Exposing a buried drain pipe is a task many NZ homeowners tackle before calling in a drainlayer — whether you're investigating a blockage, checking for damage, or preparing for a repair. Done carefully, hand-digging to locate and expose a pipe is generally something a homeowner can do. The key is knowing where the pipe runs, using the right tools, and understanding when to stop and call a licensed professional.
Locate the Pipe Before You Dig
Rushing in with a spade is the fastest way to crack a pipe. Before lifting a single sod, spend time locating the pipe's route.
- Check your property's drainage plans. These are often held by your local council or may have been provided when you bought the property. Ring your council's building or infrastructure team and ask for as-built drainage records.
- Look for surface clues. Inspection chamber (IC) lids, slight depressions or lush grass strips in dry weather, and the logical path between fixtures and the street can all hint at where a drain runs.
- Use a drain rod or CCTV camera. A flexible drain rod inserted into a nearby inspection chamber can help you feel the direction of the pipe. Many drainlayers offer a CCTV drain inspection service that maps the pipe's exact route — well worth it before major digging.
- Call Before You Dig (0800 248 344). This free NZ service alerts utility companies so they can mark the location of underground services including water mains, gas lines, and cables. Always do this before any excavation — it's not just good practice, it can be a legal requirement on some sites.
Tools You'll Need
Choose tools that give you control rather than brute force:
| Tool | Best use |
|---|---|
| Spade (flat blade) | Initial topsoil removal away from the pipe |
| Mattock or grubber | Breaking compacted soil |
| Pointing trowel | Close-in work within 300 mm of the pipe |
| Hand scraper or wooden spatula | Final soil removal directly against the pipe |
| Bucket and barrow | Removing spoil without piling it back on the trench |
Avoid using a mechanical digger (excavator or rotary hoe) unless you have a very accurate pipe location confirmed by CCTV or locating equipment — machinery can sever a pipe in seconds.
Step-by-Step: Safe Hand Excavation
1. Mark a safe working zone
Once you know the pipe's approximate route, mark a strip at least 600 mm wide centred on the pipe. This gives you room to work without standing directly over the pipe.
2. Remove topsoil carefully
Dig down with your spade parallel to the pipe run, not across it. Keep your blade angled away from the pipe's centreline. In most NZ residential properties, drains are buried between 300 mm and 900 mm deep, though this varies — go slowly.
3. Switch to hand tools at 300 mm depth
Once you're within roughly 300 mm of where you expect the pipe, put the spade aside. Use a pointing trowel or your hands to scrape soil away. Work along the pipe's length rather than digging straight down onto it.
4. Expose gradually
When you first feel or see the pipe, resist the urge to yank soil away quickly. Gently clear soil from the top and sides first, then carefully work underneath. Most NZ residential drains are uPVC (unplasticised PVC) or earthenware (older clay pipes) — both can crack under point loads or sharp impacts.
5. Support the trench walls
For trenches deeper than 1.5 metres, WorkSafe NZ requires trench shoring or battering (sloping the sides). Even shallower trenches can collapse in loose or wet soil — never work in an unsupported trench that makes you uneasy. Check WorkSafe NZ guidelines before digging deep.
6. Keep the pipe supported
Once exposed, don't leave a long section of pipe hanging unsupported. Use timber offcuts or sandbags to cradle it and prevent stress fractures.
Identifying What You've Found
Once exposed, inspect the pipe carefully:
- uPVC pipe — smooth, grey or white plastic, common in homes built from the 1970s onwards
- Clay/earthenware pipe — terracotta-coloured, often in sections with spigot-and-socket joints, common in pre-1970s homes
- Concrete pipe — grey, heavy, usually in older or larger-diameter drains
Note any cracks, root intrusion, joint separation, or corrosion and photograph everything before backfilling. This information is invaluable for your drainlayer.
What Homeowners Can and Cannot Do
Under the Plumbers, Gasfitters and Drainlayers Board (PGDB) rules, drainlaying work is restricted in New Zealand. A homeowner may carry out drainage work on their own home that they occupy, but the work must still comply with the NZ Building Code (particularly clause E1 – Surface Water and clause G13 – Foul Water) and may require a building consent.
Digging to expose a pipe for inspection is generally fine. However, cutting into, joining, re-routing, or replacing drain pipes is restricted work — it must be done by a licensed drainlayer. Always check with your local council about consent requirements before doing any drainage work beyond simple exposure and inspection. See MBIE Building Performance for guidance on what requires consent.
When to Call a Professional
Call a licensed drainlayer if:
- You cannot confidently locate the pipe before digging
- The pipe is deeper than 1.5 metres
- You find a cracked, collapsed, or root-damaged pipe
- Any repair, replacement, or re-connection is needed
- The drain is near a boundary, shared with a neighbour, or connects to the council main
- You're unsure whether a building consent is required
A qualified drainlayer has the tools, insurance, and legal authority to carry out repairs correctly. You can find licensed local drainlayers on tradedirectory.co.nz.
Certifying Drainlayer
