What to ask a plumber before you hire them
Ten questions every Australian homeowner should ask before signing a plumbing quote. Covers licensing, insurance, WaterMark, compliance paperwork and the red flags that cost homeowners thousands.
Why we wrote this:we run AI receptionists for plumbers across Australia, so we hear hundreds of customer calls a week. We see exactly which plumbers run their business properly and which ones cut corners. These are the ten questions we'd ask if it was our own house.
The 10 questions
1. Are you licensed for the exact work I need?
This sounds obvious but it's where most homeowners trip. Plumbing licences in Australia are scoped — a general plumbing licence does not authorise gas fitting, and gas fitting is a separate ticket. Roofing plumbing, drainage, backflow prevention and mechanical services are also their own classes. If your job involves a gas hot water unit, gas cooktop or gas heater, ask specifically: "Do you hold a current gas fitting licence, and what's the number?" Then check it on the state register. In QLD that's the QBCC, in VIC the VBA, in NSW Fair Trading, in SA it's CBS, in WA the Plumbers Licensing Board. A 30-second lookup saves a $30,000 mistake.
2. Is the quote fixed or hourly?
For 90% of residential jobs — a hot water unit swap, a leaking tap, a blocked drain, a toilet replacement, a tapware install — a competent plumber can give you a fixed price after a quick site look or even photos sent through. Hourly is only acceptable when the scope genuinely can't be known up front (opening a wall to chase a slow leak, drain camera diagnostics where the cause is unknown). If a plumber refuses to fixed-quote a $400 hot water valve replacement, the meter is going to run. Always get the quote in writing with materials, labour, callout fee, GST and disposal costs broken out — never accept a single lump-sum number.
3. Do you provide a WaterMark certificate for the fixtures?
It is illegal for a plumber to install plumbing products in Australia that don't carry a WaterMark certification. The WaterMark scheme is administered by the ABCB and covers everything from taps and toilets to flexi-hoses and backflow valves. If you're supplying your own tapware (from a discount tile shop, a marketplace seller, or imported online), ask the plumber to verify the WaterMark certification before they install. If they refuse to install non-WaterMark gear, that's a green flag — it means they understand they're personally liable if it leaks.
4. What level of public liability insurance do you carry?
$5 million is the bare minimum for residential work, and most decent plumbers carry $10–20M. Ask for a Certificate of Currency — it's a one-page PDF from their insurer — and check the expiry date. If a plumber floods your kitchen, blows a gas line, or causes water damage to a downstairs neighbour's apartment, that policy is what stands between you and a six-figure repair bill. No certificate, no job. A plumber who is annoyed by the question is a plumber whose insurance has lapsed.
5. Will you use WELS-rated fixtures?
WELS (Water Efficiency Labelling and Standards) is mandatory for all taps, showerheads, toilets, urinals, dishwashers and washing machines sold in Australia. The star rating affects your water bill and your home's resale value. Ask the plumber what WELS rating they're proposing. A 4-star vs 1-star showerhead is the difference of about 100,000 litres of water a year for a family of four. A good plumber will recommend WELS-rated fixtures without prompting and tell you the trade-off (e.g. 6-star toilet uses less water but you may need a slightly higher-pressure flush valve).
6. Can you run a drain camera to diagnose, before quoting a dig?
If a plumber tells you they need to dig up your front yard or break up the bathroom slab to find a blockage, stop them. A modern drain camera is a $40–$80 add-on to a normal callout and tells everyone within 15 minutes whether it's tree roots, a fractured pipe, an offset joint or a foreign object. A plumber who skips the camera and goes straight to digging is either ill-equipped or hoping for a much bigger invoice. Always ask: "Can you camera the line first and let me see the footage?"
7. Who's actually doing the work — you or an apprentice?
Apprentice plumbers in Australia must be supervised by a licensed plumber, but in practice, sending an unsupervised apprentice to a residential callout is widespread. Ask straight up: "Will a licensed plumber be on the job for the whole time, or is this an apprentice job with a 5-minute supervisor visit?" You're not being rude — you're asking what you're paying for. If the apprentice is doing 90% of the work, the price should reflect that. And if the apprentice is unsupervised on prescribed work, that's a regulator complaint waiting to happen.
8. What's your after-hours and emergency policy?
A burst flexi-hose at 11pm on a Saturday is the moment you find out whether your plumber is real. Ask up front: "If I have an emergency at 9pm next Tuesday, do you answer? What's the after-hours callout? How long until you can be on site?" A plumber who doesn't answer this clearly is one whose phone goes to voicemail. The best operators have a real receptionist or an AI receptionist that books emergency jobs on the spot — and that's the one you want, because they're also the one who'll turn up when they say they will during the day.
9. Do you lodge the required compliance paperwork?
Most plumbing work in Australia requires a Certificate of Compliance to be lodged with the relevant authority. In NSW it's a Notice of Work / Certificate of Compliance lodged with the local water authority. In VIC it's the Compliance Certificate lodged with the VBA. In QLD it's a Form 4 / Form 9. In SA, CBS. A licensed plumber lodges this as part of the job — don't accept a quote that doesn't mention it. If you ever sell the house, an unlodged certificate can hold up settlement.
10. How do I reach you if there's a problem after the job?
Ask: "If your work fails three months from now, what's the fastest way to get hold of you?" A reputable plumber will hand you a workmanship warranty in writing (12 months minimum, 5–7 years on big-ticket installs is common) and a phone number that actually rings through to a person. A plumber who fobs you off with a generic email address or doesn't want to talk warranty is one who plans to be hard to find when things go wrong. The phone test from before still applies: ring the number after the quote and see who picks up.
Green flags — hire with confidence
- Answers the phone in business hours. Or has a receptionist or AI receptionist that books on the spot.
- Sends a fixed-price quote in writing. Materials, labour, callout, GST and disposal broken out.
- Mentions WaterMark and WELS without being asked. Tells you they understand the rules.
- Hands you a Certificate of Currency. Insurance up to date, no excuses.
- Cameras a drain before digging. Diagnostics first, demolition last.
- Names the warranty period. 12 months minimum, longer on big-ticket installs.
Red flags — walk away if you see these
- Door-knocking plumbers. Real plumbers don't need to door-knock for work.
- Pressure to pay 100% upfront. A 10–30% deposit is fair. Full payment before work starts is not.
- No written quote. "I'll sort it on the day, mate" is how a $300 job becomes a $1,800 invoice.
- No ABN. Check it on abr.business.gov.au.
- Cash-only discount. Means no invoice, no GST, no warranty, no record if things go wrong.
- Refuses to provide insurance certificate. The certificate is one click in their inbox. Refusal means it's expired.
- Wants to dig before cameraing the line. Either under-equipped or over-charging.
- Vague about who's on the tools. If the licensed plumber can't commit to being on site, the apprentice is running the show.
Where to complain if it goes wrong
Every state and territory has a regulator that handles plumbing complaints. Always go to the plumber in writing first and give them a fair chance to fix the issue. If they refuse or go silent, escalate.
- QLD — QBCC (Queensland Building and Construction Commission). Free dispute resolution under $50k.
- VIC — VBA (Victorian Building Authority). Domestic Building Dispute Resolution Victoria handles $10k+ disputes.
- NSW — NSW Fair Trading. Free conciliation, then NCAT for orders.
- SA — CBS (Consumer and Business Services). Free conciliation, then SACAT.
- WA — Plumbers Licensing Board / Building Commission.
- TAS — CBOS (Consumer, Building and Occupational Services).
- ACT — Access Canberra.
- NT — NT Consumer Affairs.
The phone test — why it's the best signal
Ring the plumber's number during business hours, then again at 5pm, then at 7pm. A plumber who picks up — or has a real receptionist or an AI receptionistthat books your job on the spot — has their business sorted. That's the same person who'll turn up when they say they will. A plumber whose phone rings out, or who promises a callback that never comes, is showing you exactly how they'll handle your job. The phone behaviour is a near-perfect predictor of the job behaviour.
For pricing context across Australian capitals, see our Sydney plumber pricing guide — same logic applies in Brisbane, Melbourne, Adelaide and Perth, with a $20–$40 swing depending on the city.
Frequently asked questions
Q: What questions should I ask before hiring a plumber?
Ask about their licence (and the specific class — gas, drainage, roofing), whether the quote is fixed or hourly, public liability insurance level, whether fixtures will be WaterMark and WELS rated, whether they'll camera a drain before digging, who's actually doing the work, after-hours policy, compliance paperwork, and how to reach them after the job.
Q: How do I check if a plumber is licensed in Australia?
Every state has a free public licence register: QBCC (QLD), VBA (VIC), NSW Fair Trading, CBS (SA), Plumbers Licensing Board (WA). Type the plumber's name, business name or licence number into the register. If the licence has expired or is restricted to a different class of work, walk away.
Q: What's the difference between a plumber and a gas fitter?
Different licences. Many plumbers hold both, but a plumbing licence alone does not authorise gas work. If your job involves a gas hot water unit, gas cooktop, gas heater or gas barbecue plumbed to mains, ask specifically whether they hold a current gas fitting licence and request the licence number.
Q: Why does WaterMark certification matter?
It's a federal requirement under the Plumbing Code of Australia. It's illegal to install plumbing products without WaterMark certification. Non-WaterMark fixtures void your home insurance and are a known cause of catastrophic flexi-hose failures.
Q: Should I get more than one quote from a plumber?
Always get three for any job over $500. Three quotes tell you what the fair market price actually is, and which plumber understood your job best. The middle quote is almost always the right one.
Q: What's a fair callout fee for an Australian plumber?
$80–$120 in metro areas during business hours, $150–$250 after-hours. Some plumbers waive the callout if you proceed with the job — ask up front.
Q: What if a plumber's work is faulty after the job?
Contact them in writing first and give them a reasonable chance to fix it. If they refuse or don't respond, escalate to your state regulator: QBCC in QLD, VBA in VIC, NSW Fair Trading in NSW, CBS in SA. For workmanship disputes under $40k, you can also lodge with the relevant state tribunal (QCAT, VCAT, NCAT, SACAT).
Q: Are illustrative reviews and door-knocking plumbers legitimate?
Almost never. Reputable plumbers don't need to door-knock for work or pay for fake reviews. If someone turns up unannounced saying they "noticed an issue", send them on their way and check the licence register for whoever you do call instead.
Looking for a plumber who answers every call?
Ring the live demo — that's an AI receptionist answering, the same one your plumber might use. Hear how fast it qualifies and books a job, then check whether your shortlist plumbers measure up.