MasterPlumberPractice
Chapter V

System Testing

MasterPlumberPractice study guide with diagrams.

Study Chapter: System Testing

Georgia Master Plumber License Exam (GA-MST)

Learning Objectives

By the end of this chapter, you will be able to:

6.Identify the mandatory testing requirements for DWV, water supply, and gas piping systems under the 2018 Georgia Plumbing Code and 2018 Georgia Gas Code.
7.Distinguish between the methods, durations, and pressure thresholds for water, air, and gas tests.
8.Apply the code’s exceptions and sequencing rules (e.g., testing before concealment, rough-in vs. final tests).
9.Recognize the licensed master plumber’s legal responsibility for test performance, documentation, and safety during testing.
10.Navigate the code structure to locate specific testing sections quickly.

1.1 The Regulatory Framework and Master Plumber Responsibility

System testing is not merely a procedural step; it is a code-mandated verification of workmanship and a safety barrier against property damage and health hazards. Under the 2018 Georgia Plumbing Code (based on the 2018 IPC with state amendments) and the 2018 Georgia Gas Code (based on the 2018 IFGC with state amendments), the permit holder—typically the master plumber of record—is responsible for ensuring that all required tests are performed, witnessed by the authority having jurisdiction (AHJ) when required, and that the system is left in a safe condition.

For the closed-book GA-MST exam, you must know when to test, how to test, what pressure to use, and who is accountable. The code does not allow a journeyman to act independently in certifying tests; the master is the responsible licensed individual.

1.2 Testing of Drainage, Waste, and Vent (DWV) Systems

1.2.1 General Requirements and Timing

The primary testing provisions for DWV systems are found in Chapter 3 of the IPC (General Regulations), specifically in the section addressing system testing. The Georgia amendments do not relax these requirements; they may add stricter local conditions, but the baseline is the IPC.

Key timing rule: All DWV piping must be tested before covering or concealing. This includes rough-in testing before the installation of fixtures and final testing after fixtures are set. The test must be applied to the complete system or in sections, at the discretion of the plumber, but the AHJ must be given reasonable notice to witness the test.

1.2.2 Water Test Method

DWV Water Test Setup and Head Requirement — GA MST Chapter 5 DWV Water Test Setup and Head Requirement GA MST Chapter 5 — System Testing · IPC/IFGC 2018 Amendments · Closed-Book Reference TEST TEE FILL HOSE 10 FT HEAD ≈ 4.3 psi 15 MIN HOLD TIME 4.3 PSI STATIC HEAD TALL BUILDINGS Test in vertical sections so static head never exceeds pipe pressure rating. TO BUILDING DRAIN TEST PLUG TEST REQUIREMENTS 10-foot head of water (min) Hold 15 minutes without leakage Test entire DWV system Open fixtures — water seeks its own level If leaks: locate & repair, then retest PRESSURE RATING CHECK Static head = 0.433 psi per ft 10 ft × 0.433 = 4.33 psi ⚠ Exceed pipe rating → section the test SECTION TESTING SEC. A SEC. B MasterPlumberPractice Water column Test tee w/ plug Bottom test plug DWV piping GA MST §305.1 · IPC 2018 §312.2

The most common method is the water test. The system is filled with water to the highest point of the vent stack (or a test tee at the top of the system). The code requires a 10-foot head of water (approximately 4.3 psi) to be maintained for a period of 15 minutes without leakage. The pressure is measured from the highest point of the system under test.

Important detail: If the building is tall and the static head of water exceeds the pressure rating of the piping material (e.g., cast iron or PVC), the test must be performed in vertical sections to avoid over-pressurizing lower joints. The code does not require you to test the entire stack at once if doing so would exceed the manufacturer’s pressure rating.

1.2.3 Air Test Method

An air test is permitted as an alternative. The system is pressurized to 5 psi (pounds per square inch) and must hold that pressure for 15 minutes without a drop. The code allows a slight tolerance for temperature changes, but any measurable drop indicates a leak.

Critical safety point: The air test must be performed with a pressure gauge and a relief valve set at 5 psi. Over-pressurization of DWV piping can cause explosive failure. The master plumber is responsible for ensuring that all test plugs are secured and that no one is near a joint when pressure is applied.

1.2.4 Final Test After Fixtures

After all fixtures are installed and connected, a final test is required. This is typically a water test applied to the entire system, including the fixture traps, to ensure that no leaks exist at the fixture connections. The water test is run through the vent system, and each trap is checked for seal retention.

Exam trap: Some candidates confuse the final test with the rough-in test. The final test is not a simple visual check; it is a full pressure test. However, the code does allow the final test to be a smoke test in some jurisdictions, but Georgia’s adoption generally follows the IPC, which permits water or air only.

1.3 Testing of Water Supply Systems

1.3.1 Rough-In and Final Testing

Water supply piping must be tested after rough-in and before concealment, and again after fixtures are connected. The test is found in Chapter 6 of the IPC (Water Supply and Distribution).

1.3.2 Pressure and Duration

Water Supply Pressure Test at 80 psi Minimum — GA MST Chapter 5 System Testing Water Supply Pressure Test — 80 psi Minimum GA MST Ch.5 System Testing · IPC/IFGC 2018 amendments · Master Plumber 80 psi MINIMUM ▼ Code Rule — Test Pressure Test at not less than 80 psi OR the maximum working pressure, whichever is greater. ▲ If Building Supply Exceeds 80 psi… 0 psi 40 psi 80 psi 120+ psi 80 psi System working pressure = 110 psi Test pressure must be raised to 110 psi, not 80 psi ⏱ Hold Time — 15 Minutes 15 minutes Hold pressure for 15 minutes with zero drop in pressure ✓ 0 psi drop = PASS 💧 Test Medium Water — not air — is the required Pressure after 15 min: 80 psi (unchanged) Result: ✓ PASS MasterPlumberPractice V T Water is the required test medium (air test not permitted for water piping) 📋 Code Reference IPC 2018 §312.2 · GA Amendment: 80 psi minimum, 15-min hold Test pressure = greater of (80 psi, max working pressure) · Zero drop required

The water supply system must be tested at not less than 80 psi (or the maximum working pressure of the system, whichever is greater) for a duration of 15 minutes. The test is performed using water, not air, unless the AHJ approves an air test. The system must hold the pressure without any drop.

Important nuance: If the building’s water pressure exceeds 80 psi, the test pressure must be raised to the system’s maximum working pressure. The code does not cap the test at 80 psi; it sets a minimum.

1.3.3 Testing Before Connection to the Main

The water service line from the public main to the building must be tested before connection to the main, typically by the utility or the plumber under permit. The test is usually a hydrostatic test at 80 psi or 1.5 times the working pressure, whichever is greater, for 15 minutes.

Field point: The master plumber must coordinate with the water utility to ensure the test is witnessed and documented before backfilling the trench. Failure to do so may require excavation and retesting.

1.3.4 Air Testing of Water Lines

While water is the preferred medium, an air test may be used for temporary testing of water lines before they are connected to fixtures. The air test pressure is typically 50 psi for 15 minutes. However, this is riskier and must be done with extreme caution. The code requires that all air be bled from the system before the water test is performed.

1.4 Testing of Gas Piping Systems (2018 Georgia Gas Code)

1.4.1 Applicability and Standards

Gas piping testing is governed by the 2018 Georgia Gas Code (IFGC with amendments), specifically Chapter 4 (Gas Piping Installations). The master plumber who installs gas piping is responsible for testing per NFPA 54/ANSI Z223.1 (National Fuel Gas Code), which is referenced by the IFGC.

1.4.2 Test Pressure and Duration

Gas Piping Test Pressure and Duration - GA MST Chapter 5 Gas Piping Test Pressure and Duration GA-MST Chapter 5 — System Testing · IPC/IFGC 2018 Amendments · Master Plumber Theory AIR / NITROGEN PSI TEST GAUGE Not less than 10 psi TEST BLACK STEEL APPLIANCE PRESSURE REQUIREMENT • Not less than 10 psi OR 1.5× max working pressure • Use 15 psi for combination systems (typical) ✓ ACCEPTABLE • Air • Nitrogen • Inert gas (Non-flammable, non-corrosive) ✗ PROHIBITED • Oxygen • Fuel gas Oxygen + fuel = explosion hazard risk 30 MIN DURATION — SYSTEM VOLUME Test duration based on gas piping system volume SYSTEM VOLUME (ft³) TEST DURATION ≤ 10 ft³ 30 minutes > 10 ft³ to ≤ 25 ft³ 60 minutes > 25 ft³ to ≤ 100 ft³ 90 minutes > 100 ft³ 120 minutes VOLUME CALCULATION Sum of pipe volume + fitting allowance 1/2" pipe ≈ 0.016 ft³/ft · 3/4" ≈ 0.036 ft³/ft 1" ≈ 0.064 ft³/ft · 1-1/4" ≈ 0.104 ft³/ft ⏱ TIMING RULE Test begins after pressure stabilizes & all connections checked GA AMENDMENT — 10 PSI MINIMUM IFGC 2018 §406.4.1: 10 psi or 1.5× working pressure, whichever is greater ⚠ GAUGES & RECORDS Gauge must be rated for test pressure and calibrated within 1 year MasterPlumberPractice

The gas piping system must be tested at a pressure of not less than 10 psi (for systems with a test pressure requirement) or 1.5 times the maximum working pressure, whichever is greater. The test is conducted with air, nitrogen, or an inert gas—never with oxygen or fuel gas.

The duration of the test is not fixed at 15 minutes like plumbing; it is 30 minutes for systems with a volume of 10 cubic feet or less, and longer for larger systems (the code provides a table based on cubic footage). For the exam, remember the minimum 10 psi and the 30-minute minimum for typical residential and small commercial systems.

1.4.3 Testing Before Concealment

Gas piping must be tested before being covered or concealed. This includes piping in walls, floors, or underground. The test is performed with all outlets capped or plugged, and the system is brought up to test pressure. A mercury manometer or a digital gauge with appropriate resolution is required to detect small leaks.

1.4.4 Appliance Connection Testing

After appliances are connected, the piping must be retested at the normal operating pressure (typically 7 to 14 inches water column) using a soap-and-water solution or an electronic leak detector. This is a bubble test, not a pressure test. The master plumber must verify that all connections are tight before leaving the job.

Exam trap: Do not confuse the 10 psi rough-in test with the low-pressure final test. The final test is a leak check, not a pressure test.

1.5 Special Testing Situations and Exceptions

1.5.1 Testing of Storm Drainage Systems

Storm drainage piping is tested similarly to sanitary DWV, using a water test with a 10-foot head for 15 minutes. However, the code allows a lesser test for systems that are not connected to a public sewer, at the AHJ’s discretion.

1.5.2 Testing of Roof Drains and Leaders

Roof drains and their vertical leaders must be tested before connection to the storm drainage system. This is often done by filling the leader with water and checking for leaks at the joints.

1.5.3 Testing of Backflow Prevention Assemblies

Backflow prevention devices (e.g., reduced pressure zone assemblies) must be tested upon installation and annually thereafter by a certified tester. The master plumber is responsible for ensuring the initial test is performed and the results are submitted to the AHJ. This is not a pressure test of the piping but a functional test of the device.

1.5.4 When Testing is Not Required

The code does not require testing of exposed piping that is not part of the pressure system (e.g., a condensate drain that is open to the atmosphere). However, any piping that carries water under pressure or waste must be tested.

1.6 Code Navigation: Where to Find Testing Requirements

For the closed-book exam, you must know the chapter and section logic even if you cannot recall the exact section number. Use this map:

ConceptCode Location (Chapter/Section Logic)
DWV water/air testIPC Chapter 3 (General Regulations), section on "System Testing" (around 312)
Water supply testIPC Chapter 6 (Water Supply), section on "Tests" (around 608)
Gas piping testIFGC Chapter 4 (Gas Piping), section on "Inspection and Testing" (around 406)
Test pressure tablesIFGC Table for test duration based on pipe volume
Backflow testingIPC Chapter 6, section on "Backflow Prevention"
Final test after fixturesIPC Chapter 3, same "System Testing" section
Concealment before testIPC Chapter 3, "Concealment" or "Inspection" section

Memory aid: The IPC places all testing in the general regulations (Chapter 3) for DWV, and in the specific system chapter (6) for water. The IFGC places gas testing in Chapter 4.

1.7 Practical Field Points for the Master Plumber

73.Schedule tests with the AHJ early. The inspector must witness the test. Do not cover piping before the test is signed off.
74.Use calibrated gauges. A faulty gauge can cause a false failure or a dangerous over-pressurization. Keep a spare gauge on the truck.
75.Protect the system during the test. For air tests, use a relief valve. For water tests, ensure the system is filled slowly to avoid water hammer.
76.Document everything. Take photos, record gauge readings, and note the time. This protects you in a dispute.
77.Never test with fuel gas or oxygen. Use air, nitrogen, or water. Oxygen and fuel gas create an explosion hazard.
78.Check for cross-connections. Before testing, ensure that no fixture is connected that would allow test water to enter the potable supply.

1.8 Common Exam Traps

Trap: Confusing the 15-minute DWV test with the 30-minute gas test. DWV is 15 minutes; gas is 30 minutes (minimum).
Trap: Using 80 psi for DWV. DWV is tested at a 10-foot head (≈4.3 psi) or 5 psi air. 80 psi is for water supply.
Trap: Testing gas at 10 psi for 15 minutes. The duration is 30 minutes, not 15.
Trap: Believing the final gas test is a pressure test. It is a leak check at operating pressure with soap bubbles.
Trap: Forgetting that the master plumber, not the journeyman, is responsible for the test. The code holds the permit holder accountable.
Trap: Testing water supply with air at 80 psi. Air testing of water lines is allowed only at lower pressures (50 psi) and with caution; 80 psi air is dangerous.
Trap: Assuming the test is done once. Rough-in and final tests are both required for DWV and water supply.

1.9 Summary of Key Numbers

SystemTest MediumPressureDuration
DWV (water test)Water10-ft head (≈4.3 psi)15 min
DWV (air test)Air5 psi15 min
Water supply (hydrostatic)Water≥80 psi15 min
Water supply (air test)Air50 psi15 min
Gas piping (rough-in)Air/N₂≥10 psi30 min (min)
Gas piping (final)Air/N₂Operating pressureSoap bubble check

1.10 Conclusion

System testing is the final barrier between a code-compliant installation and a hidden failure. As a master plumber, you are not only performing a technical task—you are certifying that the work meets the safety standards of the 2018 Georgia Plumbing Code and Gas Code. Master the numbers, understand the sequencing, and always prioritize safety. On the exam, read each question carefully to identify which system is being tested, then apply the correct pressure and duration.

End of Chapter

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