ILLINOIS STATE PLUMBING EXAM PRACTICE 2026|2027 QUESTIONS
AND ANSWERS WITH COMPLETE A+ SOLUTIONS!!!
Which type of gas used in plumbing is lighter than air? - Correct Answer -Natural Gas
Piping, fixtures, or equipment installed in a way that interferes with normal operation of windows or
doors shall be: - Correct Answer -Relocated to avoid interference
What is the maximum interval between supports for a vertically installed cast iron pipe? - Correct Answer
-One Story Height
What is the minimum time required for an acceptable test of the water piping system? - Correct Answer -
15 Minutes
What is the minimum clearance required in front of a cleanout? - Correct Answer -18"
The discharge line on a sewage ejector line requires what devices? - Correct Answer -Check Valve
Gate Valve
Union
1|Page
1|Page
,Which factors affect vent size? - Correct Answer -Size of Soil Stack
DFUs Connected
Length of Vent
All vent and branch lines shall be installed so that they drain where? - Correct Answer -Soil or Waste Pipe
Where is copper type M allowed to be installed for water piping? - Correct Answer -Above Ground
Which type of venting applies only to floor drains which depend on siphonage for proper operation? -
Correct Answer -Loop Vent
What is a vent that permits circulation of air in between drainage and vent systems? - Correct Answer -
Relief Vent
What is the name of the point in which impounded liquid will overflow the fixture or receptacle? - Correct
Answer -Flood Level or Flood Rim
2|Page
2|Page
, What is the name of a water supply pipe which extends vertically one full story or more to supply water to
main branches or a group of fixtures? - Correct Answer -Riser
What is determined by measuring from the inside wall of the pipe to the opposite inside wall of the pipe
called? - Correct Answer -Pipe Diameter
What category do Water Heaters, Water Coolers, Drinking Fountains, Heat Exchangers, and Water
Treatment Equipment belong to? - Correct Answer -Plumbing Appliances
What is the term for the measured length along the center line of the pipe and its fittings? - Correct
Answer -Developed Length
What fitting is acceptable for connecting 2 horizontal drain lines? - Correct Answer -Combination Wye and
1/8 Bend
What is the minimum vent size for a 4" trap? - Correct Answer -2"
What is required for a water piping system with a pressure exceeding 80 psi? - Correct Answer -
Pressure Reducing Valve
3|Page
3|Page
AND ANSWERS WITH COMPLETE A+ SOLUTIONS!!!
Which type of gas used in plumbing is lighter than air? - Correct Answer -Natural Gas
Piping, fixtures, or equipment installed in a way that interferes with normal operation of windows or
doors shall be: - Correct Answer -Relocated to avoid interference
What is the maximum interval between supports for a vertically installed cast iron pipe? - Correct Answer
-One Story Height
What is the minimum time required for an acceptable test of the water piping system? - Correct Answer -
15 Minutes
What is the minimum clearance required in front of a cleanout? - Correct Answer -18"
The discharge line on a sewage ejector line requires what devices? - Correct Answer -Check Valve
Gate Valve
Union
1|Page
1|Page
,Which factors affect vent size? - Correct Answer -Size of Soil Stack
DFUs Connected
Length of Vent
All vent and branch lines shall be installed so that they drain where? - Correct Answer -Soil or Waste Pipe
Where is copper type M allowed to be installed for water piping? - Correct Answer -Above Ground
Which type of venting applies only to floor drains which depend on siphonage for proper operation? -
Correct Answer -Loop Vent
What is a vent that permits circulation of air in between drainage and vent systems? - Correct Answer -
Relief Vent
What is the name of the point in which impounded liquid will overflow the fixture or receptacle? - Correct
Answer -Flood Level or Flood Rim
2|Page
2|Page
, What is the name of a water supply pipe which extends vertically one full story or more to supply water to
main branches or a group of fixtures? - Correct Answer -Riser
What is determined by measuring from the inside wall of the pipe to the opposite inside wall of the pipe
called? - Correct Answer -Pipe Diameter
What category do Water Heaters, Water Coolers, Drinking Fountains, Heat Exchangers, and Water
Treatment Equipment belong to? - Correct Answer -Plumbing Appliances
What is the term for the measured length along the center line of the pipe and its fittings? - Correct
Answer -Developed Length
What fitting is acceptable for connecting 2 horizontal drain lines? - Correct Answer -Combination Wye and
1/8 Bend
What is the minimum vent size for a 4" trap? - Correct Answer -2"
What is required for a water piping system with a pressure exceeding 80 psi? - Correct Answer -
Pressure Reducing Valve
3|Page
3|Page
