ONTARIO ON-SITE SEWAGE SYSTEMS
TECHNICAL EXAMINATION
Practice Examination — 100+ Questions
with ANSWERrs & Rationales 2026
EXAMINATION INSTRUCTIONS
This practice examination is designed to reflect the content and difficulty of the Ontario On-Site Sewage
Systems Technical Examination administered under the Building Code Act, 1992 and the Ontario
Building Code (OBC), specifically Part 8 — Sewage Systems.
Total Questions: 100+ (Multiple Choice, True/False, and Calculation)
Time Allowed: 3 hours (simulated)
Passing Grade: 70%
Permitted Materials: OBC Part 8 reference (for calculation questions)
SECTION A: DEFINITIONS & CLASSIFICATION (Questions 1–15)
1. Under the Ontario Building Code, what is the maximum daily design flow for sewage systems covered
under Part 8?
A) 5,000 litres per day
,B) 10,000 litres per day
C) 15,000 litres per day
D) 20,000 litres per day
ANSWERr: B — Part 8 of the OBC applies to on-site sewage systems with a design capacity of 10,000
litres per day or less.
2. Which Class of sewage system consists of a septic tank followed by a leaching bed?
A) Class 1
B) Class 2
C) Class 3
D) Class 4
ANSWERr: D — A Class 4 sewage system is the most common type, consisting of a treatment unit (septic
tank) connected to a leaching bed constructed in accordance with OBC requirements.
3. A Class 2 sewage system is designed to receive only:
A) Blackwater only
B) Greywater only
,C) Combined blackwater and greywater
D) Industrial wastewater
ANSWERr: B — A Class 2 sewage system is designed only for the treatment and disposal of greywater.
4. What is the maximum daily design flow for a Class 2 sewage system?
A) 500 L/day
B) 1,000 L/day
C) 2,000 L/day
D) 5,000 L/day
ANSWERr: B — A Class 2 sewage system shall not be constructed where the daily design greywater flow
exceeds 1,000 L/day.
5. A Class 3 sewage system refers to:
A) A portable privy
B) A greywater system
C) A cesspool
D) A holding tank
, ANSWERr: C — A Class 3 sewage system is a cesspool.
6. Which of the following is NOT a class of sewage system under the Ontario Building Code?
A) Class 1
B) Class 2
C) Class 5
D) Class 6
ANSWERr: D — The OBC classifies sewage systems as Class 1 through Class 5. There is no Class 6.
7. What is the primary purpose of an on-site sewage system?
A) To store wastewater for later disposal
B) To treat and dispose of domestic wastewater safely
C) To filter drinking water
D) To collect stormwater runoff
ANSWERr: B — The primary function of a septic system is to safely treat and dispose of domestic
wastewater on-site, preventing contamination of groundwater and surface water.
8. What is the minimum vertical separation distance required between the bottom of a leaching bed and
the seasonal high water table?
TECHNICAL EXAMINATION
Practice Examination — 100+ Questions
with ANSWERrs & Rationales 2026
EXAMINATION INSTRUCTIONS
This practice examination is designed to reflect the content and difficulty of the Ontario On-Site Sewage
Systems Technical Examination administered under the Building Code Act, 1992 and the Ontario
Building Code (OBC), specifically Part 8 — Sewage Systems.
Total Questions: 100+ (Multiple Choice, True/False, and Calculation)
Time Allowed: 3 hours (simulated)
Passing Grade: 70%
Permitted Materials: OBC Part 8 reference (for calculation questions)
SECTION A: DEFINITIONS & CLASSIFICATION (Questions 1–15)
1. Under the Ontario Building Code, what is the maximum daily design flow for sewage systems covered
under Part 8?
A) 5,000 litres per day
,B) 10,000 litres per day
C) 15,000 litres per day
D) 20,000 litres per day
ANSWERr: B — Part 8 of the OBC applies to on-site sewage systems with a design capacity of 10,000
litres per day or less.
2. Which Class of sewage system consists of a septic tank followed by a leaching bed?
A) Class 1
B) Class 2
C) Class 3
D) Class 4
ANSWERr: D — A Class 4 sewage system is the most common type, consisting of a treatment unit (septic
tank) connected to a leaching bed constructed in accordance with OBC requirements.
3. A Class 2 sewage system is designed to receive only:
A) Blackwater only
B) Greywater only
,C) Combined blackwater and greywater
D) Industrial wastewater
ANSWERr: B — A Class 2 sewage system is designed only for the treatment and disposal of greywater.
4. What is the maximum daily design flow for a Class 2 sewage system?
A) 500 L/day
B) 1,000 L/day
C) 2,000 L/day
D) 5,000 L/day
ANSWERr: B — A Class 2 sewage system shall not be constructed where the daily design greywater flow
exceeds 1,000 L/day.
5. A Class 3 sewage system refers to:
A) A portable privy
B) A greywater system
C) A cesspool
D) A holding tank
, ANSWERr: C — A Class 3 sewage system is a cesspool.
6. Which of the following is NOT a class of sewage system under the Ontario Building Code?
A) Class 1
B) Class 2
C) Class 5
D) Class 6
ANSWERr: D — The OBC classifies sewage systems as Class 1 through Class 5. There is no Class 6.
7. What is the primary purpose of an on-site sewage system?
A) To store wastewater for later disposal
B) To treat and dispose of domestic wastewater safely
C) To filter drinking water
D) To collect stormwater runoff
ANSWERr: B — The primary function of a septic system is to safely treat and dispose of domestic
wastewater on-site, preventing contamination of groundwater and surface water.
8. What is the minimum vertical separation distance required between the bottom of a leaching bed and
the seasonal high water table?
