Rerouting a stormwater drain away from your neighbour's fence is often possible, and in many cases it's a sensible thing to do — poorly directed stormwater can cause fence damage, soggy ground, and neighbourly disputes. However, there are important rules in New Zealand around building consents, licensed drainlayers, and where stormwater can legally discharge. Getting these right from the start will save you headaches down the track.
Why Stormwater Direction Matters
Stormwater runoff from your roof, driveway, and hard surfaces needs somewhere to go. If it's currently directed toward your neighbour's fence line, it can cause:
- Timber fence rot and premature deterioration
- Soil erosion and subsidence near the boundary
- Ponding that may affect your neighbour's property
- Potential legal liability if your drainage causes damage next door
Under the NZ Building Code (specifically Clause E1 – Surface Water), stormwater must be managed so it doesn't adversely affect other properties. So rerouting a drain that's causing problems is not just neighbourly — it may actually be a code compliance issue.
Do You Need a Building Consent?
This is the first question to answer before you pick up a spade. In New Zealand, many minor drainage works are exempt from building consent under Schedule 1 of the Building Act 2004, but the exemptions have limits.
Generally, minor repairs and like-for-like replacements of existing drains may not require consent. However, rerouting a drain — changing its path, adding new connections, or altering where it discharges — is more likely to require a building consent, especially if it connects to the public stormwater network.
Always check with your local council before starting work. Requirements vary between territorial authorities, and some councils have specific rules about stormwater discharge points, soakage systems, and connections to the kerb or street. Your council's building or infrastructure team is the right place to start. You can also find general guidance at MBIE Building Performance.
Is This Restricted Work? Who Can Do It?
In New Zealand, drainlaying is restricted work under the Plumbers, Gasfitters, and Drainlayers Act 2006. This means that connecting to, altering, or extending any drain (including stormwater drains) that connects to the public network must be carried out by — or under the supervision of — a licensed drainlayer.
You can check whether a tradesperson holds a current licence at the Plumbers Gasfitters & Drainlayers Board.
What Can a Homeowner Do?
As a homeowner, you are generally permitted to do drainage work on your own property that does not connect to the public network, provided it is on land you own and you occupy the dwelling. However, the rules are nuanced and the moment your drain connects to a public stormwater drain, a legal point of discharge, or crosses a boundary, a licensed drainlayer must be involved.
In practice, it's safest — and often required — to engage a licensed drainlayer for any rerouting work. A qualified professional will also know your local council's requirements and can certify the work correctly.
Planning Your Reroute: Key Considerations
Before any work begins, think through the following:
| Consideration | What to Check |
|---|---|
| Discharge point | Where will the rerouted water go? Soakage pit, kerb, or council drain? |
| Fall and grade | Stormwater pipes need adequate fall (typically 1:100 minimum) to flow freely |
| Pipe size | Existing pipe diameter may need to match or increase |
| Easements | Are there any drainage easements on your title? Check your LIM or title |
| Neighbour's consent | If work is near the boundary, good communication helps avoid disputes |
| Council connection | Any new connection to the public network needs council approval |
Soakage vs. Piped Discharge
In some situations, redirecting stormwater into a soakage pit or trench on your own property is a practical solution that avoids connecting to the public network. However, soakage systems must be designed to handle the volume of water and suit your soil type — sandy soils drain well, while clay soils may not cope. BRANZ has useful technical guidance on stormwater management for residential properties.
Materials and Pipe Types
For residential stormwater rerouting, uPVC pipe (typically 100mm diameter for downpipe connections) is the standard choice in New Zealand. It's durable, widely available, and easy to work with. You'll find fittings and pipe at Placemakers, Mitre 10, or Bunnings.
Make sure any pipe and fittings used meet the relevant NZ standards — your drainlayer will know what's required.
When to Call a Professional
You should engage a licensed drainlayer for this work if:
- The rerouted drain will connect to the public stormwater network
- A building consent is required
- You're unsure where your current drain discharges
- The work involves digging near existing services (water, gas, electrical cables)
- Your property has a complex drainage layout or is on a sloped site
A licensed drainlayer will assess the job, handle consent paperwork where needed, and ensure the work is done to code. You can find qualified local drainlayers on tradedirectory.co.nz.
Safety note: Always call Before U Dig (0800 248 344) before any excavation to identify underground services. Striking a gas line or electrical cable can be fatal.