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Key Facts: PGDB Certifying Plumber Exam

100

Practice Questions

OpenExamPrep

65-70

Exam Questions

PGDB

2.5 hours

Time Limit

PGDB

NZD $410

Exam Fee (GST incl.)

PGDB

~75% / 25%

Electronic / Paper Split

PGDB

G12 & G13

Core Building Code Clauses

MBIE / NZBC

The NZ PGDB Certifying Plumber Examination is the Plumbers, Gasfitters and Drainlayers Board registration exam that qualifies a plumber to certify and supervise restricted sanitary plumbing work in New Zealand. It is computer-based via Aspeq, lasting 2.5 hours with 65-70 questions, of which about 75% are answered electronically and 25% on paper diagrams, for a fee of NZD $410. Reference codes and standards are supplied as a PDF in the exam, and the Board recommends 200+ hours of study. Content spans NZBC G12 Water Supplies and G13 Foul Water, AS/NZS 3500.1-3500.4, sanitary plumbing, drainage and venting, hot-water storage and tempering, safe trays, backflow prevention and the PGDB Act 2006. This free prep includes 100 research-based practice questions with explanations and an AI tutor.

Sample PGDB Certifying Plumber Practice Questions

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

1Under the New Zealand Building Code, which clause sets the performance requirements for the safe supply, storage, reticulation and delivery of hot and cold water?
A.Clause E1 Surface Water
B.Clause G12 Water Supplies
C.Clause G13 Foul Water
D.Clause H1 Energy Efficiency
Explanation: NZBC Clause G12 Water Supplies governs the safe supply, storage, reticulation and delivery of potable hot and cold water to fixtures. Acceptable Solution G12/AS1 cites AS/NZS 3500.1 and 3500.4 as compliance pathways.
2Which New Zealand Building Code clause sets the performance requirements for the safe disposal of foul water to prevent illness and loss of amenity from odour?
A.Clause G12 Water Supplies
B.Clause G13 Foul Water
C.Clause E1 Surface Water
D.Clause F4 Safety from Falling
Explanation: NZBC Clause G13 Foul Water requires the safe and hygienic disposal of foul water so people are protected from illness and loss of amenity caused by odour or accumulated matter. G13/AS3 cites AS/NZS 3500.2.
3Under the updated G12/AS1 (from 1 November 2024), what is the maximum temperature at which hot water may be delivered to a sanitary fixture used for personal hygiene in a standard residential dwelling?
A.45 degrees Celsius
B.50 degrees Celsius
C.55 degrees Celsius
D.60 degrees Celsius
Explanation: The updated G12/AS1 lowered the maximum delivery temperature at personal-hygiene fixtures in dwellings from 55 to 50 degrees C to reduce scald risk. A tempering valve or thermostatic mixing valve is required to achieve this.
4G12 requires that water in a hot-water storage system be heated to at least what temperature to control the growth of Legionella bacteria?
A.50 degrees Celsius
B.55 degrees Celsius
C.60 degrees Celsius
D.70 degrees Celsius
Explanation: Stored hot water must reach at least 60 degrees C to control Legionella, which proliferates between roughly 20 and 45 degrees C and is killed at 60 degrees C. The stored water is then tempered down to a safe delivery temperature at the fixture.
5A new mains-pressure hot-water cylinder is installed in a dwelling. What device is required to limit the temperature of water delivered to a bathroom basin and shower to the maximum safe level?
A.An expansion control valve
B.A tempering valve or thermostatic mixing valve
C.A pressure-reducing valve
D.A non-return (check) valve
Explanation: A tempering valve (or thermostatic mixing valve) blends 60 C stored water with cold water to deliver no more than 50 C at personal-hygiene fixtures, as required by G12/AS1. It is mandatory on new and replacement installations.
6Which Australian/New Zealand Standard, cited by G12/AS1, covers the design and installation of water services (cold and hot water supply)?
A.AS/NZS 3500.1 Water services
B.AS/NZS 3500.2 Sanitary plumbing and drainage
C.AS/NZS 3500.3 Stormwater drainage
D.AS/NZS 5601.1 Gas installations
Explanation: AS/NZS 3500.1 Water services is the cited compliance standard for cold-water and water-supply design and installation under G12. AS/NZS 3500.4 covers heated water services.
7Which part of AS/NZS 3500 covers sanitary plumbing and drainage (above-ground discharge of foul water)?
A.AS/NZS 3500.1
B.AS/NZS 3500.2
C.AS/NZS 3500.3
D.AS/NZS 3500.4
Explanation: AS/NZS 3500.2 Sanitary plumbing and drainage is the standard cited by G13/AS3 for the discharge of foul water from sanitary fixtures, covering traps, branches, stacks and venting.
8A sanitary plumbing system is to be hydrostatically tested in accordance with AS/NZS 3500.2. What is the maximum head of water allowable for the test?
A.2 metres
B.3 metres
C.4 metres
D.6 metres
Explanation: Under AS/NZS 3500.2 the hydrostatic test on sanitary plumbing applies a maximum head of 3 metres of water above the highest point being tested, held for the minimum test period to confirm watertightness.
9What is the minimum test duration when hydrostatically testing a sanitary plumbing system to AS/NZS 3500.2?
A.5 minutes
B.10 minutes
C.15 minutes
D.30 minutes
Explanation: AS/NZS 3500.2 requires the hydrostatic (water) test on a sanitary plumbing system to be held for a minimum of 15 minutes so the inspector can confirm no leakage or loss of head.
10Under G13/AS3 and AS/NZS 3500.2, what is the nominal depth of water seal required for a soil-fixture trap?
A.25 mm
B.40 mm
C.50 mm
D.75 mm
Explanation: The nominal depth of water seal for soil-fixture traps is 50 mm (plus or minus 5 mm). Under load testing, the seal must not be reduced below a 25 mm minimum to keep sewer gases out of the building.

About the PGDB Certifying Plumber Exam

The NZ PGDB Certifying Plumber Examination is the national registration exam for plumbers seeking certifying status in New Zealand. It is a computer-based exam of 65-70 questions over two and a half hours, delivered by Aspeq, with about 75% answered electronically and 25% on a paper diagram sheet. It tests NZ Building Code clauses G12 and G13, AS/NZS 3500, hot-water and tempering requirements, backflow prevention, materials and the Plumbers, Gasfitters and Drainlayers Act 2006.

Exam sponsor: Plumbers, Gasfitters and Drainlayers Board (PGDB), delivered by Aspeq. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Computer-based certifying registration exam of 65-70 questions over 2.5 hours via Aspeq; about 75% answered electronically (multiple-choice/single-choice, inline, numerical, multi-select) and about 25% on a paper sheet (drawing and designing on diagrams). This practice bank is 100 selected-response items.

Time Limit

2.5 hours

Passing Score

Approximately 75% (the legacy paper exam used 60 marks); the computer-based pass mark is set by the PGDB

Exam / Certification Fees

NZD $410 (GST inclusive)

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.

16%

NZ Building Code G12 Water Supplies

Potable supply, storage and reticulation, G12/AS1, low-lead products, cross-connection control, pressure/flow and rainwater potability

14%

NZ Building Code G13 Foul Water

Safe foul-water disposal, G13/AS3, trap seals, venting gradients, fixture-unit loading and vent terminal positioning

12%

AS/NZS 3500 Standards Application

AS/NZS 3500.1-3500.4 water, sanitary, stormwater and heated-water services, drain grades, separated systems and on-site wastewater

20%

Sanitary Plumbing, Drainage & Venting

Traps, stacks, venting, air admittance valves, gullies, pipe sizing, testing, grease traps and fire collars

16%

Hot-Water Systems, Tempering & Safe Trays

60 C storage, safe delivery temperatures, tempering valves and TMVs, expansion control, relief discharge, tundishes and safe trays

10%

Backflow Prevention

Hazard rating, device selection (RPZ, double check, dual check, air gap), AS/NZS 2845 and annual testing

6%

Materials & Jointing

Copper, PEX, uPVC, brass and stainless materials, low-lead and AS/NZS 4020 compliance, brazing, soldering, solvent welding and corrosion

6%

PGDB Act & Regulations

PGD Act 2006, registration classes, practising licence, supervision, Certificates of Compliance, discipline and HSWA 2015

Preparing for the PGDB Certifying Plumber Exam

What You Need to Know

  • Passing score: Approximately 75% (the legacy paper exam used 60 marks); the computer-based pass mark is set by the PGDB
  • Assessment: Computer-based certifying registration exam of 65-70 questions over 2.5 hours via Aspeq; about 75% answered electronically (multiple-choice/single-choice, inline, numerical, multi-select) and about 25% on a paper sheet (drawing and designing on diagrams). This practice bank is 100 selected-response items.
  • Time limit: 2.5 hours
  • Exam / certification fees: NZD $410 (GST inclusive) 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

PGDB Certifying Plumber: Suggested Study Strategy

1Get fluent at navigating G12/AS1, G13/AS3 and AS/NZS 3500.1-3500.4 - the exam is effectively open-reference, so speed at finding clauses matters
2Memorise the key temperatures: store at 60 C, deliver no more than 50 C at hygiene fixtures (45 C for schools and vulnerable-user facilities)
3Drill fixture-unit (discharge-unit) values and minimum trap sizes: basin 1/DN32, shower 2/DN40, WC pan 4/DN80, bathroom group 6 units
4Practise the formula-sheet calculations: heat energy (Q = m x c x dT), mixed-water blending, cylinder volume, and drain fall (fall = length / gradient)
5Know the backflow hierarchy cold: high hazard = RPZ/air gap/break tank, medium = double check valve, low/very-low = dual check valve, all testable devices tested annually
6Complete all 100 practice questions and review every miss with the AI tutor before sitting the exam

Frequently Asked Questions

How many questions are on the PGDB Certifying Plumber exam and how long is it?

The certifying plumber examination has 65-70 questions and runs for 2.5 hours. It is computer-based through Aspeq, with about 75% answered electronically and 25% answered on a paper diagram sheet.

What does the PGDB Certifying Plumber exam cost?

The certifying examination costs NZD $410 (GST inclusive). The Board recommends at least 200 hours of study, and reference codes and standards are supplied as a PDF within the exam.

What score do I need to pass the certifying plumber exam?

The legacy paper exam used a pass mark of 60 out of 100. The current computer-based certifying exam pass mark is set by the PGDB and is broadly in the region of 75%; the exact figure is not separately published.

What topics does the PGDB Certifying Plumber exam cover?

It covers NZ Building Code clauses G12 Water Supplies and G13 Foul Water, AS/NZS 3500, sanitary plumbing, drainage and venting, hot-water and tempering requirements, safe trays, backflow prevention, materials and jointing, and the PGD Act 2006.

Who delivers the certifying plumber examination?

The Plumbers, Gasfitters and Drainlayers Board sets the certifying examination, which is delivered as an online computer-based exam by Aspeq at approved exam locations across New Zealand.

Is this free PGDB certifying plumber practice as good as paid prep?

Our 100 practice questions cover the same G12/G13, AS/NZS 3500, hot-water, backflow and PGD Act content as the exam, with a teaching explanation for every answer plus free daily AI tutor interactions. All content is free forever and updated for 2026.