10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The CO-RP exam has 100 questions and runs 4 hours.
These 10 free CO-RP questions are organized by exam domain, so you can see how each part of the Colorado Residential Plumber License Exam blueprint is tested. Reveal the answer and explanation under each question.
A residential irrigation system injects a treatment chemical classified as a health hazard. A booster pump can raise irrigation-side pressure above the potable supply pressure, and the connection remains pressurized between watering cycles. Which backflow assembly is suitable for these conditions?
Correct answer: A - An ASSE 1013 reduced-pressure-principle assembly.
Two parallel horizontal pipe runs differ by 9 inches laterally and 12 inches in elevation, measured between centerlines. They will be joined by a rolling offset using two 45-degree elbows. Each elbow's specified takeout along the diagonal pipe is 1.50 inches. What length of straight pipe should be cut between the elbows, to the nearest hundredth of an inch?
Correct answer: B - 18.21 inches.
A PEX water line passes through a wood stud with the pipe's nearest surface 1 inch from the stud face that will receive drywall. The installer has already applied 0.025-inch plastic sheathing to prevent rubbing. Before the wall is closed, which added protection satisfies the 2021 IPC requirement against nails and screws?
Correct answer: B - A 0.060-inch-thick steel shield plate covering the vulnerable area of the stud face.
A built-in domestic dishwasher drains into the disposer inlet upstream of the kitchen sink's trap. Its hose is securely fastened to the underside of the countertop before descending to the disposer. The manufacturer permits this arrangement, and no local amendment requires a countertop air-gap fitting. Applying the 2021 IPC, how should the connection be assessed?
Correct answer: D - Accept it; the permitted disposer connection and secured high loop meet the stated waste-connection requirements.
While a plumber is investigating a gas-fired water heater's venting, the home's carbon monoxide alarm sounds. An occupant reports a headache and nausea, although nobody smells gas. What takes priority over completing the service diagnosis?
Correct answer: D - Leave the building with the occupants and call 911 from outside.
A proposed 3-inch horizontal fixture branch carries 24 drainage fixture units (DFU) into a 3-inch building drain pitched at 1/4 inch per foot. The building sewer beyond it is 4 inches. The 2021 IPC permits 20 DFU on the 3-inch horizontal fixture branch, 160 DFU on a 4-inch branch, and 42 DFU on the 3-inch building drain at that slope. Select the revision that satisfies both loading and downstream pipe-size requirements.
Correct answer: A - Increase both the horizontal fixture branch and the building drain to 4 inches.
For a new house, the basement finished floor is at elevation 98.0 feet and the main floor is at 108.0 feet. The cover of the next upstream public-sewer manhole is at 102.0 feet. Both floors can discharge by gravity. Under the 2021 IPC, how should protection against sewer backup be arranged?
Correct answer: A - Protect the basement branch with a backwater valve; connect main-floor drainage downstream of it.
A homeowner reports weak flow whenever several fixtures run. Accurate gauges immediately before and after the whole-house sediment filter are at the same elevation. Both read 62 psi with no flow. With three fixtures running, the inlet gauge reads 60 psi and the outlet gauge reads 28 psi. The filter's isolation valves are fully open. Where should diagnostic work begin?
Correct answer: C - Inspect the filter element for a restriction that appears under flow.
A Colorado remodel will add one fixture near an existing, code-compliant horizontal wet vent serving a bathroom group. Each proposed fixture is on the same floor. With any one addition, the total load would remain below the equivalent load of two bathroom groups, and the pipe sizing and connection geometry would comply. Under Colorado's exception to the 2021 IPC horizontal wet-vent rule, which fixture may join the wet-vented portion?
Correct answer: C - A non-bathroom handwashing lavatory rated at 1 DFU.
Sewer odor returns at a seldom-used floor drain in a vacation home several weeks after its trap is refilled. The 3-inch-deep trap seal holds during leakage testing, and nearby fixture discharges do not change its level. Water disappears gradually during long periods without use. Which correction addresses the identified failure mechanism?
Correct answer: B - Retain the trap and install a listed barrier-type trap-seal protection device.
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