Water Supply and Backflow Practice Questions
Air gaps, vacuum breakers, RP and double check assemblies, cross connections, pressure-reducing valves, water hammer, service and valves, disinfection and pipe sizing.
100 questions in 2 hours, scored against the 70% pass mark, with a score for water supply so you know where you stand.
Free water supply drillNonpotable water piping, such as reclaimed or gray water, must be identified with which color?
Water Supply and Distribution on the journeyman plumber exam
The water supply chapter covers protecting potable water and distributing it. TSBPE lists cross-connection control, approved materials and joining methods; ICC’s Water Supply and Distribution area is 14% of the G25 exam.
- On our mocks
- Texas: 12 of 100 on our Texas mock · ICC G25: 10 of 70 on our ICC G25 mock
- Our drill
- 10 questions from 39 water supply questions, untimed, an explanation and code reference after every answer; one free attempt, unlimited with a pass
What water supply questions test
- Backflow: air gaps (twice the opening, at least 1 inch), atmospheric and pressure vacuum breakers, double check and RP assemblies, and which hazard each covers
- Cross connections at hose bibbs, hand showers, irrigation, boilers and beverage dispensers, and testing of assemblies
- Pressure: reducing valves above 80 psi, water hammer arrestors, head pressure and friction loss
- Service and valves: minimum 3/4-inch service, full-open valves, separation from the sewer
- Disinfection (50 ppm for 24 hours or 200 ppm for 3 hours) and purple nonpotable piping
Sit the full exam under the real clock
100 questions in 2 hours, scored against the 70% pass mark, with a score for water supply so you know where you stand.
Free water supply drillHow to study it
- Sort the backflow devices into a grid: hazard level, backsiphonage, backpressure, continuous pressure.
- Learn the heights: atmospheric vacuum breaker 6 inches and pressure vacuum breaker 12 inches above the highest outlet.
- Work head-pressure questions with 2.31 feet per psi.
Common questions
When is a pressure-reducing valve required?
When the static water pressure exceeds 80 psi, in both the IPC and the UPC.
Which backflow preventer protects a high hazard under continuous pressure?
A reduced pressure principle (RP) assembly, or an air gap. Vacuum breakers do not protect against backpressure.
100 questions in 2 hours, scored against the 70% pass mark, with a score for water supply so you know where you stand.
Free water supply drillThe other sections
- Code Definitions and Plan Reading
- General Regulations, Testing and Plumbing Math
- Pipe Materials and Joints
- Plumbing Fixtures
- Water Heaters
- Sanitary Drainage
- Vents
- Traps, Interceptors and Separators
- Storm Drainage
- Fuel Gas Piping
- Texas Plumbing License Law and Board Rules
- Texas practice exam (100 questions, 2 hours)
- ICC G25 practice exam (70 questions, 4 hours)
- Free Texas mixed drill
Sources
- Pearson VUE: Texas State Board of Plumbing Examiners (retake waits, practical, five attempts)
- TSBPE Candidate Handbook, August 2025 (exam table, fees, 70% passing score, test-center rules)
- TSBPE Journeyman Plumber Examination Review Course, rev 09/2025 (format, codes, chapters, sample questions)
- TSBPE Administrative Rules, March 2026 (22 TAC §§363.5, 363.22, 365.1, 367.2)
- TSBPE proposed amendment to §367.2 (2021 IPC and UPC), Texas Register, August 14, 2026
- TSBPE Strategic Plan 2025-2029 (examination statistics, p. 14)
- ICC National Contractor/Trades Examination Information Bulletin, published June 30, 2026 (G25 Journeyman Plumber)
- ICC Support: What is a passing score?
Original practice questions written to the TSBPE Journeyman Plumber Examination Review Course, ICC’s G25 content outline and the 2018 International Plumbing Code and Uniform Plumbing Code; they are not exam questions and quote no code text. Independent practice, not affiliated with or endorsed by the Texas State Board of Plumbing Examiners, the International Code Council, IAPMO or Pearson VUE.