Free Plumbing Theory Practice Test 2026

200 questions for City & Guilds 6035 and the Level 3 plumbing apprenticeship: cold and hot water, central heating, drainage, pipework, safety and science. Tuned for mobile. No account needed.

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The Plumbing Theory exam at a glance

Plumbing theory in England is assessed by multiple-choice knowledge tests. On the City & Guilds 6035-02 Level 2 Diploma in Plumbing Studies, each unit (health and safety, scientific principles, common processes, cold water, hot water, central heating, drainage, electrical principles) is an online multiple-choice test, mostly 40 questions in 75 minutes, with a pass mark of about 60%. On the Level 3 Plumbing and domestic heating technician apprenticeship (ST0303), the end-point knowledge test paper 1 is 60 multiple-choice questions in 120 minutes: 36 to pass and 50 for a distinction, followed by an option paper.

Tigertest has 200 Plumbing Theory practice questions with explanations, free to start with no account required.

Who sets it: City & Guilds (6035) and end-point assessment organisations (ST0303)
C&G 6035-02: Online multiple choice per unit, mostly 40 questions in 75 minutes
ST0303 paper 1: 60 questions in 120 minutes, 36 to pass, 50 for a distinction
Pass mark: About 60% (City & Guilds); 36 of 60 (ST0303)
Rules used: Approved Documents G, H and L, HSE guidance (England)

Updated November 2026 by the Tigertest team. Practice questions follow the City & Guilds 6035-02 handbook (v5.12, September 2026) and the ST0303 v1.2 end-point assessment plan, checked November 2026. Exam rules change, so confirm current details with Skills England: Plumbing and domestic heating technician (ST0303).

How It Works

Train, Then Test

Five training sets, from Health, Safety & Science to Sanitation, Drainage & Rainwater. Master a topic, then take a test. Questions you miss come back until you have mastered them.

Practice Tests

Four 50-question practice tests across every topic, with a 60% pass line like the real unit tests and an explanation of the right answer on every question.

Built on the 6035 Units and the Apprenticeship Knowledge Test

The practice tests are weighted like the City & Guilds 6035-02 unit tests, with central heating, hot and cold water and safety carrying the most questions. Every question is original and written for England's Approved Documents and HSE guidance.

Health & Safety12%

Scientific Principles10%

Common Plumbing Processes12%

Cold Water Systems12%

Domestic Hot Water Systems12%

Central Heating Systems16%

Sanitation & Drainage10%

Rainwater Systems4%

Electrical Principles6%

Environmental Technologies6%

For Course Tutors

Teaching plumbing at a college or training centre? Set Tigertest as practice between sessions at tigertest.io/teach and see which topics your learners miss most before their unit tests. It is free for you and your learners.

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How to Pass Your Plumbing Theory Tests

1. Learn the systems, not just the parts

Most questions describe a system and ask what happens: why a cold feed is sized as it is, what a motorised valve does in an S plan, why a trap seal is lost. Draw each system from memory until you can label every part.

2. Know the key numbers

Learn the figures that come up again and again, such as stored hot water at 60°C, distribution at 50°C or above, trap seal depths, fall on drainage and the 1 m ladder rule, so you do not lose time on them.

3. Practise the science and sums

Expect questions on pressure and head, heat transfer, expansion, electrical units and simple heat loss sums. Write out the formula, put in the numbers and check the unit.

4. Fix your misses, then retest

Tigertest tracks your accuracy by topic. Aim for 80 percent on every practice test before the real one, then retrain your weakest topic.

Plumbing Theory Frequently Asked Questions

What does the plumbing theory test cover?

Health and safety, scientific principles, pipework and jointing, cold and hot water systems, central heating and controls, sanitation and above-ground drainage, rainwater, electrical basics for plumbers and an awareness of heat pumps and solar thermal. Those are the units of the City & Guilds 6035 Level 2 Diploma and the core knowledge of the Level 3 apprenticeship.

How many questions are on the real tests and what is the pass mark?

Each City & Guilds 6035-02 unit test is an online multiple-choice test, mostly 40 questions in 75 minutes, passing at about 60%. The ST0303 apprenticeship knowledge test paper 1 is 60 questions in 120 minutes: 36 to pass, 50 for a distinction.

Is this the gas or unvented exam?

No. Gas (ACS CCN1), unvented hot water storage and the Water Regulations each have their own practice test on Tigertest. This one covers general plumbing and heating theory and touches those only lightly.

Which rules are the questions based on?

England: Approved Documents H, G and L, HSE guidance on legionella, ladders and asbestos, and RIDDOR. Wales, Scotland and Northern Ireland have their own building regulations, so check local figures there.

Are these the real City & Guilds questions?

No. Every question here is written by Tigertest from the published units and the rules they cover, without copying past papers, sample tests or commercial question banks.

I teach a plumbing course. Can my students use Tigertest?

Yes, for free. Make a class at tigertest.io/teach, post one link, and students join with just their name. You see who practised, their test scores and the topics your class misses most.

Plumbing Theory sample questions and answers

6 of the 200 practice questions, one from each topic, with the answer explained.

1. Approved Document L says the size of a new space heating system should be based on:
- A.The size of the gas meter
- B.A heat loss calculation
- C.The old boiler's rating
- D.The number of radiators
Answer: B. AD L paragraph 5.8 asks for heating to be specified from a heat loss calculation and a recognised sizing method, and says systems should not be significantly oversized.
2. Which fluid category is wholesome water supplied by a water undertaker?
- A.Category 2
- B.Category 3
- C.Category 5
- D.Category 1
Answer: D. Fluid category 1 is wholesome water from the undertaker's mains. Higher categories are progressively more contaminated, up to category 5, which includes water containing human waste.
3. Where hot and cold taps are fitted to a sanitary appliance, Approved Document G says the hot tap should be:
- A.On the left
- B.On the right
- C.Nearest the wall
- D.Mounted higher
Answer: A. AD G paragraph 4.7 says the hot tap should be on the left. A consistent layout helps prevent scalds, especially for people with sight loss.
4. Which Part of the Building Regulations in England covers electrical safety in dwellings?
- A.Part G
- B.Part H
- C.Part P
- D.Part L
Answer: C. Part P covers electrical safety in dwellings and sets which work must be notified. Part L covers energy, Part G sanitation and hot water, and Part H drainage.
5. Greywater re-use systems collect water from:
- A.Roof gutters and downpipes
- B.Kitchen dishwashers only
- C.Baths, showers and basins
- D.WCs and urinals
Answer: C. Greywater is lightly used water from baths, showers and basins, treated for uses such as WC flushing. Water from WCs is foul (black) water.
6. A round blue safety sign with a white symbol tells you:
- A.Something you must do
- B.Something you must not do
- C.A hazard to look out for
- D.Where first aid is kept
Answer: A. Blue circular signs are mandatory, such as wear eye protection. Red circles with a bar prohibit, yellow triangles warn and green signs show safe conditions such as first aid.

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