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Free Practice Questions for QLD Plumbing Licence

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Key Facts: QLD Plumbing Licence Exam

100

Practice Questions

OpenExamPrep

CPC32420

Required Qualification

QBCC

12 months

Minimum Experience

QBCC

AS/NZS 3500

Core Standard Series

Standards Australia

60°C / 50°C

Store / Deliver Hot Water

AS/NZS 3500.4

12 months

Backflow Test Interval

P&D Regulation 2019

The Queensland Plumbing & Drainage Occupational Licence is issued by the Queensland Building and Construction Commission (QBCC) under the Plumbing and Drainage Act 2018 and Plumbing and Drainage Regulation 2019. Licensing is competency-based: applicants complete the CPC32420 Certificate III in Plumbing and demonstrate the required period of licensed experience (generally at least 12 months in the relevant scope) rather than sitting one fixed standalone multiple-choice exam. Core knowledge spans AS/NZS 3500.1 water services, 3500.2 sanitary plumbing and drainage, 3500.4 heated water (60°C storage, 50°C scald-prevention delivery), backflow prevention and hazard ratings, AS/NZS 1547 on-site sewerage, fixtures, gradients and venting, and Queensland legislation and compliance. This free prep includes 100 research-based practice questions with explanations and an AI tutor.

Sample QLD Plumbing Licence Practice Questions

Try these sample questions to review concepts for the QLD Plumbing Licence exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under AS/NZS 3500.2, what is the minimum grade (fall) for a DN 100 sanitary drain?
A.1 in 40
B.1 in 60
C.1 in 90
D.1 in 100
Explanation: AS/NZS 3500.2 sets the minimum grade for a DN 100 drain at 1 in 60, which is approximately 16.7 mm of fall per metre. This grade keeps the flow velocity high enough to be self-cleansing and carry solids without depositing them.
2What is the minimum grade for a DN 150 sanitary drain under AS/NZS 3500.2?
A.1 in 60
B.1 in 80
C.1 in 90
D.1 in 120
Explanation: Larger-diameter drains can run at a flatter grade and still be self-cleansing, so AS/NZS 3500.2 permits a minimum grade of 1 in 90 (about 11.1 mm/m) for DN 150 drains. The larger bore carries the same flow at a lower slope.
3What is the minimum trap seal depth required for a fixture trap under AS/NZS 3500.2?
A.25 mm
B.40 mm
C.75 mm
D.100 mm
Explanation: AS/NZS 3500.2 requires a fixture trap to retain a water seal of not less than 40 mm. This seal forms the barrier that stops foul air and sewer gases from entering the building through the fixture.
4Which Queensland Act is the principal legislation governing plumbing and drainage work in Queensland?
A.Building Act 1975
B.Plumbing and Drainage Act 2018
C.Work Health and Safety Act 2011
D.Water Supply (Safety and Reliability) Act 2008
Explanation: The Plumbing and Drainage Act 2018 is the principal Queensland legislation for plumbing and drainage, supported by the Plumbing and Drainage Regulation 2019 and the Queensland Plumbing and Wastewater Code. It defines regulated work and the licensing and compliance framework administered through the QBCC.
5Which authority administers plumbing and drainage occupational licences in Queensland?
A.Energy Safe Victoria
B.NSW Fair Trading
C.Queensland Building and Construction Commission (QBCC)
D.Australian Skills Quality Authority (ASQA)
Explanation: The Queensland Building and Construction Commission (QBCC) administers plumbing and drainage occupational licences in Queensland, including the occupational plumber and drainer licences. The QBCC also registers notifiable work and oversees compliance.
6Which qualification is the primary technical qualification required for a QBCC occupational plumber licence?
A.Certificate II in Plumbing
B.Certificate III in Plumbing (CPC32420)
C.Certificate IV in Plumbing and Services
D.Diploma of Plumbing
Explanation: The Certificate III in Plumbing (CPC32420), completed through an Australian plumbing apprenticeship, is the core technical qualification the QBCC requires for an occupational plumber licence. At least one year of practical experience after completing the qualification is also typically required.
7Under AS/NZS 3500.1, what is the maximum permissible water velocity in a water service pipe?
A.1.5 m/s
B.2.2 m/s
C.3.0 m/s
D.5.0 m/s
Explanation: AS/NZS 3500.1 limits water velocity in piping to a maximum of 3.0 m/s. Keeping velocity at or below this limit reduces noise, erosion-corrosion of pipe walls and water hammer; good practice often targets around 2.2 m/s.
8A tempering valve on a domestic hot water service to bathroom fixtures must be adjusted so the delivered temperature does not exceed what value?
A.45 degrees C
B.50 degrees C
C.60 degrees C
D.65 degrees C
Explanation: AS/NZS 3500.4 requires heated water delivered to sanitary fixtures used primarily for personal hygiene in normal dwellings to not exceed 50 degrees C, achieved with a tempering valve complying with AS 4032.2. This limits scald risk while still providing adequate temperature.
9Hot water must be stored at a minimum temperature of what value to control Legionella growth under AS/NZS 3500.4?
A.50 degrees C
B.55 degrees C
C.60 degrees C
D.70 degrees C
Explanation: AS/NZS 3500.4 requires heated water to be stored at not less than 60 degrees C to control the growth of Legionella bacteria, which thrive between roughly 20 and 45 degrees C. The water is then tempered down to a safe delivery temperature at hygiene fixtures.
10Which backflow prevention device is required to protect a drinking water supply against a HIGH hazard cross-connection?
A.Dual check valve (non-testable)
B.Single check valve
C.Reduced pressure zone device (RPZD), registered air gap or registered break tank
D.Atmospheric vacuum breaker
Explanation: Under AS/NZS 3500.1, a high hazard (potential to cause death) requires a registered air gap, registered break tank, or a reduced pressure zone device (RPZD). These provide the highest level of protection and, where testable, must be tested at intervals not exceeding 12 months.

About the QLD Plumbing Licence Exam

The Queensland plumbing and drainage occupational licence is issued by the Queensland Building and Construction Commission (QBCC) under the Plumbing and Drainage Act 2018. It is competency-based: applicants complete the CPC32420 Certificate III in Plumbing and demonstrate the required licensed experience rather than sitting a single fixed multiple-choice exam. This free prep targets the trade theory behind that competency — AS/NZS 3500, backflow, on-site sewerage, gradients, and Queensland compliance.

Exam sponsor: Queensland Building and Construction Commission (QBCC). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

No fixed standalone QBCC multiple-choice exam; competency is demonstrated through the CPC32420 qualification (which includes assessed trade theory) plus licensed experience. This practice bank is 100 selected-response trade-theory items.

Time Limit

Not applicable — qualification and experience based

Passing Score

Competency-based (qualification plus required licensed experience)

Exam / Certification Fees

QBCC licence application fee applies (varies by class); no separate standalone exam fee

Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

20%

Sanitary Plumbing & Drainage

AS/NZS 3500.2 drain grades and sizing, inspection openings, grease arrestors, self-cleansing velocity, and water-tightness testing

14%

Water Services

AS/NZS 3500.1 cold-water pipe sizing, minimum residual and maximum static pressure, pressure-limiting valves, and materials

12%

Heated Water Services

AS/NZS 3500.4 heated water: 60°C Legionella storage, 50°C scald-prevention delivery, tempering valves, and TPR relief drains

16%

Backflow Prevention

Hazard ratings, air gaps, dual check valves, DCVAs, RPZDs, backsiphonage vs backpressure, and annual Form 9 testing

16%

Fixtures, Gradients & Venting

Trap seals and minimum seal depth, fixture and drain gradients, vent sizing and terminal location, and trap-seal protection

10%

On-Site Sewerage Facilities

AS/NZS 1547 septic and aerated system design, land application, and setback/buffer distances

12%

QLD Legislation & Compliance

Plumbing and Drainage Act 2018, QBCC licensing, work classification, Form 4 certification, and defect notices

Preparing for the QLD Plumbing Licence Exam

What You Need to Know

  • Passing score: Competency-based (qualification plus required licensed experience)
  • Assessment: No fixed standalone QBCC multiple-choice exam; competency is demonstrated through the CPC32420 qualification (which includes assessed trade theory) plus licensed experience. This practice bank is 100 selected-response trade-theory items.
  • Time limit: Not applicable — qualification and experience based
  • Exam / certification fees: QBCC licence application fee applies (varies by class); no separate standalone exam fee Official sources

Using Our Practice Resources

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

QLD Plumbing Licence: Suggested Study Strategy

1Lock in the core drain grades: DN 100 at 1 in 60 and DN 150 at 1 in 90 under AS/NZS 3500.2
2Remember the hot water pair — store at 60°C for Legionella control, deliver at a maximum of 50°C to personal-hygiene fixtures
3Learn the backflow hierarchy: low hazard = dual check valve, medium = DCVA, high = RPZD / air gap / break tank
4Know the Queensland work classes — permit (compliance assessable), notifiable (Form 4), and minor/unregulated work
5Understand venting: vents equalise pressure to protect trap seals, and terminals must stay clear of openable windows and intakes
6Complete all 100 practice questions and review every miss with the AI tutor before applying for your licence

Frequently Asked Questions

Is there a single QBCC plumbing licence exam in Queensland?

No. Queensland plumbing and drainage licensing is competency-based — you complete the CPC32420 Certificate III in Plumbing (which includes assessed trade theory) and demonstrate the required licensed experience, rather than sitting one fixed standalone multiple-choice exam. This free bank is trade-theory and licensing-knowledge prep.

What qualification and experience do I need for a QLD plumbing licence?

You generally need the CPC32420 Certificate III in Plumbing (or recognised equivalent) plus required licensed experience — typically at least 12 months in the scope of work applied for, after holding a provisional licence. You then lodge an occupational plumber and/or drainer licence application with the QBCC.

Which standards does the QLD plumbing trade theory cover?

Core standards include AS/NZS 3500.1 (water services), 3500.2 (sanitary plumbing and drainage), 3500.4 (heated water), and AS/NZS 1547 (on-site sewerage), all applied under the Plumbing and Drainage Act 2018 and Regulation 2019.

What are the key hot water temperature rules in Queensland?

Hot water must be stored at a minimum of 60°C to control Legionella, then tempered to a maximum of 50°C delivered to personal-hygiene fixtures (baths, basins, showers) in new residential installations to prevent scalding, per AS/NZS 3500.4.

How often must backflow devices be tested in Queensland?

Testable backflow prevention devices and thermostatic mixing valves must be tested at least every 12 months by an endorsed licensed person, who lodges a Form 9 report with the local government under the Plumbing and Drainage Regulation 2019.

Is this free QLD plumbing practice as good as paid prep?

Our 100 practice questions cover the real trade theory behind QBCC licensing — AS/NZS 3500, backflow, on-site sewerage, gradients, venting, and Queensland compliance — with a teaching explanation for every answer plus free daily AI tutor interactions. All content is free forever and updated for 2026.