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100+ Free QLD Plumbing Licence Practice Questions

Queensland Plumbing & Drainage Occupational Licence (QBCC) practice questions are available now; exam metadata is being verified.

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2026 Statistics

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 test your QLD Plumbing Licence exam readiness. 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 Practice Questions

Verified exam format metadata for Queensland Plumbing & Drainage Occupational Licence (QBCC) is pending. The practice questions above remain available while official exam length, timing, passing score, fee, and administrator details are reviewed.