What Trade Do I Need for a Blocked Drain?

A blocked drain is one of those household problems that can escalate quickly — from a slow-draining sink to a sewage backup on your bathroom floor. In most cases, the answer to "what trade do I need?" is straightforward: a qualified drain cleaner. However, depending on the cause and location of the blockage, other licensed trades may also need to step in. Here's everything you need to know to get the right person on the job.

The Right Trade: Drain Cleaner

A drain cleaner is the primary trade you need for a blocked drain. They have the training, tools, and experience to handle this type of work safely and effectively. Drain cleaners specialise in clearing blockages in both stormwater (surface water runoff) and wastewater (sewage) drain systems — the two main drain types found in NZ homes and commercial properties.

Drain cleaners are typically registered under the Plumbers, Gasfitters and Drainlayers Board (PGDB), which is the licensing authority for drainlaying work in New Zealand. Drainlaying is restricted work under the Plumbers, Gasfitters, and Drainlayers Act 2006, meaning certain tasks — particularly any work that involves breaking into, repairing, or replacing underground drain pipes — must be carried out by, or under the supervision of, a licensed drainlayer. Always ask to see your tradesperson's current PGDB licence before work begins.

What a Drain Cleaner Will Do

A drain cleaner will assess the situation, diagnose the cause, and recommend the best course of action. They will provide a quote for the work before starting. A typical service visit may include:

• Initial assessment — identifying whether the blockage is in the internal pipework, the on-site drain, or the connection to the council main
• CCTV drain inspection — a small camera is fed through the pipe to locate and identify the blockage (tree roots, grease build-up, collapsed pipe, foreign objects, etc.)
• High-pressure water jetting — the most common method for clearing stubborn blockages; a powerful jet of water blasts debris free
• Drain rodding — a mechanical rod is used for simpler, closer blockages
• Reporting — a written report with photos or video footage, especially useful if further repair work is needed

Common Causes of Blocked Drains in NZ

• Tree roots — a very common issue in NZ, particularly with older clay or concrete pipes and large native or exotic trees
• Grease and fat build-up — especially in kitchen drains
• Foreign objects — wet wipes (even "flushable" ones), nappies, sanitary products
• Collapsed or cracked pipes — can occur in older homes or after ground movement
• Stormwater overload — heavy NZ rainfall events, particularly in the north and on the West Coast, can overwhelm stormwater drains
• Sediment and debris — common in outdoor and subfloor drainage

Could Other Trades Be Involved?

Sometimes a job involves multiple trades. Your primary tradesperson can advise if other specialists are needed. Here are the most common situations where additional trades come in:

For internal plumbing fixtures (toilets, sinks, showers), a registered plumber is the appropriate trade. Plumbers and drainlayers are both licensed by the PGDB, and many practitioners hold both licences — so it's worth asking when you call.

NZ Building Code and Compliance

Drain systems in NZ must comply with the NZ Building Code, particularly:

• Clause E1 (Surface Water) — management of stormwater and surface drainage
• Clause G13 (Foul Water) — requirements for sewage and wastewater drainage

For most drain clearing work (unblocking an existing drain without altering the pipe system), a building consent is not required. However, if the drain cleaner discovers that pipes need to be replaced, rerouted, or newly installed, a building consent may be required depending on the scope of work. Always confirm with your local council — consent requirements vary by territorial authority. You can find general guidance at MBIE Building Performance.

Any drainlaying work that is restricted must be carried out by a licensed drainlayer. Doing this work unlicensed is illegal and can void your home insurance.

DIY vs. Professional

For very minor blockages — such as a slow-draining bathroom sink caused by hair build-up — a homeowner can safely try:

• Removing and cleaning the drain cover and trap
• Using a plunger
• Using a drain snake (available from Bunnings or Mitre 10)
• Pouring boiling water down a kitchen drain to shift grease

Do not use harsh chemical drain cleaners repeatedly — they can damage pipes and are hazardous to handle. If a simple DIY attempt doesn't clear the blockage within a short time, call a professional. Persistent blockages almost always indicate a deeper issue that needs proper diagnosis.

Never attempt to break into, cut, or repair underground drain pipes yourself. This is restricted work under NZ law and must be done by a licensed drainlayer.

When to Call a Professional

Call a qualified drain cleaner immediately if you notice:

• Multiple fixtures backing up at once — a sign of a main drain blockage
• Sewage smell inside or outside your home
• Gurgling sounds from toilets or floor drains
• Water pooling in your yard after rain (stormwater drain issue)
• Slow drainage that doesn't respond to basic DIY methods
• Visible sewage overflow — this is a health hazard; call urgently

For rental properties, landlords have obligations under the Healthy Homes Standards to maintain drainage in good working order. Tenants should report blocked drains to their landlord promptly.

How to Choose and Vet the Right Professional

• Check their PGDB licence — search the public register at pgdb.co.nz to confirm they are currently licensed
• Get multiple quotes — always get at least two or three written quotes before agreeing to significant repair work
• Ask about CCTV inspection — a reputable drain cleaner will offer camera inspection for persistent or recurring blockages
• Check reviews — look for local reviews and ask neighbours or your property manager for recommendations
• Confirm what's included — make sure the quote covers call-out, labour, jetting, and any follow-up reporting

You can search for qualified drain cleaners and plumbers in your area right here on tradedirectory.co.nz.

Sources & Further Reading

• Plumbers, Gasfitters and Drainlayers Board (PGDB) — Licence Register
• MBIE Building Performance — Building Consent Information
• Tenancy Services — Healthy Homes Standards
• BRANZ — Drainage and Plumbing Guidance
• WorkSafe NZ — Working Safely Around Drains and Sewage