Tree root blockages are one of the most common drainage headaches for NZ homeowners, especially in older properties where clay or concrete pipes have developed cracks that roots can exploit. The good news is that minor root intrusions can sometimes be cleared by hand using a few basic tools and some patience — though more serious blockages will need professional help.
Understanding How Roots Get In
Tree and shrub roots are naturally drawn to the warm, moist environment inside drain pipes. They typically enter through cracked joints, damaged pipe sections, or poorly sealed connections. Once inside, they grow rapidly and can form a dense mat that traps grease, toilet paper, and other debris. Common culprits in NZ gardens include willow, poplar, liquidambar, and even some natives like pohutukawa when planted close to drainage lines.
Before you start, it helps to know what type of pipe you have. Older NZ homes (pre-1980s) often have clay or concrete pipes, which are more prone to cracking and root entry. Newer homes typically use PVC pipe, which is more root-resistant but not immune.
Tools You'll Need
- Drain rods (a set of flexible, screw-together rods with attachments) — available from Bunnings or Mitre 10
- A corkscrew or root-cutting attachment for the rods
- A plunger for initial testing
- Rubber gloves, safety glasses, and old clothing
- A bucket and hose
- A torch for inspecting accessible inspection chambers
Step-by-Step: Clearing Roots by Hand
1. Locate the Blockage
Start by identifying which drain is blocked. Lift the nearest inspection chamber lid (the round or square access point in your yard or driveway) and check the water level. If it's backed up, the blockage is downstream from that point. Work methodically from chamber to chamber to narrow down the location.
2. Assemble Your Drain Rods
Screw the corkscrew or root-cutting head onto the first rod. Feed it into the drain in the direction of flow (towards the street or septic tank). Add rods one at a time as you push further in. Always rotate the rods clockwise as you push — rotating anti-clockwise can cause the sections to unscrew inside the pipe, which creates a much bigger problem.
3. Work Through the Blockage
Apply steady, firm pressure while rotating clockwise. You'll feel resistance when you hit the root mass. Use a push-and-twist motion to break through and cut the roots. This takes time and effort — don't rush it. Withdraw the rods periodically to clear root material from the cutting head.
4. Flush the Line
Once you feel the blockage clear (water should start flowing freely), withdraw all rods carefully. Run a garden hose into the inspection chamber at full pressure to flush the loosened root material through the system. Check the downstream chamber to confirm flow has been restored.
5. Use a Chemical Root Treatment (Optional Follow-Up)
After clearing, some homeowners apply a copper sulphate-based root inhibitor or a foaming root killer to slow regrowth. These products are available at hardware stores. Follow the label instructions carefully — some products are not suitable for use near septic tanks or certain pipe materials. Check with your local council if you're on a public sewer, as some treatments may be restricted.
Important Safety Notes
- Wear gloves and eye protection at all times — drain water contains harmful bacteria.
- Never work in a confined inspection chamber without proper confined space training. If the chamber is deeper than about 1.2 metres, do not enter it — this is a WorkSafe NZ requirement.
- Wash hands thoroughly after any drain work.
- Keep children and pets away from open inspection chambers.
What If It Doesn't Clear?
If drain rods don't shift the blockage after a reasonable effort, the root intrusion is likely too dense, or there may be a collapsed or badly cracked pipe that's trapping roots and debris. At this point, you need professional equipment — typically a high-pressure water jetter or a mechanical drain auger (electric eel).
A licensed drainlayer can also carry out a CCTV drain inspection to see exactly what's happening inside the pipe, which is the only reliable way to assess whether the pipe itself needs repair or replacement.
NZ Building Code and Consent Considerations
Simply clearing a blockage doesn't require a building consent. However, if the pipe is found to be damaged and needs repair or replacement, this is a different matter. Under the NZ Building Code, drainage work that involves replacing or relocating pipes generally requires a building consent and must be carried out by a licensed drainlayer. Some minor like-for-like repairs may fall under Schedule 1 exemptions, but always confirm with your local council before proceeding — rules vary by region.
Drainlaying is restricted work under the Plumbers, Gasfitters, and Drainlayers Act 2006. Only a person registered with the Plumbers, Gasfitters and Drainlayers Board (PGDB) is legally permitted to carry out drainlaying work. Attempting significant drain repairs yourself without a licence is illegal and could affect your home insurance.
When to Call a Professional
Call a licensed drainlayer if:
- Drain rods won't shift the blockage after a genuine attempt
- You notice sewage backing up inside the house
- The inspection chamber shows signs of pipe collapse or significant cracking
- The same drain blocks repeatedly (a sign of ongoing root intrusion or pipe damage)
- You're unsure of the pipe layout or the location of the blockage
You can find qualified, local drainlayers on tradedirectory.co.nz. A professional will have the right equipment to clear the blockage quickly and assess whether the pipe needs repair — saving you time and potential damage to your property.
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