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Safety Cue
Task-specific safety guidance for ordinary work hazards.
Project 02
Identify Residential Water Supply and Drain Systems
Trace and document the visible hot- and cold-water supply piping and the drain-waste-vent piping serving a selected bathroom, kitchen, or utility area, and produce a verified system-layout record that later chapters will rely on before any pipe is cut or joined.
Field Cue System
These cues appear at the point of work. They identify safety, code, manufacturer, and measurement issues before they become water damage, injury, or failed inspections.
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Critical Safety Cue
Serious injury, scalding, electrical shock, or major property damage is possible.
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Field Safety Cue
Practical work-area safety: lighting, footing, ventilation, and housekeeping.
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Code Alert
Local requirements vary. Verify permit, inspection, and jurisdictional rules.
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Manufacturer Cue
Follow product-specific instructions for valves, tools, and equipment.
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Measurement Cue
Reference-point, clearance, and verification guidance.
Job Overview
This project qualifies you to trace and document the visible residential water-supply and drain-waste-vent (DWV) systems serving a selected bathroom, kitchen, or utility area. The finished work product is one completed System-Layout Record: a sketch showing every traced fixture-to-branch relationship, a table of accessible pipe markings, sizes, materials, and valve types, a list of unresolved or concealed piping, and a proceed or stop-work decision for any project that depends on the mapped system.
You will locate the building water entry, main shutoff, and water heater; identify hot and cold distribution piping by material, size, and direction; trace fixture supply branches without opening concealed walls; identify drain, waste, and vent piping by material, orientation, and termination; distinguish sanitary drainage from other piping systems; and record every observation, discrepancy, and unresolved condition on the System-Layout Worksheet.
This project builds directly on Project 01. The work area you isolated, drained, and protected there is the same area you will now map. Every later chapter — PEX and copper installation, DWV assembly, fixture replacement, appliance connections, and the Chapter 20 capstone — depends on knowing exactly which pipe is which before it is cut, joined, or disturbed.
Skills You Will Demonstrate
- PL-007 — Identify hot and cold water-supply lines by material, size marking, direction, and connected fixture.
- PL-008 — Identify visible drain, waste, and vent (DWV) piping by material, fitting orientation, and direction of flow.
- PL-009 — Trace fixture supply branches from the fixture back to the identifiable source without opening concealed walls.
- PL-010 — Identify vent piping and distinguish it from supply and drain piping by location, orientation, and termination.
- PL-011 — Identify shutoffs, cleanouts, and valve types serving the mapped area.
- PL-012 — Document the system layout in a verified, labeled record distinguishing verified, inferred, concealed, and unresolved piping.
Where This Skill Fits
Every later project in this book depends on correctly identifying which piping is supply, which is drain, and which is vent before any work begins. Chapters 4 through 7 install and replace supply piping; Chapters 8 and 9 install DWV piping and traps; Chapters 10 through 18 connect fixtures and appliances to existing systems. A misidentified pipe — mistaking a vent for a drain, or a cold branch for a hot branch — is a direct path to a cross-connection, a failed test, or a disturbed system that was never meant to be opened.
The system-mapping discipline built here — recording verified, inferred, concealed, and unresolved piping separately, rather than guessing at a single answer — is the same documentation standard used for concealed-work records throughout the book, including the rough-in inspection record required in the Chapter 20 capstone.
Scope and Intended Use
This project covers:
- locating the building water entry, meter where accessible, main shutoff, pressure-control equipment, treatment equipment, and water heater
- identifying visible hot- and cold-water distribution piping by material, size marking, direction, and connected fixtures
- locating fixture stops, branch valves, appliance valves, hose connections, and drain-down points
- tracing each selected fixture supply branch using only accessible, non-destructive observation
- identifying visible drain, waste, and vent piping by material, fitting orientation, direction of flow, cleanouts, traps, and vent termination
- distinguishing sanitary drainage from storm drainage, condensate, sump, irrigation, fuel-gas, hydronic, and other systems
- recording a verified system-layout record identifying verified, inferred, concealed, and unresolved portions
This project does not authorize the learner to:
- open a concealed wall, ceiling, or floor cavity to trace piping — trace only what is visible and accessible without demolition
- disconnect, cut, join, or replace any pipe, fitting, fixture, or appliance connection — that work is covered in later chapters
- assign a guessed function to any unidentified or conflicting piping — mark it unresolved instead
- proceed with any project that depends on the mapped system when the map contains an unresolved condition that affects that project's scope
Any piping condition that cannot be confidently identified using approved non-destructive methods must be marked unresolved and escalated to a qualified professional before a dependent project proceeds.
Reference Conventions
Establish these references before any tracing begins, and use them consistently across the sketch and worksheet.
| Term | Definition |
|---|---|
| Controlled area | The bathroom, kitchen, or utility area selected for mapping in this project |
| Verified piping | Piping whose material, size, direction, and connected fixture have been directly observed |
| Inferred piping | Piping whose route is judged likely based on visible entry and exit points but was not directly observed along its full accessible length |
| Concealed piping | Piping enclosed by a wall, floor, ceiling, or other finish that cannot be observed without demolition |
| Unresolved piping | Piping whose function, source, or destination cannot be confidently identified using approved non-destructive observation |
| Fixture branch | The supply or drain piping serving one specific fixture or appliance, traced from the fixture back to its identifiable source or connection |
Controlled Area and Mapping Scope Record
Before beginning any tracing, record the defined controlled area and mapping scope directly on the System-Layout Worksheet:
Controlled area: ______ Fixtures included: ______ Appliances included: ______
Available drawings on hand: ______ (Yes/No) Date started: ____________ Builder name: ____________
Prerequisites
- A completed Work-Area Readiness Record from Project 01 for the same controlled area, if the mapped area was drained and protected under that project
- Available plumbing drawings, fixture schedules, inspection records, or owner information for the controlled area, if any exist
- Access to the building water entry, main shutoff, water heater, and the fixtures, valves, and cleanouts within the controlled area
- Basic hand tools and PPE listed in the Tools, Equipment, Materials, Consumables, and PPE tables above
- A stop-work decision authority — the learner, supervisor, or licensed professional who will be notified if an unresolved or conflicting condition affects a dependent project
Common Field Fundamentals
Every plumbing project in this book depends on knowing exactly which piping is supply, which is drain, and which is vent before that piping is touched. Learning to trace and document that distinction here, using only accessible observation, means every later project starts from a system map you already trust.
Entry pointBuilding water entry, meter, main shutoff, and water heater located
Supply IDHot and cold distribution piping identified by material, size, and direction
Branch tracingEach fixture branch traced back to its identifiable source without opening walls
DWV IDDrain, waste, and vent piping identified by material, orientation, and termination
System separationSanitary drainage distinguished from storm, condensate, sump, irrigation, gas, and hydronic piping
Valve and cleanout IDShutoffs, branch valves, appliance valves, and cleanouts located and labeled
Confidence markingEvery observation recorded as verified, inferred, concealed, or unresolved
DocumentationSketch and worksheet completed and compared against any available drawings
Verified, Inferred, Concealed, and Unresolved Piping
Every pipe recorded in this project's sketch and worksheet must carry one of four confidence markings: verified, inferred, concealed, or unresolved. A pipe is verified only when its material, size, direction, and connected fixture have been directly observed. A pipe is inferred when its likely route is judged from visible entry and exit points but was not directly observed along its full accessible length. Concealed piping is piping enclosed by a finish that cannot be observed without demolition. Unresolved piping is piping whose function cannot be confidently identified using approved non-destructive methods.
PL-007 – PL-012
System Identification / Non-Destructive Tracing / Layout Documentation Qualification
Identify Water Supply and Drain Systems
A. Finished-Project Specification
Quantity: one defined controlled area, fully traced for accessible hot and cold supply piping, drain-waste-vent piping, shutoffs, and cleanouts, sketched with distinct supply, drain, and vent symbols, and documented on one completed System-Layout Worksheet identifying verified, inferred, concealed, and unresolved portions.
B. System-Layout Schedule
| Item | Target Condition | Verification Method |
|---|---|---|
| Controlled area | Fixtures, appliances, and visible piping to be mapped defined and do not change mid-project | Written record on worksheet |
| Entry-point identification | Building water entry, meter where accessible, main shutoff, treatment equipment, and water heater located | Direct observation and photograph |
| Supply identification | Hot and cold distribution piping identified by material, size marking, direction, and connected fixture | Direct observation and pipe-marking record |
| Branch tracing | Each selected fixture branch traced to its identifiable source without opening concealed walls | Field sketch cross-checked against direct observation |
| DWV identification | Drain, waste, and vent piping identified by material, fitting orientation, flow direction, cleanouts, traps, and termination | Direct observation and photograph |
| System separation | Sanitary drainage distinguished from storm, condensate, sump, irrigation, gas, hydronic, and other systems | Direct observation and comparison with available drawings |
| Documentation | Sketch and worksheet complete with confidence marking for every recorded pipe | Review against Acceptance Standards |
C. Material Takeoff
- Documentation materials: one System-Layout Worksheet, sketch paper or grid paper sufficient for the controlled area, and a clipboard for field recording.
- Labeling supplies: durable, non-damaging labels for identified shutoffs and cleanouts.
- Photographs: representative images of piping routes, control points, valves, and cleanouts sufficient to support the written record.
D. Acceptance Standards
| Check | Standard |
|---|---|
| Entry-point identification | Building water entry, main shutoff, treatment equipment, and water heater correctly located and recorded |
| Supply identification | Every accessible hot and cold supply run in the controlled area recorded with material, size, direction, and connected fixture |
| Branch tracing | Every selected fixture branch traced to its identifiable source using only non-destructive observation |
| DWV identification | Every accessible drain, waste, and vent run recorded with material, fitting orientation, flow direction, cleanouts, traps, and termination |
| System separation | No sanitary drainage confused with storm, condensate, sump, irrigation, gas, or hydronic piping in the final record |
| Confidence marking | Every recorded pipe marked verified, inferred, concealed, or unresolved; no guessed function assigned to unresolved piping |
| Documentation | Sketch, pipe schedule, and worksheet complete; discrepancies against available drawings noted; proceed or stop-work decision recorded |
E. Preparation and Prior Records Review
- Obtain available plumbing drawings, fixture schedules, inspection records, and owner information. Note any information that identifies pipe routes or flags a prior issue in the controlled area.
- Select the controlled area and define which fixtures, appliances, and visible piping will be mapped. Record this scope in writing before tracing begins.
F. Entry-Point and Supply Identification
- Locate the building water entry, meter where accessible, main shutoff, pressure-control equipment, treatment equipment, and water heater. Photograph each control point.
- Identify visible cold-water distribution piping by material, size marking, direction, and connected fixtures. Record each observation on the worksheet.
- Identify visible hot-water distribution piping from the water heater to served fixtures. Record the route and connected fixtures.
- Locate fixture stops, branch valves, appliance valves, hose connections, and drain-down points. Mark each on the field sketch.
G. Branch Tracing
- Trace each selected fixture supply branch without opening concealed walls or assuming the route through inaccessible spaces. Mark any portion that cannot be directly observed as inferred or concealed rather than assumed verified.
H. DWV Identification and System Separation
- Identify visible drain, waste, and vent piping by material, fitting orientation, direction of flow, cleanouts, traps, and roof or wall vent termination. Record each observation on the worksheet.
- Distinguish sanitary drainage from storm drainage, condensate, sump, irrigation, fuel-gas, hydronic, and other systems. Note the basis for each distinction, such as pipe material, slope direction, or connection point.
- Confirm uncertain piping using non-destructive observations and approved test methods. Do not disturb or tap into piping to confirm its function.
- Mark unidentified or conflicting piping as unresolved rather than assigning a guessed function. Record what prevents confirmation for each unresolved item.
I. Recording, Sketching, and Labeling
- Record accessible pipe markings, nominal sizes, material types, valve types, and fitting transitions. Complete the pipe schedule on the worksheet.
- Sketch the fixture-to-branch relationships using distinct supply, drain, and vent symbols. Use a consistent symbol key across the entire sketch.
- Label shutoffs and cleanouts using durable, non-damaging identification. Confirm each label is legible and correctly placed.
- Note corrosion, unsupported piping, improper transitions, leakage, cross-connection concerns, inaccessible valves, or missing cleanouts. Record each condition with its location.
- Photograph representative piping routes and control points. Confirm photographs correspond to worksheet entries.
J. Comparison and Final Documentation
- Compare the field map with available drawings and note discrepancies. Record each discrepancy and its likely cause.
- Prepare a final system-layout record identifying verified, inferred, concealed, and unresolved portions. Confirm every recorded pipe carries exactly one confidence marking.
- Issue a proceed or stop-work decision for projects that depend on the mapped system. State the decision in writing and identify any unresolved condition that must be corrected or escalated first.
Common Documentation Inspection
Inspect every completed system-layout record using the same checks regardless of which controlled area the project involves.
- Entry-point check: confirm the building water entry, main shutoff, treatment equipment, and water heater are correctly located and recorded.
- Supply check: confirm every accessible hot and cold run is recorded with material, size, direction, and connected fixture.
- Branch-tracing check: confirm every selected fixture branch was traced using only non-destructive observation.
- DWV check: confirm every accessible drain, waste, and vent run is recorded with material, orientation, flow direction, and termination.
- Separation check: confirm sanitary drainage is not confused with storm, condensate, sump, irrigation, gas, or hydronic piping.
- Confidence-marking check: confirm every recorded pipe carries a verified, inferred, concealed, or unresolved marking, with no guessed function assigned.
Complete the System-Layout Worksheet in the Inspection Checklist section below before beginning Project 03.
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Failure Points and Troubleshooting
Cleanup
This project ends with the controlled area returned to its original condition and the system-layout record complete and stored for later reference.
- Return cabinet contents, access panels, and cleanout covers to their original position
- Confirm no tools, labels, or materials were left behind in the controlled area
- Confirm all photographs are labeled and associated with their corresponding worksheet entries
- Leave identified shutoffs and cleanouts labeled for future reference
- Store the System-Layout Worksheet and sketch with the Work-Area Readiness Worksheet from Project 01 for reference by later projects
Field Terms
- Controlled Area
- The bathroom, kitchen, or utility area selected for mapping in this project.
- Verified Piping
- Piping whose material, size, direction, and connected fixture have been directly observed.
- Inferred Piping
- Piping whose route is judged likely from visible entry and exit points but not directly observed along its full accessible length.
- Concealed Piping
- Piping enclosed by a finish that cannot be observed without demolition.
- Unresolved Piping
- Piping whose function cannot be confidently identified using approved non-destructive observation.
- Fixture Branch
- The supply or drain piping serving one specific fixture or appliance, traced from the fixture back to its identifiable source.
- System-Layout Worksheet
- The document recording pipe markings, sizes, materials, valve types, confidence markings, and the proceed or stop-work decision.
- Proceed/Stop-Work Decision
- The documented determination of whether a dependent project may begin based on the completeness and confidence of the system-layout record.
Skill Check
- What four confidence markings must every recorded pipe carry, and how does each differ from the others?
- Why must a fixture supply branch be traced without opening a concealed wall in this project?
- What non-destructive methods may be used to confirm uncertain piping, and what methods are not permitted?
- Why must sanitary drainage be distinguished from storm, condensate, sump, irrigation, gas, and hydronic piping before any later project proceeds?
- What must the learner do when a pipe's function cannot be confidently identified?
- Why must a discrepancy between the field map and an available drawing be recorded rather than resolved by assumption?
- What information must be recorded for every identified shutoff and cleanout?
- Why does a proceed or stop-work decision depend on the confidence markings recorded in the system-layout record?
- What hazard is created by testing or tapping into an unidentified pipe to determine its function?
- Why must the controlled area and mapping scope be defined in writing before tracing begins?
Competency Rubric
| Competency | Independent Pass Standard | Not Demonstrated | With Assistance | Independently |
|---|---|---|---|---|
| PL-007 | Identifies hot and cold water-supply lines by material, size marking, direction, and connected fixture for every accessible run in the controlled area | |||
| PL-008 | Identifies visible DWV piping by material, fitting orientation, and direction of flow for every accessible run in the controlled area | |||
| PL-009 | Traces fixture supply branches from the fixture to the identifiable source using only non-destructive, accessible observation | |||
| PL-010 | Identifies vent piping and distinguishes it from supply and drain piping by location, orientation, and termination | |||
| PL-011 | Identifies and labels shutoffs, cleanouts, and valve types serving the mapped area | |||
| PL-012 | Documents the system layout in a verified, labeled record that correctly distinguishes verified, inferred, concealed, and unresolved piping and states a proceed or stop-work decision |
Mark one column per competency. Only Demonstrated Independently awards the competency; Demonstrated with Assistance authorizes additional supervised practice but does not complete the requirement.
Inspection Checklist — System-Layout Worksheet
| Item | Target Condition | Result | Pass/Fail | Correction (if any) |
|---|---|---|---|---|
| Controlled area | Defined in writing before tracing begins | |||
| Entry-point identification | Water entry, main shutoff, treatment equipment, and water heater located and recorded | |||
| Supply identification | Hot and cold runs recorded with material, size, direction, and connected fixture | |||
| Branch tracing | Every selected branch traced to its identifiable source without opening concealed walls | |||
| DWV identification | Drain, waste, and vent runs recorded with material, orientation, flow direction, and termination | |||
| Confidence marking | Every recorded pipe marked verified, inferred, concealed, or unresolved | |||
| Documentation | Sketch, pipe schedule, and discrepancy notes complete |
Unresolved piping and escalation plan: ____________________________________________
Proceed / stop-work decision: ______ (Proceed/Stop-Work) Date: ____________ Builder name: ____________
Performance Check
With the entry point located, supply and DWV piping identified, fixture branches traced, and the sketch and worksheet complete, review the finished system-layout record against the Acceptance Standards table and confirm every accessible supply and DWV run is correctly identified, every traced branch was confirmed using only non-destructive observation, sanitary drainage is not confused with any other piping system, every recorded pipe carries a correct confidence marking, and a proceed or stop-work decision has been recorded for any project that depends on the mapped system. Complete the System-Layout Worksheet and correct any failed item before beginning Project 03. If an item fails, identify whether the error occurred in identification, tracing, system separation, or documentation before correcting it and re-running the affected check.
Project Closeout
You have completed the second project in the residential plumbing sequence: identifying residential water supply and drain systems. This project required you to identify hot and cold supply lines, identify DWV piping, trace fixture branches, identify vents, identify shutoffs, and document the system layout (PL-007 through PL-012).
You now have a verified system-layout record for the controlled area, plus a repeatable tracing and documentation method you can reuse for any area in this book. That record carries directly into the next project: measuring, cutting, and preparing copper, PEX, and PVC pipe for the joining systems taught in Chapters 4 through 8.
Keep your System-Layout Worksheet and sketch with your Project 01 records. You will reference this system map before every pipe, fixture, and appliance project in the rest of this book.