The RBQ 2.4 exam is taken with three documents open on the table, including the regulation that sets the distances, capacities and siting conditions for a septic tank or a soil absorption system. That regulation changed on March 1, 2026. This Prof-RBQ.ca course teaches you to read the text in force, to know which of the three documents to open, and to recognize what the RBQ will not give you.
The RBQ 2.4 exam at a glance
- Length: 3 h; passing grade: 60%.
- Multiple-choice questions, in French or English; the RBQ publishes neither their number nor the weighting of the subjects.
- Four subjects according to the sheet: definitions and types of systems; legislative, normative and regulatory framework; “reading and drawing specifications” (that is, reading plans and specifications); standards and execution of work.
- Only the documents and materials provided by the invigilator may be used (calculator, ruler, paper and pencil supplied on site).
Documents on the exam information sheet (updated April 2024): ✔ provided in the exam room, ✖ recommended reading only.
- ✔ Construction Code (CQLR, c. B-1.1, r. 2)
- ✔ Regulation respecting waste water disposal systems for isolated dwellings (CQLR, c. Q-2, r. 22)
- ✔ Safety Code for the construction industry (CQLR, c. S-2.1, r. 4)
- ✖ Building Act (CQLR, c. B-1.1)
- ✖ Regulation respecting the professional qualification of contractors and owner-builders (CQLR, c. B-1.1, r. 9)
- ✖ Environment Quality Act (CQLR, c. Q-2)
- ✖ Act respecting occupational health and safety (CQLR, c. S-2.1)
What the course contains
- 20 lessons that follow the four exam subjects, each illustrated with diagrams and linked to the free official text on LégisQuébec.
- 684 explained questions in total: 609 in the question bank of the four section quizzes, 86 of them based on a figure (cross-sections of septic tanks and soil absorption systems, site plans, level rod readings), and 75 in the two method quizzes.
- Four section quizzes that draw from this question bank of 609 (25, 20, 15 and 40 questions per attempt).
- A 100-question mock exam drawn from that same question bank, across the four subjects (30, 15, 10 and 45), in 3 hours like the exam.
- Two method quizzes: “Which document do I open?” (30 questions, 10 per attempt in 10 minutes) to choose, among the three documents provided by the invigilator and what must be known without a document, where the rule is, and “Find the section” (45 questions, 15 per attempt in 20 minutes) to quickly find the section in Q-2, r. 22 and the Safety Code for the construction industry.
- 325 flashcards to review definitions, distances, capacities and references.
- 20 audio capsules, one per lesson, to review on the go.
- A free 14-question quiz to see the format before you enrol.
The lessons:
- Principles of private sewage treatment, vocabulary and system types
- The septic tank and primary treatment
- Soil absorption fields, seepage beds and seepage pits
- Above-ground and standard sand-filter beds
- Advanced secondary, tertiary, leaching field and other systems
- Effluent filter, pumping and dosing stations, flow separator, solids pump, pipes and connections
- Choosing and locating: site characterization, permeability, groundwater level, hierarchy of solutions
- EQA, Q-2, r. 22, municipal permit, ministerial authorization and the municipality’s role
- Professionals, engineers, BNQ and standards; the RBQ 2.4 licence and the plumbing boundary
- Reading an installation report I: site, analyses, suggested system
- Reading an installation report II: site plan and elevations
- Planning and organizing the site
- The tripod level: sights, height of instrument, slopes and height differences
- Installing the septic tank
- Installing a pumping or dosing station
- Installing soil absorption fields and seepage beds
- Installing above-ground and standard sand-filter beds
- Installing an advanced secondary or tertiary system
- Completing the work: informing the owner, maintenance, emptying, diagnosis
- Health and safety on a private sewage system site
What generic guides do not explain
Five mechanisms of Q-2, r. 22 and its interfaces that decide a good share of the answers, and that the course works through on concrete cases:
1. The water table can be read in the colour of the soil
Since March 1, 2026, the groundwater level is the seasonally high level of the water table, established in particular by the redoximorphic features of the soil (Q-2, r. 22, s. 1): grey zones and orange mottles keep a record of high water. An exploration pit that is dry on the day of the visit therefore proves nothing. The disposal site of a non-watertight system must lie entirely above this level (s. 7.2), and distances are now measured horizontally.
2. Permeability decides which system you can build
Each type of system has its own list of acceptable soils: soil absorption field or seepage bed in high permeability or permeable soil, seepage pit in high permeability soil, above-ground sand-filter bed down to low permeability soil, standard sand-filter bed in low permeability or impermeable soil (ss. 17, 26, 32, 36 and 40). When two test methods give two levels, the lower one is used, with exceptions (s. 1.1).
3. The signature depends on the building and on the system
For an isolated dwelling, the study and the plan are signed by a professional whose professional order governs the activity; but an above-ground sand-filter bed or a leaching field in soil having a texture in the impermeable zone requires a study by an engineer or a geologist and a plan by an engineer, even for a house (s. 4.3, para. 2). In those cases, as for any building other than an isolated dwelling or a hunting or fishing camp (s. 4.4), the geologist may sign the study, but only the engineer signs the plan. The contractor checks the signature before building.
4. The 3,240-litre threshold is not calculated for a single house
The isolated dwelling is counted in bedrooms (6 or fewer); the 3,240 L/d threshold targets other buildings, camping and caravanning grounds and the groups of s. 3.01 that include an accessory building or another building, and the total daily flow of another building is the sum of the flows of each service in Schedule 1.1 (s. 1.4). A dance and meeting hall with restaurant, 30 seats at 125 L per seat, reaches 3,750 L/d: it falls outside the Regulation and requires an authorization from the Minister under section 22 of the Environment Quality Act.
5. The boundary with plumbing runs through a pipe
Chapter III of the Construction Code applies right into the yard, within the limits of the property (s. 3.02), but it exempts the private sewage disposal system (s. 3.02.01(6)). The drain that feeds the tank remains subject to plumbing when it is connected to the building, and the house sewer must also comply with s. 8 of Q-2, r. 22. Knowing which of the two texts to open is already half the answer.
The editions the course is based on
Our questions were developed from the following editions: Regulation respecting waste water disposal systems for isolated dwellings (Q-2, r. 22), consolidated version updated to July 1, 2026, which includes O.C. 749-2025, in force on March 1, 2026; Safety Code for the construction industry (S-2.1, r. 4), consolidated version updated to July 1, 2026, plus O.C. 817-2026 (in force on August 10, 2026); Construction Code (B-1.1, r. 2), Chapter III, Plumbing (National Plumbing Code of Canada 2020, as amended), consolidated version consulted in October 2026; Environment Quality Act, version updated to August 12, 2026.
The RBQ exam information sheet (updated April 2024) predates the amendment of Q-2, r. 22 that came into force on March 1, 2026 (groundwater level, distances measured horizontally, flood zones). The RBQ may provide an edition other than the one used for our questions: on exam day, read the update date of your copy and work with the text you are given.
The competency profile has not kept pace with the texts: it still designates the regulation by its former number, Q-2, r. 8 (now Q-2, r. 22), and the authorization regime has changed: a system that falls outside this regulation now requires a ministerial authorization under section 22 of the Environment Quality Act. The course teaches the texts in force and points out each discrepancy.
Free official texts: Regulation respecting waste water disposal systems for isolated dwellings; Construction Code; Safety Code for the construction industry (LégisQuébec). The BNQ standards referred to by the Regulation are paid publications: the course reproduces none of their text, tables or figures.
Who this course is for
For candidates sitting the subclass 2.4 exam to act as guarantor. According to the RBQ sheet, this subclass authorizes construction work that is not the exclusive domain of master pipe mechanics and relates to the treatment of building wastewater as well as similar or related construction work. In practice: from the house sewer to the discharge (septic tank, soil absorption systems, sand-filter beds, advanced secondary and tertiary treatment systems, pumping stations). The course also shows where this scope ends: building plumbing, the design and signature of the study and the plan, the electrical supply of the pumps and systems over 3,240 L/d fall to other licence holders or other rules. It also serves licence holders who want to update what they learned before the 2020 and 2026 amendments.
Frequently asked questions
How long is the RBQ 2.4 exam and what is the passing grade?
According to the exam information sheet of the Régie du bâtiment du Québec (RBQ), updated April 2024, the subclass 2.4 exam lasts 3 hours and the passing grade is 60%. It consists of multiple-choice questions and is taken in French or English.
Which documents may I consult during the RBQ 2.4 exam?
Only the documents and materials provided by the invigilator may be used: the Construction Code, the Regulation respecting waste water disposal systems for isolated dwellings (Q-2, r. 22) and the Safety Code for the construction industry, with a calculator, ruler, paper and pencil supplied on site. The other texts on the sheet (the Building Act, the Regulation respecting the professional qualification of contractors and owner-builders, the Environment Quality Act and the Act respecting occupational health and safety) are recommended reading only: they must be understood beforehand.
Which edition of Q-2, r. 22 should I study?
The Regulation was amended by O.C. 749-2025, in force on March 1, 2026: definition of the groundwater level, distances measured horizontally, rules for flood zones. The RBQ sheet (April 2024) predates this change. The course teaches the consolidated text updated to July 1, 2026 and points out what has changed; on exam day, read the update date of the copy you are given.
How many questions are on the exam and how are the subjects weighted?
The RBQ publishes neither the number of questions nor the weighting of the four subjects. Our 100-question mock exam uses a distribution of 30%, 15%, 10% and 45%, based on the number of skills the competency profile assigns to each subject, then adjusted for the density of each.
What does the Prof-RBQ.ca RBQ 2.4 course include?
Twenty lessons and 684 explained questions in total: a question bank of 609 divided into four section quizzes, which a 100-question mock exam also draws from, and 75 questions in two method quizzes, “Which document do I open?” (30 questions, 10 per attempt in 10 minutes) and “Find the section” (45 questions, 15 per attempt in 20 minutes). There are also 325 flashcards and 20 audio capsules, one per lesson. Each explanation names the source behind the answer.
Can I try the course before enrolling?
Yes: a free 14-question quiz, taken from the four exam subjects and including 2 diagrams, shows the format of the questions and explanations of the full course.
Who must sign the characterization study and the site plan?
Since the 2020 overhaul, for an isolated dwelling, the study and the plan are signed by a professional whose professional order governs this activity (Q-2, r. 22, s. 4.3). For an above-ground sand-filter bed or a leaching field built in soil having a texture in the impermeable zone, as for a building other than an isolated dwelling or a hunting or fishing camp, the study is signed by an engineer or a geologist and the plan by an engineer (ss. 4.3 and 4.4). The contractor checks the signature before building.
What is the 3,240-litre-per-day threshold for?
Q-2, r. 22 covers the isolated dwelling, defined by its number of bedrooms (6 or fewer), as well as other buildings and camping and caravanning grounds whose total daily flow of domestic waste water does not exceed 3,240 litres (ss. 1 and 2); the same threshold limits the groups of s. 3.01 that include an accessory building or another building. Above this threshold, the system falls outside the Regulation and must be authorized by the Minister under the Environment Quality Act.
How is the groundwater level defined since March 1, 2026?
It is the seasonally high level of the water table, established through a characterization study using recognized methods, such as observation of the redoximorphic features of the soil (Q-2, r. 22, s. 1), and not the water level on the day of the visit. The joints and openings of a watertight system must be above this level, and the disposal site of a non-watertight system entirely above it (ss. 7.1 and 7.2).
Where does plumbing end and the private sewage system begin?
Chapter III (Plumbing) of the Construction Code also covers plumbing work outside the building, within the limits of the property (s. 3.02), but it exempts the private sewage disposal system (s. 3.02.01(6)), which falls under Q-2, r. 22. The drain that feeds the septic tank remains subject to Chapter III when it is connected to the building, and the house sewer must also comply with s. 8 of Q-2, r. 22: the point of contact is coordinated with the plumber.
How does the course train me to find the right document and the right section?
With two method quizzes. “Which document do I open?” draws 10 questions from 30, in 10 minutes: for each situation, choose among the three documents provided by the invigilator and “No document provided: must be known”. “Find the section” draws 15 questions from 45, in 20 minutes: quickly find the section in Q-2, r. 22 and the Safety Code for the construction industry. The Construction Code is not part of this quiz: the RBQ does not specify the edition provided in the exam room. For the interface with plumbing, look in the table of contents of Chapter III, Plumbing.
Are the questions the same from one attempt to the next?
No. Each section quiz and the mock exam draw their questions at random (from the subject's group, or from all four groups for the mock exam), and the order of the choices may be shuffled: each retake brings largely different questions. The two method quizzes also draw at random from their own group; in “Which document do I open?”, the four choices stay the same from one question to the next.
Why is the RBQ competency profile not enough to study from?
Because part of what it names has changed: it still designates the regulation by its former number, Q-2, r. 8 (now Q-2, r. 22), and a system that falls outside the Regulation now requires a ministerial authorization under section 22 of the Environment Quality Act. The Regulation itself was amended in 2020 (who signs the study and the plan) and in 2026 (groundwater level, distances, flood zones). The course teaches the law in force and points out each discrepancy.
What if the copy of Q-2, r. 22 provided in the exam room predates March 1, 2026?
Read the update date on the first page and answer according to the text provided. The changes of March 1, 2026 (O.C. 749-2025) mainly concern the definition of the groundwater level, the horizontal measurement of distances and flood zones; the course points out each of these changes.
Is Prof-RBQ.ca affiliated with the Régie du bâtiment du Québec?
No. Prof-RBQ.ca is an independent preparation service, not affiliated with the Régie du bâtiment du Québec (RBQ) or the Commission de la construction du Québec (CCQ).
Our approach
The lessons, questions and explanations were written with the help of artificial intelligence tools, then checked against the official texts; in the event of a discrepancy, the official text prevails. The course is a review tool: it replaces neither the texts in force nor the advice of a professional, and it does not guarantee the exam result. Prof-RBQ.ca is an independent preparation service, not affiliated with the Régie du bâtiment du Québec (RBQ) or the Commission de la construction du Québec (CCQ).
