Exam Cheat Sheet · Quick Reference
Idaho Plumbing Journeyman Exam
Idaho · PSI Services Contractor
Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
100
Passing score
70%
Exam time
180 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Idaho State Portion 100 questions
2015 Uniform Plumbing Code Chapter 3
6 Q · 6%
Material standards, listing requirements, and manufacturer marking of pipe, fittings, and componentsProhibited fittings and practices in drainage, vent, and waste piping systemsProtection of piping through walls, floors, and structural members including sleeves and nail platesHangers, supports, and pipe support intervals by material typeTrenching, excavation, backfill, and thermoplastic pipe bedding requirementsAlternate materials, alternative engineered design approval process, and equivalency testingFlood hazard area and coastal high hazard area plumbing installation requirementsTest gauge pressure ranges and incrementation requirements for pressure testing
2015 Uniform Plumbing Code Chapter 4
8 Q · 8%
Fixture installation requirements (clearances, spacing, and securing methods)Minimum number of required plumbing fixtures by occupancy type (Table 422.1)Water consumption limits and flow rates for fixtures (lavatories, showers, water closets, urinals, sinks)Shower compartment construction, lining materials, and waterproofing requirementsFixture-specific standards (water closets, urinals, lavatories, bathtubs, bidets, dishwashers, floor drains)Flushing devices (flushometer valves, flush tanks, and antisiphon requirements)Hot water temperature limitations for lavatories, bathtubs, and bidetsProhibited fixtures and special/alternative fixture requirements
2015 Uniform Plumbing Code Chapter 5
4 Q · 4%
Water heater location requirements and prohibited installationsTemperature, pressure, and relief valve requirementsCombustion air supply methods and sizing calculationsVenting system types and selection for Category I appliancesVent and chimney termination requirementsVent connector materials, sizing, clearances, and installationWater heater support, seismic strapping, and drainage pan requirementsSizing of Category I venting systems using tables and engineering methods
2015 Uniform Plumbing Code Chapter 6
8 Q · 8%
Backflow prevention devices, assemblies, and methods (types, components, and applicable standards)Cross-connection control and prohibited unlawful connectionsWater supply pipe materials, approved standards, and lead content requirementsPipe and tubing joining methods by material type (copper, CPVC, PEX, PE, PP, etc.)Water pressure regulation, pressure relief valves, and expansion tanksSizing water supply and distribution systems using fixture units and Table 610.4Identification and labeling of potable and nonpotable water systemsResidential fire sprinkler system installation, design, and pipe sizing
2015 Uniform Plumbing Code Chapter 7
9 Q · 9%
Drainage pipe materials, standards, and installation restrictions by location (above/belowground)Drainage fixture unit (DFU) values and sizing of drainage pipingJoints and connections for drainage piping by material typeCleanout requirements: location, spacing, clearance, and accessGrade and slope requirements for horizontal drainage piping and building sewersDrainage of fixtures below main sewer level: backwater valves, ejectors, sumps, and alarmsBuilding sewer materials, sizing, installation, separation from water pipes, and testingChanges in direction of drainage flow using approved fittings
2015 Uniform Plumbing Code Chapter 8
4 Q · 4%
Air gap and air break requirements for indirect waste pipingIndirect waste piping for food and beverage handling establishmentsIndirect waste receptor requirements and installation restrictionsCondensate waste disposal, pipe sizing, and overflow protectionChemical and industrial waste pretreatment and approved piping materialsSteam and hot water drainage condensers and sumpsPressure drainage connections and water softener discharge requirementsClear water wastes, swimming pool drainage, and cooling water connections
2015 Uniform Plumbing Code Chapter 9
9 Q · 9%
Vent pipe sizing based on fixture units and developed lengthVent termination requirements including roof and sidewall clearancesVent pipe grades, connections, and rise above flood-level rimWet venting requirements for vertical and horizontal bathroom groupsCircuit venting requirements and limitationsSpecial venting for island fixtures and air admittance valve restrictionsCombination waste and vent system requirements and limitationsVent stack and relief vent requirements for multi-story drainage stacks
2015 Uniform Plumbing Code Chapter 10
5 Q · 5%
Trap installation requirements and fixture trap rulesTrap arm lengths and Table 1002.2 distance requirementsProhibited trap types and trap seal depth requirementsGrease interceptor types, sizing, and installation requirementsHydromechanical vs. gravity grease interceptor sizing methodsSand interceptor construction, sizing, and design requirementsOil and flammable liquid interceptor requirements and ventingFloor drain trap seals and trap seal primer requirements
2015 Uniform Plumbing Code Chapter 11
10 Q · 10%
Storm water drainage system materials and approved pipe typesSizing of roof drains, vertical conductors, and leaders using Table 1101.12Sizing of horizontal storm drains and sewers using Table 1101.8Primary and secondary (emergency) roof drainage requirementsSubsoil drain installation, sump requirements, and discharge optionsControlled-flow roof drainage system requirements and conditionsTraps on storm drains and leaders connected to combined sewersTesting methods for storm drainage systems (water test and air test)
2015 Uniform Plumbing Code Chapter 12
12 Q · 12%
Gas piping system design, sizing methods, and allowable pressure dropAcceptable piping materials, joining methods, and fittings (metallic and plastic)Underground and aboveground gas piping installation requirementsPressure testing, leak detection, and purging proceduresInspection requirements, certificates of inspection, and authority to disconnectGas meters, pressure regulators, and shutoff valvesAppliance connections, connectors, sediment traps, and shutoff valvesElectrical bonding and grounding of gas piping systems
2017 Idaho State Plumbing
25 Q · 25%
Testing and inspection of plumbing systems under Idaho's amended Section 105.3 (tests in the presence of the AHJ; exhibition and minor-work exceptions)Idaho definition of 'plumbing system' incorporated from Section 54-2604, Idaho Code (Section 218)Fixture amendments: qualities of fixtures (401.2), shower receptor floor slope 1/8 to 1/2 inch per foot (408.5), deleted Sections 403.3, 408.7.5 and 409.4Water heater amendments: Table 501.1(1) deleted, Category 3/4 vent air test at 5 psi for 15 minutes (503.1), seismic provisions deleted (507.2), 18-inch ignition-source height in garages (507.13)Backflow amendments: Table 603.2 changes, hose outlets and self-draining frost-proof hose bibbs (603.5.7), carbonated beverage dispensers (603.5.12), chemical dispensers (603.5.21)Water supply amendments: tracer wire exception (604.10.1), PE water service joints inside buildings (605.6.2), 42-inch cover for yard piping (609.1), plastic pipe testing (609.4), water hammer and pipe insulation (609.10, 609.11)Fixture unit and softener amendments: two fixture units for bathtubs and clothes washers (Tables 610.3, 702.1, 703.2), pre-plumbed softener loop in new residences (610.2), softener sizing footnote (611.4)Drainage amendments: 2-inch minimum underground drain and vent (703.1), double sanitary tees (704.2), one-step solvent cement (705.5.2), cleanout locations and 50-foot intervals (707.4), ejector and sump exceptions (710.3, 710.5), air testing of plastic DWV (712.1, 723.0), 4-inch building sewer (717.1)Indirect waste amendments: food-handling fixture air gaps and 1-inch minimum piping (801.3.3), water softener drain 3/4 inch to an approved location (805.4), domestic dishwasher high loop without an air gap (807.3)Venting, trap and gray water amendments: sidewall venting (906.1), horizontal wet vent (908.1), air admittance valve limits (909.0), trap arm 180-degree rule (1002.3), trap seal primers (1007.1), garage floor drain interceptors (1016.1), gray water inspection and IDEQ jurisdiction (1502.1)
Key Distinctions
AccessiblevsReadily Accessible
'Accessible' may require removal of an access panel or similar obstruction to reach, while 'Readily Accessible' allows direct access without removing any panel, door, or obstruction.
2017 ISPC, Section 203.0Clearing Stoppages / Repairing Leaks (no replacement)vsReplacing Defective Pipe with New Material
Clearing stoppages and repairing leaks without replacing or rearranging valves, pipes, or fixtures is permit-exempt; removing and replacing defective pipe with new material is classified as new work and requires a permit and inspection.
2017 ISPC Section 104.2Permit Application Expiration (no permit issued)vsIssued Permit Expiration (work not commenced)
A permit application expires after 180 days if no permit is issued; an already-issued permit expires and becomes null and void if authorized work is not commenced within 180 days of the permit date.
2017 ISPC Section 104.3.3Plumbing CodevsMechanical Code
When the plumbing code and mechanical code conflict, the plumbing code prevails.
2017 ISPC Section 102.1General RequirementvsSpecific Requirement
Where a general requirement and a specific requirement conflict in the 2017 ISPC, the specific requirement prevails.
2017 ISPC, Section 102.1Hose Bibb on Reclaimed Water (public area)vsQuick-Disconnect Device on Reclaimed Water (public area)
Hose bibbs are prohibited on reclaimed water piping in areas accessible to the public; access must instead be provided through a quick-disconnect device that differs from those on the potable water system.
2017 ISPC Section 1503.9Potable Water Makeup Supply (non-pressurized tank)vsReclaimed Water Makeup Supply (non-pressurized tank)
Potable water used as makeup water for a non-pressurized storage tank must be protected by an air gap; reclaimed water systems may also allow a reduced-pressure principle backflow preventer in addition to an air gap.
2017 ISPC Section 1504.4Underground InspectionvsRough-In Inspection
Underground inspection occurs before underground plumbing is covered, while rough-in inspection must be made prior to the installation of wall or ceiling membranes; both are among the three required AHJ inspections (underground, rough-in, final).
2017 ISPC, Section 105.2Work Commenced Without Permit (investigation fee)vsNormal Permit Fee
When work is started before a permit is obtained, a special investigation is required and an investigation fee equal to the permit fee is collected in addition to the normal permit fee.
2017 ISPC, Sections 104.5.1 and 104.5.2Moved/Relocated Building PlumbingvsOriginal In-Place Building Plumbing
Plumbing in a building moved from one location to another must comply with provisions for new installations and be completely tested as prescribed for new work, unlike existing in-place plumbing that may remain if code-compliant.
2017 ISPC, Section 102.7Flush-Valve Water Closet DFU RatingvsLavatory / Floor Drain / Service Sink DFU Rating
Per UPC Table 702.1, flush-valve water closets are rated at 6 DFU each, while lavatories are 1 DFU, floor drains are 2 DFU, and service sinks are 3 DFU each.
UPC Chapter 7, Table 702.1 (Drainage Fixture Unit Values)Stop Work OrdervsNormal Work Authorization
When the AHJ issues a stop work order for work contrary to code provisions, all work must cease immediately and may not resume until the AHJ authorizes continuation; normal work authorization allows work to proceed once a permit is issued.
2017 ISPC, Section 106.4Key Terms
Primary Purpose of the 2017 ISPC (Section 101.3) 2017 ISPC Section 101.3
The 2017 Idaho State Plumbing Code is an ordinance providing minimum requirements and standards for the protection of the public health, safety, and welfare.
Plumbing Code Prevails Over Mechanical Code (Section 102.1) 2017 ISPC, Section 102.1
Per 2017 ISPC Section 102.1, where plumbing code requirements conflict with mechanical code requirements, the plumbing code shall prevail; where a general and specific requirement conflict, the specific requirement prevails.
Permit Application Expiration (Section 104.3.3) 2017 ISPC Section 104.3.3
Per 2017 ISPC Section 104.3.3, a permit application for which no permit is issued shall expire by limitation after 180 days following the date of application.
Permit Expiration – Work Not Commenced (Section 104.4.3) 2017 ISPC, Section 104.4.3
Per 2017 ISPC Section 104.4.3, an issued permit expires and becomes null and void if authorized work is not commenced within 180 days; a new permit at one-half the fee may be obtained if no changes were made and suspension has not exceeded one year.
Permit Exemptions (Section 104.2) 2017 ISPC Section 104.2
Per 2017 ISPC Section 104.2, no permit is required for clearing stoppages (including water closet removal/reinstallation) or repairing leaks, provided no replacement or rearrangement of valves, pipes, or fixtures is involved.
Defective Pipe Replacement = New Work (Section 104.2(1)) 2017 ISPC Section 104.2
Per 2017 ISPC Section 104.2(1), when a trap, drain pipe, soil, waste, or vent pipe becomes defective and must be removed and replaced with new material, it is considered new work requiring a permit and inspection.
Cover / Concealment Prohibition Before Inspection (Sections 105.1 & 105.2) 2017 ISPC, Sections 105.1 and 105.2.1.2
Per 2017 ISPC Sections 105.1 and 105.2, no plumbing system or portion thereof shall be covered, concealed, or put into use until it has been tested, inspected, and approved; a rough-in inspection must be made before wall or ceiling membranes are installed.
Board of Appeals Limitations (Section 107.2) 2017 ISPC Section 107.2
Per 2017 ISPC Section 107.2, the Board of Appeals has no authority to interpret administrative provisions of the code and is not empowered to waive any code requirements.
Each Day a Violation Continues = Separate Offense (Section 106.3) 2017 ISPC Section 106.3
Per 2017 ISPC Section 106.3, each separate day or portion thereof during which a violation of the code occurs or continues shall be deemed to constitute a separate offense.
Stop Work Order (Section 106.4) 2017 ISPC, Section 106.4
Per 2017 ISPC Section 106.4, where work is being done contrary to code provisions the AHJ may order work stopped, and persons so ordered must immediately cease work until authorized to proceed.
Inspection Notice Requirement (Section 105.2.4) 2017 ISPC, Section 105.2.4
Per 2017 ISPC Section 105.2.4, the permit holder must notify the AHJ that work is ready for inspection not less than 24 hours before the work is to be inspected.
Reinspection Fee (Section 105.2.6) 2017 ISPC, Section 105.2.6
Per 2017 ISPC Section 105.2.6, a reinspection fee may be assessed when work is not complete, corrections have not been made, approved plans are not available, access is not provided, or plans were deviated from without approval.
Drainage Fixture Unit (DFU) UPC Chapter 7, Table 702.1 (Drainage Fixture Unit Values)
A DFU is a unit of measure used to estimate the load-producing effect of different plumbing fixtures on the sanitary drainage system; per UPC Table 702.1, flush-valve water closets = 6 DFU, lavatories = 1 DFU, floor drains = 2 DFU, service sinks = 3 DFU.
Reclaimed (Recycled) Water – Hose Bibb Prohibition (Section 1503.9) 2017 ISPC Section 1503.9
Per 2017 ISPC Section 1503.9, hose bibbs shall not be installed on reclaimed water piping in areas accessible to the public; public access must be through a quick-disconnect device that differs from potable system devices.
Air Gap – Potable Makeup Water for Non-Pressurized Tank (Section 1504.4) 2017 ISPC Section 1504.4
Per 2017 ISPC Section 1504.4, potable or reclaimed water may be used as makeup water for a non-pressurized storage tank only if the supply is protected by an air gap in accordance with the code.
Riser Diagram Required Contents (UPC Section 301.5.3) UPC Section 301.5.3
Per UPC Section 301.5.3, design documents must include floor plans and a riser diagram indicating, where appropriate, the direction of flow, pipe sizes, grade of horizontal piping, loading, and location of fixtures and appliances.
Formulas to Know
Total Drainage Fixture Units (DFU) on a Stack
Total DFU = Σ (fixture count × DFU rating per fixture type) for all floors; e.g., flush-valve WC × 6 + lavatory × 1 + floor drain × 2 + service sink × 3