Chicago Plumbing Contractor License
Exam (City) Questions and Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the minimum size of a water service pipe for a single-
family residence in Chicago?
a) ¾ inch
b) 1 inch
c) 1¼ inch
d) 1½ inch
b) 1 inch
Rationale: Chicago plumbing code requires a minimum of 1-inch
diameter water service for single-family residences to ensure
adequate flow and pressure.
,2. Which type of pipe is commonly used for underground water
service in Chicago?
a) PVC Schedule 40
b) Copper Type K
c) PEX
d) Cast iron
b) Copper Type K
Rationale: Type K copper is approved for underground water
service in Chicago due to its durability and resistance to
corrosion.
3. What is the maximum allowable distance between supports for
horizontal PVC drain piping?
a) 2 feet
b) 4 feet
c) 6 feet
d) 8 feet
c) 6 feet
Rationale: PVC drain piping must be supported at least every 6
feet horizontally to prevent sagging and maintain proper slope.
4. What is the minimum slope for a 2-inch horizontal drain pipe?
a) 1/16 inch per foot
, b) 1/8 inch per foot
c) 1/4 inch per foot
d) 1/2 inch per foot
c) 1/4 inch per foot
Rationale: Chicago plumbing code requires a minimum 1/4 inch
per foot slope for 2-inch drains to ensure proper gravity flow.
5. Which of the following is an approved venting method for a
kitchen sink?
a) Loop vent
b) Air admittance valve
c) Wet vent
d) All of the above
d) All of the above
Rationale: Chicago code allows loop vents, wet vents, and air
admittance valves as long as they comply with sizing and
installation requirements.
6. What is the minimum pipe size for a vent serving a water closet?
a) 1 inch
b) 1½ inch
c) 2 inches
d) 3 inches
, b) 1½ inch
Rationale: The vent for a water closet must be at least 1½ inches
in diameter to prevent siphoning and maintain proper venting.
7. Which material is prohibited for potable water piping in Chicago?
a) Copper
b) Lead
c) PEX
d) CPVC
b) Lead
Rationale: Lead piping is banned for potable water due to health
hazards; all new installations must use approved materials.
8. How far must a cleanout be installed from a change of direction
greater than 45 degrees?
a) Within 2 feet
b) Within 4 feet
c) Within 6 feet
d) Within 10 feet
b) Within 4 feet
Rationale: Chicago code requires cleanouts within 4 feet of any
change in direction over 45 degrees to allow proper maintenance
access.
Exam (City) Questions and Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the minimum size of a water service pipe for a single-
family residence in Chicago?
a) ¾ inch
b) 1 inch
c) 1¼ inch
d) 1½ inch
b) 1 inch
Rationale: Chicago plumbing code requires a minimum of 1-inch
diameter water service for single-family residences to ensure
adequate flow and pressure.
,2. Which type of pipe is commonly used for underground water
service in Chicago?
a) PVC Schedule 40
b) Copper Type K
c) PEX
d) Cast iron
b) Copper Type K
Rationale: Type K copper is approved for underground water
service in Chicago due to its durability and resistance to
corrosion.
3. What is the maximum allowable distance between supports for
horizontal PVC drain piping?
a) 2 feet
b) 4 feet
c) 6 feet
d) 8 feet
c) 6 feet
Rationale: PVC drain piping must be supported at least every 6
feet horizontally to prevent sagging and maintain proper slope.
4. What is the minimum slope for a 2-inch horizontal drain pipe?
a) 1/16 inch per foot
, b) 1/8 inch per foot
c) 1/4 inch per foot
d) 1/2 inch per foot
c) 1/4 inch per foot
Rationale: Chicago plumbing code requires a minimum 1/4 inch
per foot slope for 2-inch drains to ensure proper gravity flow.
5. Which of the following is an approved venting method for a
kitchen sink?
a) Loop vent
b) Air admittance valve
c) Wet vent
d) All of the above
d) All of the above
Rationale: Chicago code allows loop vents, wet vents, and air
admittance valves as long as they comply with sizing and
installation requirements.
6. What is the minimum pipe size for a vent serving a water closet?
a) 1 inch
b) 1½ inch
c) 2 inches
d) 3 inches
, b) 1½ inch
Rationale: The vent for a water closet must be at least 1½ inches
in diameter to prevent siphoning and maintain proper venting.
7. Which material is prohibited for potable water piping in Chicago?
a) Copper
b) Lead
c) PEX
d) CPVC
b) Lead
Rationale: Lead piping is banned for potable water due to health
hazards; all new installations must use approved materials.
8. How far must a cleanout be installed from a change of direction
greater than 45 degrees?
a) Within 2 feet
b) Within 4 feet
c) Within 6 feet
d) Within 10 feet
b) Within 4 feet
Rationale: Chicago code requires cleanouts within 4 feet of any
change in direction over 45 degrees to allow proper maintenance
access.
