EXPERT PLUMBING SYSTEMS
CERTIFICATION EXAM (2026
Edition)|||| questions and answers
with rationales/graded A+/2026
update/100% correct /instant
download
Exam Code: EPX-2026
Total Questions: 80
Time Limit: 180 minutes
Passing Score: 75% (60 correct)
Instructions: Select the best answer for each question. Correct answers
are highlighted in bold with rationale provided.
SECTION 1: CODES, SAFETY, AND PROFESSIONAL PRACTICE (Q1–15)
Q1. According to the 2026 IPC, what is the maximum vertical distance allowed for
a fixture drain without venting?
a) 4 ft
b) 6 ft
c) 8 ft – Rationale: 2026 update maintains 8 ft for most fixtures to prevent trap
siphonage, except water closets (6 ft).
d) 10 ft
Q2. A plumbing permit is NOT required for:
a) Replacing a toilet flapper – Rationale: Minor repairs like flappers, washers, or
aerators are exempt; replacing the entire toilet requires a permit.
b) Installing a water heater
c) Adding a bathroom sink
d) Modifying a DWV branch line
,Q3. What is the minimum clearance in front of a commercial water heater for
service access (2026 IRC/IBC)?
a) 18″
b) 24″ – Rationale: 24″ working clearance is required for electrical panels and
water heater access; some jurisdictions raised to 30″ in 2026 for heat pump units.
c) 30″
d) 36″
Q4. Which material is NOW prohibited for domestic water supply lines in most US
jurisdictions (2026)?
a) PEX-A
b) CPVC
c) Lead-containing solder – *Rationale: “Lead-free” means ≤0.25% weighted
average; lead solder banned federally since 1986, but 2026 codes reinforce zero
tolerance.*
d) Brass fittings
Q5. A backflow prevention device is required on:
a) Hose bibb with chemical injector – Rationale: High hazard (chemicals)
requires RPZ; a standard hose bibb without chemicals needs only a vacuum
breaker.
b) Toilet supply line
c) Kitchen sink faucet
d) Washing machine box
Q6. The maximum fixture unit (DFU) load for a 4″ horizontal drainage pipe at 1/8″
per foot slope is:
a) 90 DFU
b) 180 DFU – *Rationale: 2026 tables unchanged; 4″ @ 1/8″ slope = 180 DFU;
1/4″ slope = 216 DFU.*
c) 216 DFU
d) 300 DFU
Q7. What is the required trap seal depth for floor drains in occupied spaces?
a) 1″
b) 2″ – Rationale: Minimum 2″ but ≤4″; deeper seals prevent sewer gas but risk
siphoning.
c) 3″
d) 4″
, Q8. A plumbing apprentice must be directly supervised by a journeyman if the
work involves:
a) Unstopping a toilet
b) Altering a gas piping system – Rationale: Gas work and medical gas systems
require licensed supervision in all states (2026).
c) Changing a faucet washer
d) Adjusting a float valve
Q9. Which is a high-hazard cross-connection?
a) Garden hose submerged in a pesticide tank – Rationale: Backsiphonage of
toxic chemicals is high hazard (Class 4).
b) Laundry sink overflow
c) Roof drain to storm sewer
d) Condensate drain to lavatory
Q10. Minimum size of a residential water service line (2026 IRC):
a) 1/2″
b) 3/4″ – *Rationale: 2026 update – 3/4″ minimum for single-family due to higher
peak demand (fixture count increase).*
c) 1″
d) 1 1/4″
Q11. What is the maximum number of water closets permitted on a 3″ soil stack?
a) 2
b) 3 – Rationale: IPC allows 3 WC on 3″ stack with proper venting; 4″ stack
allows 6.
c) 4
d) 6
Q12. Which device prevents thermal expansion pressure in a closed plumbing
system?
a) Pressure reducing valve
b) Expansion tank – Rationale: Required when a check valve or PRV is present;
2026 codes increase tank sizing for tankless heaters.
c) Vacuum breaker
d) Air admittance valve
Q13. A plumbing contractor’s license bond is primarily intended to:
a) Protect the customer from financial loss – Rationale: Surety bond
compensates owner if contractor fails to complete or violates code.
CERTIFICATION EXAM (2026
Edition)|||| questions and answers
with rationales/graded A+/2026
update/100% correct /instant
download
Exam Code: EPX-2026
Total Questions: 80
Time Limit: 180 minutes
Passing Score: 75% (60 correct)
Instructions: Select the best answer for each question. Correct answers
are highlighted in bold with rationale provided.
SECTION 1: CODES, SAFETY, AND PROFESSIONAL PRACTICE (Q1–15)
Q1. According to the 2026 IPC, what is the maximum vertical distance allowed for
a fixture drain without venting?
a) 4 ft
b) 6 ft
c) 8 ft – Rationale: 2026 update maintains 8 ft for most fixtures to prevent trap
siphonage, except water closets (6 ft).
d) 10 ft
Q2. A plumbing permit is NOT required for:
a) Replacing a toilet flapper – Rationale: Minor repairs like flappers, washers, or
aerators are exempt; replacing the entire toilet requires a permit.
b) Installing a water heater
c) Adding a bathroom sink
d) Modifying a DWV branch line
,Q3. What is the minimum clearance in front of a commercial water heater for
service access (2026 IRC/IBC)?
a) 18″
b) 24″ – Rationale: 24″ working clearance is required for electrical panels and
water heater access; some jurisdictions raised to 30″ in 2026 for heat pump units.
c) 30″
d) 36″
Q4. Which material is NOW prohibited for domestic water supply lines in most US
jurisdictions (2026)?
a) PEX-A
b) CPVC
c) Lead-containing solder – *Rationale: “Lead-free” means ≤0.25% weighted
average; lead solder banned federally since 1986, but 2026 codes reinforce zero
tolerance.*
d) Brass fittings
Q5. A backflow prevention device is required on:
a) Hose bibb with chemical injector – Rationale: High hazard (chemicals)
requires RPZ; a standard hose bibb without chemicals needs only a vacuum
breaker.
b) Toilet supply line
c) Kitchen sink faucet
d) Washing machine box
Q6. The maximum fixture unit (DFU) load for a 4″ horizontal drainage pipe at 1/8″
per foot slope is:
a) 90 DFU
b) 180 DFU – *Rationale: 2026 tables unchanged; 4″ @ 1/8″ slope = 180 DFU;
1/4″ slope = 216 DFU.*
c) 216 DFU
d) 300 DFU
Q7. What is the required trap seal depth for floor drains in occupied spaces?
a) 1″
b) 2″ – Rationale: Minimum 2″ but ≤4″; deeper seals prevent sewer gas but risk
siphoning.
c) 3″
d) 4″
, Q8. A plumbing apprentice must be directly supervised by a journeyman if the
work involves:
a) Unstopping a toilet
b) Altering a gas piping system – Rationale: Gas work and medical gas systems
require licensed supervision in all states (2026).
c) Changing a faucet washer
d) Adjusting a float valve
Q9. Which is a high-hazard cross-connection?
a) Garden hose submerged in a pesticide tank – Rationale: Backsiphonage of
toxic chemicals is high hazard (Class 4).
b) Laundry sink overflow
c) Roof drain to storm sewer
d) Condensate drain to lavatory
Q10. Minimum size of a residential water service line (2026 IRC):
a) 1/2″
b) 3/4″ – *Rationale: 2026 update – 3/4″ minimum for single-family due to higher
peak demand (fixture count increase).*
c) 1″
d) 1 1/4″
Q11. What is the maximum number of water closets permitted on a 3″ soil stack?
a) 2
b) 3 – Rationale: IPC allows 3 WC on 3″ stack with proper venting; 4″ stack
allows 6.
c) 4
d) 6
Q12. Which device prevents thermal expansion pressure in a closed plumbing
system?
a) Pressure reducing valve
b) Expansion tank – Rationale: Required when a check valve or PRV is present;
2026 codes increase tank sizing for tankless heaters.
c) Vacuum breaker
d) Air admittance valve
Q13. A plumbing contractor’s license bond is primarily intended to:
a) Protect the customer from financial loss – Rationale: Surety bond
compensates owner if contractor fails to complete or violates code.
