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Sanitary Drainage — ICC P1 Practice Questions

28 questions · 23% of the ICC P1 exam

Worked questions

1. A testable double-check backflow-preventer assembly serves a house. Apart from the tests required at installation and immediately after repairs or relocation, what recurring testing interval does 2024 IRC P2503.8.2 require?

  • AEvery 6 months
  • Every 12 months
  • CEvery 18 months
  • DEvery 24 months

Where to look it up

https://dos.ny.gov/nys-residential-code-noa-7242025

Why B is correct

The specified testable assembly must be tested every year, in addition to testing at installation and immediately after repairs or relocation. This is a code requirement, not merely a recommendation. Do not confuse a testable double-check assembly with a different non-testable dual-check device. Source: 2024 IRC P2503.8.1 and P2503.8.2, reproduced without a substantive state modifier in the official 2025 RCNYS (2024 IRC base). https://dos.ny.gov/nys-residential-code-noa-7242025

2. Under 2024 IRC P3005.3 (May 2024 printing), what is the minimum uniform slope for a 3-inch horizontal sanitary drainage pipe?

  • A1/4 inch per foot
  • 1/8 inch per foot
  • C1/2 inch per foot
  • D3/16 inch per foot

Where to look it up

https://codes.iccsafe.org/content/IRC2024P2/chapter-30-sanitary-drainage

Why B is correct

P3005.3 requires at least 1/8 inch per foot for horizontal drainage piping 3 inches or larger. The smaller-diameter category, 2-1/2 inches or less, requires at least 1/4 inch per foot. The specified diameter selects the answer. These are drainage-pipe limits; they are not a single combined waste-and-vent rule. Source: https://codes.iccsafe.org/content/IRC2024P2/chapter-30-sanitary-drainage

3. Under 2024 IRC P3005.3 (May 2024 printing), what is the minimum uniform slope for a 2-inch horizontal sanitary drainage pipe?

  • 1/4 inch per foot
  • B1/8 inch per foot
  • C1/2 inch per foot
  • D3/8 inch per foot

Where to look it up

https://codes.iccsafe.org/content/IRC2024P2/chapter-30-sanitary-drainage

Why A is correct

P3005.3 puts 2-inch horizontal drainage pipe in the 2-1/2-inch-and-smaller category, which requires at least 1/4 inch per foot. The 1/8-inch-per-foot limit belongs to pipe 3 inches or larger. Larger slopes among the choices are above the stated minimum; they are not the minimum asked for. P2803 is not the sanitary drainage slope provision. Source: https://codes.iccsafe.org/content/IRC2024P2/chapter-30-sanitary-drainage

4. An inspector reviews proposed plastic pipe for an above-ground residential DWV vent stack serving a water closet. No alternative material approval is involved. Which proposed product explicitly matches a material and standard in 2024 IRC Table P3002.1(1)?

  • Schedule 40 PVC DWV pipe complying with ASTM D2665
  • BPVC pressure pipe complying only with ASTM D1785 and not identified for DWV service
  • CCPVC potable-water pipe complying only with ASTM D2846 and not identified for DWV service
  • DPEX water-distribution tubing complying only with ASTM F876

Where to look it up

https://dos.ny.gov/nys-residential-code-noa-7242025

Why A is correct

The table includes Schedule 40 PVC DWV pipe and ASTM D2665. A pressure-water or hot-and-cold-water standard alone does not establish approval for this DWV vent use. PVC is one permitted choice, not the only material allowed for every water-closet vent stack. Source: 2024 IRC P3002.1 and Table P3002.1(1), reproduced without a substantive state modifier in the official 2025 RCNYS (2024 IRC base). https://dos.ny.gov/nys-residential-code-noa-7242025

24 more in the bank

Answers and explanations for these are in the app.

  • A plumber is designing a waste and vent system for a residential building. Which of the following is the correct venting distance from a fixture to the vent stack?
  • A plumber is installing a backflow preventer. Which of the following is the correct location for the backflow preventer?
  • A plumber is installing a waste and vent system for a kitchen sink. Which of the following is the minimum required venting height above the highest fixture trap?
  • A plumber is repairing a drain line. Which tool is most effective for cleaning a drain line?
  • A plumber is replacing the drainage piping in a bathroom. Which slope is required for the drain piping in a bathroom?
  • A property owner has reported low water pressure in their home. Which of the following is the most likely cause of this issue?
  • A residential property has a crawl space with a concrete floor. During the inspection, you notice that the drain pipes are located directly under the floor joists. What is the minimum clearance required between the bottom of the drain pipe and the top of the floor joist?
  • A residential property has a crawl space with a vent stack that extends above the roof. The vent stack is made of Schedule 40 PVC. According to the 2024 International Residential Code, what is the minimum height above the roof that the vent stack must be installed?
  • A residential property has a drainage system that includes a combination of cast iron and PVC piping. According to the 2024 International Residential Code, what is the maximum distance between cleanouts in a drainage system?
  • A vent stack for a lavatory is required to be a minimum of what size?
  • During an inspection of a residential property, you find that the water heater is located in an unventilated attic. What action should you take according to the 2024 International Residential Code?
  • In a residential setting, what is the minimum backflow prevention assembly required for a fire sprinkler system?
  • What is the maximum allowable temperature for the hot water discharge from a water heater?
  • What is the maximum distance a waste pipe can be from the vent stack in a residential building?
  • What is the maximum distance from the water heater to the vent termination in a residential setting?
  • What is the minimum required venting for a water heater in a residential property?
  • When is it necessary to install a backflow preventer on a water supply line?
  • When replacing an existing water heater, what is the minimum clearance required between the water heater and combustible materials?
  • Which of the following is not a requirement for the installation of a backwater valve in a residential property?
  • Which of the following is not a valid reason for a plumbing inspection in a residential property?
  • Which of the following is the correct venting method for a clothes washer in a residential building?
  • Which type of pipe is commonly used for the main waste and vent stack in a residential building, and what is the maximum length it can be?
  • Which type of pipe is typically used for the main drain from a building to the public sewer?
  • While inspecting an existing property, you come across a plumbing vent pipe that is discharging into a vertical stack vent. The vent pipe is located above the roof but is not visible from the ground. What is the minimum required height above the roof for a vent pipe to be considered accessible for inspection?

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