Discovering unlicensed drain work during a property sale is more common than many New Zealanders realise — and it can cause serious headaches for both buyers and sellers. In New Zealand, drainlaying is restricted work that must be carried out by a licensed professional, and unpermitted or unlicensed work can have real legal and financial consequences when it comes to light during a sale.
Why Drainlaying Is Restricted Work in New Zealand
Under the Plumbers, Gasfitters, and Drainlayers Act 2006, drainlaying is classified as restricted work. This means only a licensed drainlayer — registered with the Plumbers, Gasfitters and Drainlayers Board (PGDB) — is legally permitted to carry out, supervise, or certify drain work on sanitary drains and stormwater systems connected to the public network.
Homeowners are allowed to do certain minor maintenance on their own property (such as clearing a blocked drain), but any work involving new connections, alterations, or repairs to sanitary or stormwater drainage must be done by a licensed drainlayer. Doing this work yourself or hiring an unlicensed person is illegal and can invalidate your insurance.
How Unlicensed Drain Work Gets Discovered
During a property sale, several processes can bring unlicensed drain work to light:
- Pre-purchase building inspections — A qualified building inspector may identify signs of DIY or non-compliant drainage work.
- LIM reports (Land Information Memoranda) — These council documents show consented work on the property. Drain work that required a building consent but has none will show up as a gap.
- CCTV drain inspections — Buyers increasingly request a camera inspection of the drainage system, which can reveal poor workmanship, illegal connections, or unapproved alterations.
- Council records checks — Solicitors and conveyancers routinely check council records for outstanding consents or code compliance certificates.
What Can Go Wrong for Sellers
If unlicensed drain work is discovered, sellers face a range of potential problems:
- Delayed or failed settlement — Buyers may put the sale on hold or pull out entirely if they're not satisfied the issue will be resolved.
- Price renegotiation — Buyers often use the discovery to negotiate a lower purchase price to cover remediation costs.
- Legal liability — Under the Property Law Act 2007, sellers have obligations around disclosure. Knowingly concealing defects — including unpermitted work — can expose you to legal action after settlement.
- Retrospective consent requirements — Your local council may require you to obtain a building consent retrospectively, which can involve opening up ground, inspections, and significant expense.
- Insurance complications — Home insurance policies may not cover damage arising from non-compliant work, leaving you personally liable.
What Can Go Wrong for Buyers
Buyers who proceed without addressing unlicensed drain work inherit the problem:
- Remediation costs — Fixing or legalising non-compliant drainage can cost anywhere from a few thousand dollars to well over $20,000 depending on the extent of the work, as a rough guide.
- Future sale difficulties — The same issue will surface again when you come to sell.
- Health and safety risks — Poorly installed drains can cause sewage leaks, ground contamination, and structural damage. BRANZ research highlights that drainage failures are a leading cause of moisture-related building damage in New Zealand.
- Council enforcement — Councils have the power to issue notices requiring non-compliant work to be remediated at the owner's cost.
Building Consent and the NZ Building Code
Many drainage alterations require a building consent under the Building Act 2004, in addition to being carried out by a licensed drainlayer. The MBIE Building Performance website outlines what work requires consent and what falls under Schedule 1 exemptions — but exemptions for drainage work are narrow. Always check with your local council before assuming work is exempt.
Compliant drain work must meet the requirements of NZS 4404 (land development and subdivision) and the NZ Building Code clauses G13 (Foul Water) and E1 (Surface Water), among others.
How to Protect Yourself
As a seller:
- Commission a CCTV drain inspection before listing so you know what you're dealing with.
- Obtain retrospective consent and have work certified by a licensed drainlayer if issues are found.
- Be transparent with your solicitor about any work you're aware of.
As a buyer:
- Always request a LIM report and review it carefully with your solicitor.
- Include a CCTV drain inspection as part of your due diligence, especially for older properties.
- Ask the seller to provide producer statements or code compliance certificates for any drainage work.
When to Call a Professional
If unlicensed drain work is discovered — whether you're buying or selling — you should engage a licensed drainlayer immediately to assess the situation. They can advise on what remediation is needed and provide the documentation required to satisfy your council and the other party in the sale. You can find qualified, licensed drainlayers in your area on tradedirectory.co.nz.
For legal advice on disclosure obligations and sale contracts, speak with a property solicitor. For consent queries, contact your local council directly — requirements can vary between territorial authorities.
Safety note: Never attempt to carry out sanitary drain work yourself. Sewage systems carry serious health risks, and unlicensed work is illegal under NZ law. Always use a PGDB-licensed drainlayer.
Certifying Drainlayer
