Master / Journeyman Plumber Exam
Storm Drainage Practice Questions
25 practice questions with detailed explanations — aligned to the Master / Journeyman Plumber Exam.
Q1.Roof drains shall have domed strainers that extend not less than ___ inches above the surface of the roof.
A.2B.3C.4D.6C. 4Explanation: IPC 1105.1 requires roof drain strainers to extend at least 4 inches above the roof surface to prevent debris blockage.
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Q2.Secondary (emergency) roof drains or scuppers are required:
A.Only in hurricane zonesB.Where the roof perimeter construction extends above the roof in such a manner that water will be entrapped (parapet walls)C.On all roofs regardless of designD.Only for flat roofs over 5,000 sq ftB. Where the roof perimeter construction extends above the roof in such a manner that water will be entrapped (parapet walls)Explanation: IPC 1101.7 requires secondary drainage where water can be trapped if the primary drains clog, preventing roof collapse.
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Q3.The size of vertical conductors and leaders is based on:
A.The diameter of the drainB.The height of the buildingC.The maximum projected roof area and the rainfall rateD.The number of windowsC. The maximum projected roof area and the rainfall rateExplanation: IPC 1106.1 sizes storm piping based on the square footage of the roof area served and the local 100-year hourly rainfall rate.
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Q4.A 'Leader' is defined as:
A.An interior vertical drainage pipeB.An exterior drainage pipe for conveying storm water from roof or gutter drainsC.The main storm sewerD.A horizontal pipeB. An exterior drainage pipe for conveying storm water from roof or gutter drainsExplanation: IPC Definitions differentiate between a 'Conductor' (inside the building) and a 'Leader' (outside/exterior downspout).
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Q5.Storm water shall NOT be drained into:
A.A storm sewerB.A combined sewer (where permitted)C.Sewers intended for sewage only (sanitary sewers)D.A dedicated drywellC. Sewers intended for sewage only (sanitary sewers)Explanation: IPC 1101.2 prohibits connecting storm water (rain) to sanitary sewers intended only for sewage, as it overloads the treatment plant.
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Q6.Secondary roof drain systems shall discharge:
A.Into the primary storm drainB.To the sanitary sewerC.Separately from the primary system to a visible location (above grade)D.Into a sump pumpC. Separately from the primary system to a visible location (above grade)Explanation: IPC 1101.7 requires secondary drains to discharge separately and visibly so building occupants become aware that the primary system is blocked.
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Q7.The area of the roof strainers (inlet area) must be at least ___ times the area of the conductor or leader to which it connects.
A.1B.1.5C.2D.3B. 1.5Explanation: IPC 1105.1 states the inlet area above the roof must be not less than 1.5 times the area of the pipe inlet.
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Q8.Subsoil drains (French drains) shall be piped to:
A.The sanitary sewerB.A storm drain, an approved watercourse, or a sumpC.The street curb directlyD.The water meter pitB. A storm drain, an approved watercourse, or a sumpExplanation: IPC 1113.1 requires subsoil drains to discharge to an approved location like a storm sewer or sump; never the sanitary sewer unless specifically approved.
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Q9.Scuppers used for secondary roof drainage shall have an opening dimension of not less than:
A.2 inchesB.3 inchesC.4 inchesD.6 inchesC. 4 inchesExplanation: IPC 1101.7 requires scupper openings to be at least 4 inches high.
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Q10.Sizing of storm drains is based on the rainfall rate of a storm of ___ duration and ___ return period.
A.1 hour, 10 yearB.1 hour, 100 yearC.24 hour, 50 yearD.15 minutes, 100 yearB. 1 hour, 100 yearExplanation: IPC 1106.1 bases calculations on the 100-year hourly rainfall rate.
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Q11.Controlled flow roof drain systems are permitted when:
A.The roof structure is designed for the maximum retention water weightB.The pipes are too smallC.It is a residential houseD.The owner wants to save moneyA. The roof structure is designed for the maximum retention water weightExplanation: IPC 1110.1 allows controlled flow (slow drainage) only if the roof can structurally support the accumulated water load during a storm.
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Q12.When calculating roof area for storm drain sizing, vertical walls that drain onto the roof must be calculated as:
A.Zero areaB.50% of the wall area added to the roof areaC.100% of the wall area addedD.Only if they have windowsB. 50% of the wall area added to the roof areaExplanation: IPC 1106.4 requires 50% of the area of any vertical wall that diverts water to the roof to be added to the projected roof area calculation.
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Q13.Which material is acceptable for inside storm conductor piping?
A.PVC (Schedule 40)B.Cast IronC.ABSD.All of the aboveD. All of the aboveExplanation: IPC Table 1102.4 lists PVC, ABS, Cast Iron, Copper, and others as approved materials for building storm sewers and conductors.
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Q14.Are cleanouts required on storm drain systems?
A.No, neverB.Yes, the same as sanitary systems (every 100 feet, change of direction)C.Only at the base of stacksD.Only on the roofB. Yes, the same as sanitary systems (every 100 feet, change of direction)Explanation: IPC 1104.1 requires cleanouts on storm drainage systems essentially following the same rules as sanitary drainage (708).
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Q15.Backwater valves are required in storm drainage systems when:
A.The roof is flatB.The storm sewer is combined with sanitaryC.Piping is subject to backflow from the public sewer systemD.Always requiredC. Piping is subject to backflow from the public sewer systemExplanation: IPC 1101.9 requires backwater valves where the system is subject to backflow/surcharge from the public sewer.
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Q16.A flat roof has a total area of 4,000 sq ft. The rainfall rate is 3 inches/hour. What is the equivalent GPM load?
A.100 GPMB.125 GPMC.200 GPMD.400 GPMB. 125 GPMExplanation: Formula: GPM = (Area x Rainfall) / 96. (4000 x 3) / 96 = 12000 / 96 = 125 GPM.
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Q17.Secondary roof drains must discharge at a point:
A.Below the primary drainB.Above grade and visible to building occupantsC.Into the sanitary sewerD.Into a drywellB. Above grade and visible to building occupantsExplanation: The discharge must be visible so maintenance personnel know a blockage exists in the primary system.
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Q18.When connecting a subsoil drain to a storm drain, it must connect through:
A.A backwater valveB.A cleanoutC.An open sumpD.A wye fitting onlyA. A backwater valveExplanation: IPC 1113.1.3: Subsoil drains connecting to a storm sewer shall be protected by a backwater valve to prevent the sewer from flooding the foundation.
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Q19.The minimum size of a subsoil drain pipe is:
A.2 inchesB.3 inchesC.4 inchesD.6 inchesC. 4 inchesExplanation: IPC 1111.1 requires subsoil drains (foundation drains) to be not less than 4 inches in diameter.
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Q20.Are traps required on storm drains?
A.Yes, alwaysB.No, traps are prohibitedC.Traps are required only if the drain connects to a combined sewer or where sewer gas could escapeD.Only on roof drainsC. Traps are required only if the drain connects to a combined sewer or where sewer gas could escapeExplanation: IPC 1103.1 states storm drains do not require traps unless they connect to a combined sewer (carrying sanitary waste) or where necessary to prevent sewer gas escape.
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Q21.Roof drains must be spaced not more than ___ feet apart?
A.20B.50C.100D.There is no specific spacing requirement in the IPC, sizing is based on areaD. There is no specific spacing requirement in the IPC, sizing is based on areaExplanation: The IPC dictates sizing based on area and flow, not arbitrary spacing distances. Placement depends on roof slope and structural design.
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Q22.Vertical conductors and leaders shall be sized based on:
A.IPC Table 1106.2(1)B.The size of the gutterC.The height of the buildingD.Always 4 inchesA. IPC Table 1106.2(1)Explanation: Sizing is strictly tabular based on the max roof area and rainfall rate (Table 1106.2(1)).
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Q23.Which material is prohibited for underground storm building sewers?
A.ABS PlasticB.Cast IronC.AluminumD.PVCC. AluminumExplanation: Aluminum piping is prohibited in soils due to rapid corrosion.
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Q24.The sizing of gutters (semicircular) is based on:
A.Slope, Roof Area, and Rainfall RateB.Depth onlyC.Length onlyD.ColorA. Slope, Roof Area, and Rainfall RateExplanation: IPC Table 1106.6 requires knowing the slope, the roof area being drained, and the rainfall rate to select the diameter.
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Q25.When a combined sewer system is used, the building storm drain and building sanitary drain must:
A.Combine inside the buildingB.Combine outside the building (at the property line or building sewer)C.Never combineD.Use an AAVB. Combine outside the building (at the property line or building sewer)Explanation: Typically, storm and sanitary building drains remain separate inside the building and combine only at the building sewer or public sewer connection point to prevent sewer gas backup into storm drains inside.
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