Check your system first: Know whether your septic tank or pipes are just minorly damaged, or if the whole system is failing.

2. Identify the type of work: Is it a simple replacement (like-for-like), or a major repair or upgrade?

3. Look for exemptions: Small repairs to components often don’t need consent. MBIE guidance is clear about this for septic systems.

4. Ask the experts: If you’re unsure, contact your local council or a licensed wastewater professional. It’s always better to be safe.

5. Document everything: Keep records of repairs and replacements, even for exempt work. This protects you if you sell your house or have to prove compliance later.

Red flags that mean you definitely need consent

Here’s a quick checklist for homeowners so you know when council approval is required:

• The system is failing completely: major leaks, overflows, or backing up into the house.

• You’re changing system type or capacity: installing a larger tank, aerated treatment unit, or altering the disposal area.

• Non-compliant or outdated components: pipes or tanks that don’t meet current Building Code standards.

• New connections to public wastewater systems: always requires consent.

• Work affecting the environment: if the effluent area is near waterways or neighbours’ property.

• Any doubt about compliance: MBIE advises that if you are unsure, a building consent should always be applied for.

Following this checklist can save you stress, fines, and potentially dangerous mistakes.

Bottom line

Septic systems and wastewater management are not areas to guess about. Small, like-for-like repairs may not need consent, but anything beyond that could trigger legal requirements. By understanding what counts as exempt work and what requires consent, you can fix your system safely, legally, and with confidence.

Think of it this way: a bit of planning and clarity now saves stress, fines, and extra costs later.

Need advice? We're always happy to help! Get in touch with our team of experts today.